hugetlbfs: improve read HWPOISON hugepage

When a hugepage contains HWPOISON pages, read() fails to read any byte of
the hugepage and returns -EIO, although many bytes in the HWPOISON
hugepage are readable.

Improve this by allowing hugetlbfs_read_iter returns as many bytes as
possible.  For a requested range [offset, offset + len) that contains
HWPOISON page, return [offset, first HWPOISON page addr); the next read
attempt will fail and return -EIO.

Link: https://lkml.kernel.org/r/20230713001833.3778937-4-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hwpoison: check if a raw page in a hugetlb folio is raw HWPOISON

Add the functionality, is_raw_hwpoison_page_in_hugepage, to tell if a raw
page in a hugetlb folio is HWPOISON.  This functionality relies on
RawHwpUnreliable to be not set; otherwise hugepage's raw HWPOISON list
becomes meaningless.

is_raw_hwpoison_page_in_hugepage holds mf_mutex in order to synchronize
with folio_set_hugetlb_hwpoison and folio_free_raw_hwp who iterate,
insert, or delete entry in raw_hwp_list.  llist itself doesn't ensure
insertion and removal are synchornized with the llist_for_each_entry used
by is_raw_hwpoison_page_in_hugepage (unless iterated entries are already
deleted from the list).  Caller can minimize the overhead of lock cycles
by first checking HWPOISON flag of the folio.

Exports this functionality to be immediately used in the read operation
for hugetlbfs.

Link: https://lkml.kernel.org/r/20230713001833.3778937-3-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hwpoison: delete all entries before traversal in __folio_free_raw_hwp

Patch series "Improve hugetlbfs read on HWPOISON hugepages", v4.

Today when hardware memory is corrupted in a hugetlb hugepage, kernel
leaves the hugepage in pagecache [1]; otherwise future mmap or read will
suject to silent data corruption.  This is implemented by returning -EIO
from hugetlb_read_iter immediately if the hugepage has HWPOISON flag set.

Since memory_failure already tracks the raw HWPOISON subpages in a
hugepage, a natural improvement is possible: if userspace only asks for
healthy subpages in the pagecache, kernel can return these data.

This patchset implements this improvement.  It consist of three parts.
The 1st commit exports the functionality to tell if a subpage inside a
hugetlb hugepage is a raw HWPOISON page.  The 2nd commit teaches
hugetlbfs_read_iter to return as many healthy bytes as possible.  The 3rd
commit properly tests this new feature.

[1] commit 8625147cafaa ("hugetlbfs: don't delete error page from pagecache")

This patch (of 4):

Traversal on llist (e.g.  llist_for_each_safe) is only safe AFTER entries
are deleted from the llist.  Correct the way __folio_free_raw_hwp deletes
and frees raw_hwp_page entries in raw_hwp_list: first llist_del_all, then
kfree within llist_for_each_safe.

As of today, concurrent adding, deleting, and traversal on raw_hwp_list
from hugetlb.c and/or memory-failure.c are fine with each other.  Note
this is guaranteed partly by the lock-free nature of llist, and partly by
holding hugetlb_lock and/or mf_mutex.  For example, as llist_del_all is
lock-free with itself, folio_clear_hugetlb_hwpoison()s from
__update_and_free_hugetlb_folio and memory_failure won't need explicit
locking when freeing the raw_hwp_list.  New code that manipulates
raw_hwp_list must be careful to ensure the concurrency correctness.

Link: https://lkml.kernel.org/r/20230713001833.3778937-1-jiaqiyan@google.com
Link: https://lkml.kernel.org/r/20230713001833.3778937-2-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan <jiaqiyan@google.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mmap: move vma operations to mm_struct out of the critical section of file mapping lock

UnixBench/Execl represents a class of workload where bash scripts are
spawned frequently to do some short jobs.  When running multiple parallel
tasks, hot osq_lock is observed from do_mmap and exit_mmap.  Both of them
come from load_elf_binary through the call chain
"execl->do_execveat_common->bprm_execve->load_elf_binary".

In do_mmap,it will call mmap_region to create vma node, initialize it and
insert it to vma maintain structure in mm_struct and i_mmap tree of the
mapping file, then increase map_count to record the number of vma nodes
used.  The hot osq_lock is to protect operations on file's i_mmap tree.
For the mm_struct member change like vma insertion and map_count update,
they do not affect i_mmap tree.  Move those operations out of the lock's
critical section, to reduce hold time on the lock.

With this change, on Intel Sapphire Rapids 112C/224T platform, based on
v6.0-rc6, the 160 parallel score improves by 12%.  The patch has no
obvious performance gain on v6.5-rc1 due to regression of this benchmark
from this commit f1a7941243c102a44e8847e3b94ff4ff3ec56f25 (mm: convert
mm's rss stats into percpu_counter).  Related discussion and conclusion
can be referred at the mail thread initiated by 0day as below: Link:
https://lore.kernel.org/linux-mm/a4aa2e13-7187-600b-c628-7e8fb108def0@intel.com/

Link: https://lkml.kernel.org/r/20230712145739.604215-1-yu.ma@intel.com
Signed-off-by: Yu Ma <yu.ma@intel.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zhu, Lipeng <lipeng.zhu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove clear_page_idle()

All callers have now been converted to call folio_clear_idle().

Link: https://lkml.kernel.org/r/20230712134959.145373-1-xueshi.hu@smartx.com
Signed-off-by: Xueshi Hu <xueshi.hu@smartx.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/pgtable: notes on pte_offset_map[_lock]()

Add a block of comments on pte_offset_map_lock(), pte_offset_map() and
pte_offset_map_nolock() to mm/pgtable-generic.c, to help explain them.

Link: https://lkml.kernel.org/r/b791c3b0-25c6-a263-d785-d564344eb644@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: delete mmap_write_trylock() and vma_try_start_write()

mmap_write_trylock() and vma_try_start_write() were added just for
khugepaged, but now it has no use for them: delete.

Link: https://lkml.kernel.org/r/4e6db3d-e8e-73fb-1f2a-8de2dab2a87c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: delete khugepaged_collapse_pte_mapped_thps()

Now that retract_page_tables() can retract page tables reliably, without
depending on trylocks, delete all the apparatus for khugepaged to try
again later: khugepaged_collapse_pte_mapped_thps() etc; and free up the
per-mm memory which was set aside for that in the khugepaged_mm_slot.

But one part of that is worth keeping: when hpage_collapse_scan_file()
found SCAN_PTE_MAPPED_HUGEPAGE, that address was noted in the mm_slot to
be tried for retraction later - catching, for example, page tables where a
reversible mprotect() of a portion had required splitting the pmd, but now
it can be recollapsed.  Call collapse_pte_mapped_thp() directly in this
case (why was it deferred before?  I assume an issue with needing
mmap_lock for write, but now it's only needed for read).

[hughd@google.com: fix mmap_locked handlng]
Link: https://lkml.kernel.org/r/bfc6cab2-497f-32bf-dd5-98dc1987e4a9@google.com
Link: https://lkml.kernel.org/r/a5dce57-6dfa-5559-4698-e817eb2f993@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: collapse_pte_mapped_thp() with mmap_read_lock()

Bring collapse_and_free_pmd() back into collapse_pte_mapped_thp().  It
does need mmap_read_lock(), but it does not need mmap_write_lock(), nor
vma_start_write() nor i_mmap lock nor anon_vma lock.  All racing paths are
relying on pte_offset_map_lock() and pmd_lock(), so use those.

Follow the pattern in retract_page_tables(); and using pte_free_defer()
removes most of the need for tlb_remove_table_sync_one() here; but call
pmdp_get_lockless_sync() to use it in the PAE case.

First check the VMA, in case page tables are being torn down: from JannH.
Confirm the preliminary find_pmd_or_thp_or_none() once page lock has been
acquired and the page looks suitable: from then on its state is stable.

However, collapse_pte_mapped_thp() was doing something others don't:
freeing a page table still containing "valid" entries.  i_mmap lock did
stop a racing truncate from double-freeing those pages, but we prefer
collapse_pte_mapped_thp() to clear the entries as usual.  Their TLB flush
can wait until the pmdp_collapse_flush() which follows, but the
mmu_notifier_invalidate_range_start() has to be done earlier.

Do the "step 1" checking loop without mmu_notifier: it wouldn't be good
for khugepaged to keep on repeatedly invalidating a range which is then
found unsuitable e.g.  contains COWs.  "step 2", which does the clearing,
must then be more careful (after dropping ptl to do mmu_notifier), with
abort prepared to correct the accounting like "step 3".  But with those
entries now cleared, "step 4" (after dropping ptl to do pmd_lock) is kept
safe by the huge page lock, which stops new PTEs from being faulted in.

[hughd@google.com: don't set mmap_locked = true in madvise_collapse()]
Link: https://lkml.kernel.org/r/d3d9ff14-ef8-8f84-e160-bfa1f5794275@google.com
[hughd@google.com: use ptep_clear() instead of pte_clear()]
Link: https://lkml.kernel.org/r/e0197433-8a47-6a65-534d-eda26eeb78b0@google.com
Link: https://lkml.kernel.org/r/b53be6a4-7715-51f9-aad-f1347dcb7c4@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: retract_page_tables() without mmap or vma lock

Simplify shmem and file THP collapse's retract_page_tables(), and relax
its locking: to improve its success rate and to lessen impact on others.

Instead of its MADV_COLLAPSE case doing set_huge_pmd() at target_addr of
target_mm, leave that part of the work to madvise_collapse() calling
collapse_pte_mapped_thp() afterwards: just adjust collapse_file()'s result
code to arrange for that.  That spares retract_page_tables() four
arguments; and since it will be successful in retracting all of the page
tables expected of it, no need to track and return a result code itself.

It needs i_mmap_lock_read(mapping) for traversing the vma interval tree,
but it does not need i_mmap_lock_write() for that: page_vma_mapped_walk()
allows for pte_offset_map_lock() etc to fail, and uses pmd_lock() for
THPs.  retract_page_tables() just needs to use those same spinlocks to
exclude it briefly, while transitioning pmd from page table to none: so
restore its use of pmd_lock() inside of which pte lock is nested.

Users of pte_offset_map_lock() etc all now allow for them to fail: so
retract_page_tables() now has no use for mmap_write_trylock() or
vma_try_start_write().  In common with rmap and page_vma_mapped_walk(), it
does not even need the mmap_read_lock().

But those users do expect the page table to remain a good page table,
until they unlock and rcu_read_unlock(): so the page table cannot be freed
immediately, but rather by the recently added pte_free_defer().

Use the (usually a no-op) pmdp_get_lockless_sync() to send an interrupt
when PAE, and pmdp_collapse_flush() did not already do so: to make sure
that the start,pmdp_get_lockless(),end sequence in __pte_offset_map()
cannot pick up a pmd entry with mismatched pmd_low and pmd_high.

retract_page_tables() can be enhanced to replace_page_tables(), which
inserts the final huge pmd without mmap lock: going through an invalid
state instead of pmd_none() followed by fault.  But that enhancement does
raise some more questions: leave it until a later release.

Link: https://lkml.kernel.org/r/f88970d9-d347-9762-ae6d-da978e8a4df@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/pgtable: add pte_free_defer() for pgtable as page

Add the generic pte_free_defer(), to call pte_free() via call_rcu().
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon.  This version
suits all those architectures which use an unfragmented page for one page
table (none of whose pte_free()s use the mm arg which was passed to it).

Link: https://lkml.kernel.org/r/78e921b0-b681-a1b0-dc20-44c9efa4ef3c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

s390: add pte_free_defer() for pgtables sharing page

Add s390-specific pte_free_defer(), to free table page via call_rcu().
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon.  This precedes
the generic version to avoid build breakage from incompatible pgtable_t.

This version is more complicated than others: because s390 fits two 2K
page tables into one 4K page (so page->rcu_head must be shared between
both halves), and already uses page->lru (which page->rcu_head overlays)
to list any free halves; with clever management by page->_refcount bits.

Build upon the existing management, adjusted to follow a new rule: that a
page is never on the free list if pte_free_defer() was used on either half
(marked by PageActive).  And for simplicity, delay calling RCU until both
halves are freed.

Not adding back unallocated fragments to the list in pte_free_defer() can
result in wasting some amount of memory for pagetables, depending on how
long the allocated fragment will stay in use.  In practice, this effect is
expected to be insignificant, and not justify a far more complex approach,
which might allow to add the fragments back later in __tlb_remove_table(),
where we might not have a stable mm any more.

[hughd@google.com: Claudio finds warning on mm_has_pgste() more useful than on mm_alloc_pgste()]
Link: https://lkml.kernel.org/r/3bc095ba-a180-ce3b-82b1-2bfc64612f3@google.com
Link: https://lkml.kernel.org/r/94eccf5f-264c-8abe-4567-e77f4b4e14a@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Tested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

sparc: add pte_free_defer() for pte_t *pgtable_t

Add sparc-specific pte_free_defer(), to call pte_free() via call_rcu().
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon.  This precedes
the generic version to avoid build breakage from incompatible pgtable_t.

sparc32 supports pagetables sharing a page, but does not support THP;
sparc64 supports THP, but does not support pagetables sharing a page.  So
the sparc-specific pte_free_defer() is as simple as the generic one,
except for converting between pte_t *pgtable_t and struct page *.

Link: https://lkml.kernel.org/r/dc4f318d-a66a-5622-dc44-9018ea814b37@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

powerpc: add pte_free_defer() for pgtables sharing page

Add powerpc-specific pte_free_defer(), to free table page via call_rcu().
pte_free_defer() will be called inside khugepaged's retract_page_tables()
loop, where allocating extra memory cannot be relied upon.  This precedes
the generic version to avoid build breakage from incompatible pgtable_t.

This is awkward because the struct page contains only one rcu_head, but
that page may be shared between PTE_FRAG_NR pagetables, each wanting to
use the rcu_head at the same time.  But powerpc never reuses a fragment
once it has been freed: so mark the page Active in pte_free_defer(),
before calling pte_fragment_free() directly; and there call_rcu() to
pte_free_now() when last fragment is freed and the page is PageActive.

Link: https://lkml.kernel.org/r/6e3ca5f1-334d-4b14-b92d-fc8e99914fcb@google.com
Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

powerpc: assert_pte_locked() use pte_offset_map_nolock()

Instead of pte_lockptr(), use the recently added pte_offset_map_nolock()
in assert_pte_locked().  BUG if pte_offset_map_nolock() fails.

This mod might cause new crashes: which either expose my ignorance, or
indicate issues to be fixed, or limit the usage of assert_pte_locked().

[hughd@google.com: assert_pte_locked() still needs the pmd_none() check]
Link: https://lkml.kernel.org/r/c73d1543-532c-3da2-8cf2-a95363a14116@google.com
Link: https://lkml.kernel.org/r/e8d56c95-c132-a82e-5f5f-7bb1b738b057@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arm: adjust_pte() use pte_offset_map_nolock()

Instead of pte_lockptr(), use the recently added pte_offset_map_nolock()
in adjust_pte(): because it gives the not-locked ptl for precisely that
pte, which the caller can then safely lock; whereas pte_lockptr() is not
so tightly coupled, because it dereferences the pmd pointer again.

Link: https://lkml.kernel.org/r/4d5258bd-ffa0-018-253a-25f2c9b783f7@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/pgtable: add PAE safety to __pte_offset_map()

There is a faint risk that __pte_offset_map(), on a 32-bit architecture
with a 64-bit pmd_t e.g.  x86-32 with CONFIG_X86_PAE=y, would succeed on a
pmdval assembled from a pmd_low and a pmd_high which never belonged
together: their combination not pointing to a page table at all, perhaps
not even a valid pfn.  pmdp_get_lockless() is not enough to prevent that.

Guard against that (on such configs) by local_irq_save() blocking TLB
flush between present updates, as linux/pgtable.h suggests.  It's only
needed around the pmdp_get_lockless() in __pte_offset_map(): a race when
__pte_offset_map_lock() repeats the pmdp_get_lockless() after getting the
lock, would just send it back to __pte_offset_map() again.

Complement this pmdp_get_lockless_start() and pmdp_get_lockless_end(),
used only locally in __pte_offset_map(), with a pmdp_get_lockless_sync()
synonym for tlb_remove_table_sync_one(): to send the necessary interrupt
at the right moment on those configs which do not already send it.

CONFIG_GUP_GET_PXX_LOW_HIGH is enabled when required by mips, sh and x86.
It is not enabled by arm-32 CONFIG_ARM_LPAE: my understanding is that Will
Deacon's 2020 enhancements to READ_ONCE() are sufficient for arm.  It is
not enabled by arc, but its pmd_t is 32-bit even when pte_t 64-bit.

Limit the IRQ disablement to CONFIG_HIGHPTE?  Perhaps, but would need a
little more work, to retry if pmd_low good for page table, but pmd_high
non-zero from THP (and that might be making x86-specific assumptions).

Link: https://lkml.kernel.org/r/3adcd8f-9191-2df1-d7ea-c4877698aad@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s

Patch series "mm: free retracted page table by RCU", v3.

Some mmap_lock avoidance i.e.  latency reduction.  Initially just for the
case of collapsing shmem or file pages to THPs: the usefulness of
MADV_COLLAPSE on shmem is being limited by that mmap_write_lock it
currently requires.

Likely to be relied upon later in other contexts e.g.  freeing of empty
page tables (but that's not work I'm doing).  mmap_write_lock avoidance
when collapsing to anon THPs?  Perhaps, but again that's not work I've
done: a quick attempt was not as easy as the shmem/file case.

These changes (though of course not these exact patches) have been in
Google's data centre kernel for three years now: we do rely upon them.

This patch (of 13):

Before putting them to use (several commits later), add rcu_read_lock() to
pte_offset_map(), and rcu_read_unlock() to pte_unmap().  Make this a
separate commit, since it risks exposing imbalances: prior commits have
fixed all the known imbalances, but we may find some have been missed.

Link: https://lkml.kernel.org/r/7cd843a9-aa80-14f-5eb2-33427363c20@google.com
Link: https://lkml.kernel.org/r/d3b01da5-2a6-833c-6681-67a3e024a16f@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: drop mas_first_entry()

The internal function mas_first_entry() is no longer used, so drop it.

Link: https://lkml.kernel.org/r/20230711035444.526-9-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: replace mas_logical_pivot() with mas_safe_pivot()

Replace mas_logical_pivot() with mas_safe_pivot() and drop
mas_logical_pivot() since it won't be used anymore.  We can do this since
now all nodes will have node limit pivot (if it is not full node).

Link: https://lkml.kernel.org/r/20230711035444.526-8-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: update mt_validate()

Instead of using mas_first_entry() to find the leftmost leaf, use a simple
loop instead.  Remove an unneeded check for root node.  To make the error
message more accurate, check pivots first and then slots, because checking
slots depend on the node limit pivot to break the loop.

Link: https://lkml.kernel.org/r/20230711035444.526-7-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: make mas_validate_limits() check root node and node limit

Update mas_validate_limits() to check root node, check node limit pivot if
there is enough room for it to exist and check data_end.  Remove the check
for child existence as it is done in mas_validate_child_slot().

Link: https://lkml.kernel.org/r/20230711035444.526-6-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: fix mas_validate_child_slot() to check last missed slot

Don't break the loop before checking the last slot.  Also here check if
non-leaf nodes are missing children.

Link: https://lkml.kernel.org/r/20230711035444.526-5-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: make mas_validate_gaps() to check metadata

Make mas_validate_gaps() check whether the offset in the metadata points
to the largest gap.  By the way, simplify this function.

Add the verification that gaps beyond the node limit are zero.

Link: https://lkml.kernel.org/r/20230711035444.526-4-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: don't use MAPLE_ARANGE64_META_MAX to indicate no gap

Patch series "Improve the validation for maple tree and some cleanup", v2.

This patch (of 7):

Do not use a special offset to indicate that there is no gap.  When there
is no gap, offset can point to any valid slots because its gap is 0.

Link: https://lkml.kernel.org/r/20230711035444.526-1-zhangpeng.00@bytedance.com
Link: https://lkml.kernel.org/r/20230711035444.526-3-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory: pass folio into do_page_mkwrite()

Saves one implicit call to compound_head().

I'm not sure if I should change the name of the function to
do_folio_mkwrite() and update the description comment to reference a folio
as the vm_op is still called page_mkwrite.

Link: https://lkml.kernel.org/r/20230711053544.156617-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: fix race window when trying to get hugetlb folio

page_folio() is fetched before calling get_hwpoison_hugetlb_folio()
without hugetlb_lock being held.  So hugetlb page could be demoted before
get_hwpoison_hugetlb_folio() holding hugetlb_lock but after page_folio()
is fetched.  So get_hwpoison_hugetlb_folio() will hold unexpected extra
refcnt of hugetlb folio while leaving demoted page un-refcnted.

Link: https://lkml.kernel.org/r/20230711055016.2286677-9-linmiaohe@huawei.com
Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: fetch compound head after extra page refcnt is held

Page might become thp, huge page or being splited after compound head is
fetched but before page refcnt is bumped.  So hpage might be a tail page
leading to VM_BUG_ON_PAGE(PageTail(page)) in PageTransHuge().

Link: https://lkml.kernel.org/r/20230711055016.2286677-8-linmiaohe@huawei.com
Fixes: 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: minor cleanup for comments and codestyle

Fix some wrong function names and grammar error in comments. Also remove
unneeded space after for_each_process. No functional change intended.

Link: https://lkml.kernel.org/r/20230711055016.2286677-7-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: remove unneeded header files

Remove some unneeded header files. No functional change intended.

Link: https://lkml.kernel.org/r/20230711055016.2286677-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: use local variable huge to check hugetlb page

Use local variable huge to check whether page is hugetlb page to avoid
calling PageHuge() multiple times to save cpu cycles.  PageHuge() will be
stable while extra page refcnt is held.

Link: https://lkml.kernel.org/r/20230711055016.2286677-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: don't account hwpoison_filter() filtered pages

mf_generic_kill_procs() will return -EOPNOTSUPP when hwpoison_filter()
filtered dax page.  In that case, action_result() isn't expected to be
called to update mf_stats.  This will results in inaccurate but benign
memory failure handling statistics.

Link: https://lkml.kernel.org/r/20230711055016.2286677-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: ensure moving HWPoison flag to the raw error pages

If hugetlb_vmemmap_optimized is enabled, folio_clear_hugetlb_hwpoison()
called from try_memory_failure_hugetlb() won't transfer HWPoison flag to
subpages while folio's HWPoison flag is cleared.  So when trying to free
this hugetlb page into buddy, folio_clear_hugetlb_hwpoison() is not called
to move HWPoison flag from head page to the raw error pages even if now
hugetlb_vmemmap_optimized is cleared.  This will results in HWPoisoned
page being used again and raw_hwp_page leak.

Link: https://lkml.kernel.org/r/20230711055016.2286677-3-linmiaohe@huawei.com
Fixes: ac5fcde0a96a ("mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: remove unneeded PageHuge() check

Patch series "A few fixup and cleanup patches for memory-failure", v2.

This series contains a few fixup patches to fix inaccurate mf_stats, fix
race window when trying to get hugetlb folio and so on.  Also there is
minor cleanup for comments and codestyle.  More details can be found in
the respective changelogs.

This patch (of 8):

PageHuge() check in me_huge_page() is just for potential problems.  Remove
it as it's actually dead code and won't catch anything.

Link: https://lkml.kernel.org/r/20230711055016.2286677-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20230711055016.2286677-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory_hotplug: document the signal_pending() check in offline_pages()

Let's update the documentation that any signal is sufficient, and add a
comment that not only checking for fatal signals is historical baggage:
changing it now could break existing user space.  although unlikely.

For example, when an app provides a custom SIGALRM handler and triggers
memory offlining, the timeout cmd would no longer stop memory offlining,
because SIGALRM would no longer be considered a fatal signal.

Note that using signal_pending() instead of fatal_signal_pending() is
an anti-pattern, but slowly deprecating that behavior to eventually
change it in the far future is probably not worth the effort.  If this
ever becomes relevant for user-space, we might want to rethink.

Link: https://lkml.kernel.org/r/20230711174050.603820-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

HWPOISON: offline support: fix spelling in Documentation/ABI/

Correct spelling problems as identified by codespell.

Link: https://lkml.kernel.org/r/20230710052223.18254-1-rdunlap@infradead.org
Fixes: facb6011f399 ("HWPOISON: Add soft page offline support")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mm_init.c: mark check_for_memory() as __init

The only caller of check_for_memory() is free_area_init(), which is
annotated with __init, so it should be safe to also mark the former as
__init.

Link: https://lkml.kernel.org/r/20230710093750.1294-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zsmalloc: remove obj_tagged()

obj_tagged() is not needed at this point, because objects can only have
one tag: OBJ_ALLOCATED_TAG.  We needed obj_tagged() for the zsmalloc LRU
implementation, which has now been removed.  Simplify zsmalloc code and
revert to the previous implementation that was in place before the
zsmalloc LRU series.

Link: https://lkml.kernel.org/r/20230709025817.3842416-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: add uffd unit test for UFFDIO_POISON

The test is pretty basic, and exercises UFFDIO_POISON straightforwardly.
We register a region with userfaultfd, in missing fault mode.  For each
fault, we either UFFDIO_COPY a zeroed page (odd pages) or UFFDIO_POISON
(even pages).  We do this mix to test "something like a real use case",
where guest memory would be some mix of poisoned and non-poisoned pages.

We read each page in the region, and assert that the odd pages are zeroed
as expected, and the even pages yield a SIGBUS as expected.

Why UFFDIO_COPY instead of UFFDIO_ZEROPAGE?  Because hugetlb doesn't
support UFFDIO_ZEROPAGE, and we don't want to have special case code.

Link: https://lkml.kernel.org/r/20230707215540.2324998-9-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: refactor uffd_poll_thread to allow custom fault handlers

Previously, we had "one fault handler to rule them all", which used
several branches to deal with all of the scenarios required by all of the
various tests.

In upcoming patches, I plan to add a new test, which has its own slightly
different fault handling logic.  Instead of continuing to add cruft to the
existing fault handler, let's allow tests to define custom ones, separate
from other tests.

Link: https://lkml.kernel.org/r/20230707215540.2324998-8-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: document and enable new UFFDIO_POISON feature

Update the userfaultfd API to advertise this feature as part of feature
flags and supported ioctls (returned upon registration).

Add basic documentation describing the new feature.

Link: https://lkml.kernel.org/r/20230707215540.2324998-7-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: support UFFDIO_POISON for hugetlbfs

The behavior here is the same as it is for anon/shmem.  This is done
separately because hugetlb pte marker handling is a bit different.

Link: https://lkml.kernel.org/r/20230707215540.2324998-6-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: add new UFFDIO_POISON ioctl: fix

Smatch has observed that pte_offset_map_lock() is now allowed to fail, and
then ptl should not be unlocked.  Use -EAGAIN here like elsewhere.

Link: https://lkml.kernel.org/r/bc7bba61-d34f-ad3a-ccf1-c191585ef851@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: add new UFFDIO_POISON ioctl

The basic idea here is to "simulate" memory poisoning for VMs.  A VM
running on some host might encounter a memory error, after which some
page(s) are poisoned (i.e., future accesses SIGBUS).  They expect that
once poisoned, pages can never become "un-poisoned".  So, when we live
migrate the VM, we need to preserve the poisoned status of these pages.

When live migrating, we try to get the guest running on its new host as
quickly as possible.  So, we start it running before all memory has been
copied, and before we're certain which pages should be poisoned or not.

So the basic way to use this new feature is:

- On the new host, the guest's memory is registered with userfaultfd, in
  either MISSING or MINOR mode (doesn't really matter for this purpose).
- On any first access, we get a userfaultfd event. At this point we can
  communicate with the old host to find out if the page was poisoned.
- If so, we can respond with a UFFDIO_POISON - this places a swap marker
  so any future accesses will SIGBUS. Because the pte is now "present",
  future accesses won't generate more userfaultfd events, they'll just
  SIGBUS directly.

UFFDIO_POISON does not handle unmapping previously-present PTEs.  This
isn't needed, because during live migration we want to intercept all
accesses with userfaultfd (not just writes, so WP mode isn't useful for
this).  So whether minor or missing mode is being used (or both), the PTE
won't be present in any case, so handling that case isn't needed.

Similarly, UFFDIO_POISON won't replace existing PTE markers.  This might
be okay to do, but it seems to be safer to just refuse to overwrite any
existing entry (like a UFFD_WP PTE marker).

Link: https://lkml.kernel.org/r/20230707215540.2324998-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: extract file size check out into a helper

This code is already duplicated twice, and UFFDIO_POISON will do the same
check a third time.  So, it's worth extracting into a helper to save
repetitive lines of code.

Link: https://lkml.kernel.org/r/20230707215540.2324998-4-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: userfaultfd: check for start + len overflow in validate_range

Most userfaultfd ioctls take a `start + len` range as an argument.  We
have the validate_range helper to check that such ranges are valid.
However, some (but not all!) ioctls *also* check that `start + len`
doesn't wrap around (overflow).

Just check for this in validate_range.  This saves some repetitive code,
and adds the check to some ioctls which weren't bothering to check for it
before.

[axelrasmussen@google.com: call validate_range() on the src range too]
Link: https://lkml.kernel.org/r/20230714182932.2608735-1-axelrasmussen@google.com
[axelrasmussen@google.com: fix src/dst validation]
Link: https://lkml.kernel.org/r/20230810192128.1855570-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230707215540.2324998-3-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm-make-pte_marker_swapin_error-more-general-fix

fix CONFIG_MMU=n build

Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: make PTE_MARKER_SWAPIN_ERROR more general

Patch series "add UFFDIO_POISON to simulate memory poisoning with UFFD",
v4.

This series adds a new userfaultfd feature, UFFDIO_POISON. See commit 4
for a detailed description of the feature.

This patch (of 8):

Future patches will reuse PTE_MARKER_SWAPIN_ERROR to implement
UFFDIO_POISON, so make some various preparations for that:

First, rename it to just PTE_MARKER_POISONED.  The "SWAPIN" can be
confusing since we're going to re-use it for something not really related
to swap.  This can be particularly confusing for things like hugetlbfs,
which doesn't support swap whatsoever.  Also rename some various helper
functions.

Next, fix pte marker copying for hugetlbfs.  Previously, it would WARN on
seeing a PTE_MARKER_SWAPIN_ERROR, since hugetlbfs doesn't support swap.
But, since we're going to re-use it, we want it to go ahead and copy it
just like non-hugetlbfs memory does today.  Since the code to do this is
more complicated now, pull it out into a helper which can be re-used in
both places.  While we're at it, also make it slightly more explicit in
its handling of e.g.  uffd wp markers.

For non-hugetlbfs page faults, instead of returning VM_FAULT_SIGBUS for an
error entry, return VM_FAULT_HWPOISON.  For most cases this change doesn't
matter, e.g.  a userspace program would receive a SIGBUS either way.  But
for UFFDIO_POISON, this change will let KVM guests get an MCE out of the
box, instead of giving a SIGBUS to the hypervisor and requiring it to
somehow inject an MCE.

Finally, for hugetlbfs faults, handle PTE_MARKER_POISONED, and return
VM_FAULT_HWPOISON_LARGE in such cases.  Note that this can't happen today
because the lack of swap support means we'll never end up with such a PTE
anyway, but this behavior will be needed once such entries *can* show up
via UFFDIO_POISON.

Link: https://lkml.kernel.org/r/20230707215540.2324998-1-axelrasmussen@google.com
Link: https://lkml.kernel.org/r/20230707215540.2324998-2-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nadav Amit <namit@vmware.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: T.J. Alumbaugh <talumbau@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcg: minor cleanup for MEM_CGROUP_ID_MAX

MEM_CGROUP_ID_MAX is only used when CONFIG_MEMCG is configured.  So remove
unneeded !CONFIG_MEMCG variant.  Also it's only used in
mem_cgroup_alloc(), so move it from memcontrol.h to memcontrol.c.  And
further define it as:

  #define MEM_CGROUP_ID_MAX ((1UL << MEM_CGROUP_ID_SHIFT) - 1)

so if someone changes MEM_CGROUP_ID_SHIFT in the future, then
MEM_CGROUP_ID_MAX will be updated accordingly, as suggested by Muchun.

Link: https://lkml.kernel.org/r/20230708023304.1184111-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory: convert do_read_fault() to use folios

Saves one implicit call to compound_head().

Link: https://lkml.kernel.org/r/20230706163847.403202-4-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory: convert do_shared_fault() to folios

Saves three implicit calls to compound_head().

Link: https://lkml.kernel.org/r/20230706163847.403202-3-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory: convert wp_page_shared() to use folios

Saves six implicit calls to compound_head().

Link: https://lkml.kernel.org/r/20230706163847.403202-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory: convert do_page_mkwrite() to use folios

Saves one implicit call to compound_head().

Link: https://lkml.kernel.org/r/20230706163847.403202-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb_vmemmap: fix a race between vmemmap pmd split

The local variable @page in __split_vmemmap_huge_pmd() to obtain a pmd
page without holding page_table_lock may possiblely get the page table
page instead of a huge pmd page.

The effect may be in set_pte_at() since we may pass an invalid page
struct, if set_pte_at() wants to access the page struct (e.g.
CONFIG_PAGE_TABLE_CHECK is enabled), it may crash the kernel.

So fix it.  And inline __split_vmemmap_huge_pmd() since it only has one
user.

Link: https://lkml.kernel.org/r/20230707033859.16148-1-songmuchun@bytedance.com
Fixes: d8d55f5616cf ("mm: sparsemem: use page table lock to protect kernel pmd operations")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/sparse: remove redundant judgments from macro for_each_present_section_nr

next_present_section_nr() has already ensured that
'section_nr<=__highest_present_section_nr', so this check is removed.

Link: https://lkml.kernel.org/r/20230707060501.29184-1-liuq131@chinatelecom.cn
Signed-off-by: liuq <liuq131@chinatelecom.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: compaction: skip the memory hole rapidly when isolating free pages

Just like commit 9721fd82351d ("mm: compaction: skip memory hole
rapidly when isolating migratable pages"), I can see it will also take
more time to skip the larger memory hole (range: 0x1000000000 -
0x1800000000) when isolating free pages on my machine with below memory
layout.  So like commit 9721fd82351d, adding a new helper to skip the
memory hole rapidly, which can reduce the time consumed from about 70us
to less than 1us.

[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000040000000-0x00000000ffffffff]
[    0.000000]   DMA32    empty
[    0.000000]   Normal   [mem 0x0000000100000000-0x0000001fa7ffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000040000000-0x0000000fffffffff]
[    0.000000]   node   0: [mem 0x0000001800000000-0x0000001fa3c7ffff]
[    0.000000]   node   0: [mem 0x0000001fa3c80000-0x0000001fa3ffffff]
[    0.000000]   node   0: [mem 0x0000001fa4000000-0x0000001fa402ffff]
[    0.000000]   node   0: [mem 0x0000001fa4030000-0x0000001fa40effff]
[    0.000000]   node   0: [mem 0x0000001fa40f0000-0x0000001fa73cffff]
[    0.000000]   node   0: [mem 0x0000001fa73d0000-0x0000001fa745ffff]
[    0.000000]   node   0: [mem 0x0000001fa7460000-0x0000001fa746ffff]
[    0.000000]   node   0: [mem 0x0000001fa7470000-0x0000001fa758ffff]
[    0.000000]   node   0: [mem 0x0000001fa7590000-0x0000001fa7ffffff]

[shikemeng@huaweicloud.com: avoid missing last page block in section after skip offline sections]
Link: https://lkml.kernel.org/r/20230804110454.2935878-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20230804110454.2935878-2-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/d2ba7e41ee566309b594311207ffca736375fc16.1688715750.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: compaction: use the correct type of list for free pages

Use the page->buddy_list instead of page->lru to clarify the correct type
of list for free pages.

Link: https://lkml.kernel.org/r/b21cd8e2e32b9a1d9bc9e43ebf8acaf35e87f8df.1688715750.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: fix some kernel-doc comments

Add description of @mm_wr_locked and @mm.
to silence the warnings:

mm/memory.c:1716: warning: Function parameter or member 'mm_wr_locked' not described in 'unmap_vmas'
mm/memory.c:5110: warning: Function parameter or member 'mm' not described in 'mm_account_fault'

Link: https://lkml.kernel.org/r/20230707090034.125511-1-yang.lee@linux.alibaba.com
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: correct stale comment of function check_pte

Commit 2aff7a4755bed ("mm: Convert page_vma_mapped_walk to work on PFNs")
replaced page with pfns in page_vma_mapped_walk structure and updated
"@pvmw->page" to "@pvmw->pfn" in comment of function page_vma_mapped_walk.

This patch update stale "page" to "pfn" in comment of check_pte.

Link: https://lkml.kernel.org/r/20230707153953.1380615-1-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, netfs, fscache: stop read optimisation when folio removed from pagecache

Fscache has an optimisation by which reads from the cache are skipped
until we know that (a) there's data there to be read and (b) that data
isn't entirely covered by pages resident in the netfs pagecache.  This is
done with two flags manipulated by fscache_note_page_release():

if (...
    test_bit(FSCACHE_COOKIE_HAVE_DATA, &cookie->flags) &&
    test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags))
clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);

where the NO_DATA_TO_READ flag causes cachefiles_prepare_read() to
indicate that netfslib should download from the server or clear the page
instead.

The fscache_note_page_release() function is intended to be called from
->releasepage() - but that only gets called if PG_private or PG_private_2
is set - and currently the former is at the discretion of the network
filesystem and the latter is only set whilst a page is being written to
the cache, so sometimes we miss clearing the optimisation.

Fix this by following Willy's suggestion[1] and adding an address_space
flag, AS_RELEASE_ALWAYS, that causes filemap_release_folio() to always call
->release_folio() if it's set, even if PG_private or PG_private_2 aren't
set.

Note that this would require folio_test_private() and page_has_private() to
become more complicated.  To avoid that, in the places[*] where these are
used to conditionalise calls to filemap_release_folio() and
try_to_release_page(), the tests are removed the those functions just
jumped to unconditionally and the test is performed there.

[*] There are some exceptions in vmscan.c where the check guards more than
just a call to the releaser.  I've added a function, folio_needs_release()
to wrap all the checks for that.

AS_RELEASE_ALWAYS should be set if a non-NULL cookie is obtained from
fscache and cleared in ->evict_inode() before truncate_inode_pages_final()
is called.

Additionally, the FSCACHE_COOKIE_NO_DATA_TO_READ flag needs to be cleared
and the optimisation cancelled if a cachefiles object already contains data
when we open it.

[dwysocha@redhat.com: call folio_mapping() inside folio_needs_release()]
Link: https://github.com/DaveWysochanskiRH/kernel/commit/902c990e311120179fa5de99d68364b2947b79ec
Link: https://lkml.kernel.org/r/20230628104852.3391651-3-dhowells@redhat.com
Fixes: 1f67e6d0b188 ("fscache: Provide a function to note the release of a page")
Fixes: 047487c947e8 ("cachefiles: Implement the I/O routines")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Reported-by: Rohith Surabattula <rohiths.msft@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: SeongJae Park <sj@kernel.org>
Cc: Daire Byrne <daire.byrne@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steve French <sfrench@samba.org>
Cc: Shyam Prasad N <nspmangalore@gmail.com>
Cc: Rohith Surabattula <rohiths.msft@gmail.com>
Cc: Dave Wysochanski <dwysocha@redhat.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: merge folio_has_private()/filemap_release_folio() call pairs

Patch series "mm, netfs, fscache: Stop read optimisation when folio
removed from pagecache", v7.

This fixes an optimisation in fscache whereby we don't read from the cache
for a particular file until we know that there's data there that we don't
have in the pagecache.  The problem is that I'm no longer using PG_fscache
(aka PG_private_2) to indicate that the page is cached and so I don't get
a notification when a cached page is dropped from the pagecache.

The first patch merges some folio_has_private() and
filemap_release_folio() pairs and introduces a helper,
folio_needs_release(), to indicate if a release is required.

The second patch is the actual fix.  Following Willy's suggestions[1], it
adds an AS_RELEASE_ALWAYS flag to an address_space that will make
filemap_release_folio() always call ->release_folio(), even if
PG_private/PG_private_2 aren't set.  folio_needs_release() is altered to
add a check for this.

This patch (of 2):

Make filemap_release_folio() check folio_has_private().  Then, in most
cases, where a call to folio_has_private() is immediately followed by a
call to filemap_release_folio(), we can get rid of the test in the pair.

There are a couple of sites in mm/vscan.c that this can't so easily be
done.  In shrink_folio_list(), there are actually three cases (something
different is done for incompletely invalidated buffers), but
filemap_release_folio() elides two of them.

In shrink_active_list(), we don't have have the folio lock yet, so the
check allows us to avoid locking the page unnecessarily.

A wrapper function to check if a folio needs release is provided for those
places that still need to do it in the mm/ directory.  This will acquire
additional parts to the condition in a future patch.

After this, the only remaining caller of folio_has_private() outside of
mm/ is a check in fuse.

Link: https://lkml.kernel.org/r/20230628104852.3391651-1-dhowells@redhat.com
Link: https://lkml.kernel.org/r/20230628104852.3391651-2-dhowells@redhat.com
Reported-by: Rohith Surabattula <rohiths.msft@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steve French <sfrench@samba.org>
Cc: Shyam Prasad N <nspmangalore@gmail.com>
Cc: Rohith Surabattula <rohiths.msft@gmail.com>
Cc: Dave Wysochanski <dwysocha@redhat.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Xiubo Li <xiubli@redhat.com>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

rmap: pass the folio to __page_check_anon_rmap()

The lone caller already has the folio, so pass it in instead of deriving
it from the page again.

Link: https://lkml.kernel.org/r/20230706195251.2707542-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: cma: print cma name as well in cma_alloc debug

CMA allocation can happen either from global cma or from dedicated cma
region.

Thus it is helpful to print cma name as well during initial
debugging to confirm cma regions were getting initialized or not.

Link: https://lkml.kernel.org/r/1688668414-12350-1-git-send-email-quic_pintu@quicinc.com
Signed-off-by: Pintu Kumar <quic_pintu@quicinc.com>
Signed-off-by: Pintu Agarwal <pintu.ping@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove obsolete comment above struct per_cpu_pages

Since commit 01b44456a7aa ("mm/page_alloc: replace local_lock with normal
spinlock"), per_cpu_pages is protected by normal spinlock.  Remove the
obsolete comment as it's not that helpful.

Link: https://lkml.kernel.org/r/20230706092441.1574950-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

memory tier: rename destroy_memory_type() to put_memory_type()

It appears that destroy_memory_type() isn't a very good name because we
usually will not free the memory_type here.  So rename it to a more
appropriate name i.e.  put_memory_type().

Link: https://lkml.kernel.org/r/20230706063905.543800-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Suggested-by: Huang, Ying <ying.huang@intel.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Xiao Yang <yangx.jy@fujitsu.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED

Add selftest for sysctl vm.memfd_noexec is 2
(MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED)

memfd_create(.., MFD_EXEC) should fail in this case.

Link: https://lkml.kernel.org/r/20230705063315.3680666-3-jeffxu@google.com
Reported-by: Dominique Martinet <asmadeus@codewreck.org>
Closes: https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a8MaQY3Jw@mail.gmail.com/T/
Signed-off-by: Jeff Xu <jeffxu@google.com>
Cc: Daniel Verkamp <dverkamp@chromium.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: kernel test robot <lkp@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memfd: sysctl: fix MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED

Patch series "mm/memfd: fix sysctl MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED", v2.

When sysctl vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED),
memfd_create(.., MFD_EXEC) should fail.

This complies with how MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED is defined -
"memfd_create() without MFD_NOEXEC_SEAL will be rejected"

Thanks to Dominique Martinet <asmadeus@codewreck.org> who reported the bug.
see [1] for context.

[1] https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a8MaQY3Jw@mail.gmail.com/T/

This patch (of 2):

When vm.memfd_noexec is 2 (MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED),
memfd_create(.., MFD_EXEC) should fail.

This complies with how MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED is
defined - "memfd_create() without MFD_NOEXEC_SEAL will be rejected"

Link: https://lkml.kernel.org/r/20230705063315.3680666-1-jeffxu@google.com
Link: https://lkml.kernel.org/r/20230705063315.3680666-2-jeffxu@google.com
Fixes: 105ff5339f49 ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC")
Reported-by: Dominique Martinet <asmadeus@codewreck.org>
Closes: https://lore.kernel.org/linux-mm/CABi2SkXUX_QqTQ10Yx9bBUGpN1wByOi_=gZU6WEy5a8MaQY3Jw@mail.gmail.com/T/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306301351.kkbSegQW-lkp@intel.com/
Signed-off-by: Jeff Xu <jeffxu@google.com>
Cc: Daniel Verkamp <dverkamp@chromium.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs: drop_caches: draining pages before dropping caches

We expect a file page access after dropping caches should be a major
fault, but sometimes it's still a minor fault.  That's because a file page
can't be dropped if it's in a per-cpu pagevec.  Draining all pages from
per-cpu pagevec to lru list before trying to drop caches.

Link: https://lkml.kernel.org/r/20230630092203.16080-1-andrew.yang@mediatek.com
Signed-off-by: Andrew Yang <andrew.yang@mediatek.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

memcg: drop kmem.limit_in_bytes

kmem.limit_in_bytes (v1 way to limit kernel memory usage) has been
deprecated since 58056f77502f ("memcg, kmem: further deprecate
kmem.limit_in_bytes") merged in 5.16.  We haven't heard about any serious
users since then but it seems that the mere presence of the file is
causing more harm thatn good.  We (SUSE) have had several bug reports from
customers where Docker based containers started to fail because a write to
kmem.limit_in_bytes has failed.

This was unexpected because runc code only expects ENOENT (kmem disabled)
or EBUSY (tasks already running within cgroup).  So a new error code was
unexpected and the whole container startup failed.  This has been later
addressed by
https://github.com/opencontainers/runc/commit/52390d68040637dfc77f9fda6bbe70952423d380
so current Docker runtimes do not suffer from the problem anymore.  There
are still older version of Docker in use and likely hard to get rid of
completely.

Address this by wiping out the file completely and effectively get back to
pre 4.5 era and CONFIG_MEMCG_KMEM=n configuration.

I would recommend backporting to stable trees which have picked up
58056f77502f ("memcg, kmem: further deprecate kmem.limit_in_bytes").

[mhocko@suse.com: restore _KMEM switch case]
Link: https://lkml.kernel.org/r/ZKe5wxdbvPi5Cwd7@dhcp22.suse.cz
Link: https://lkml.kernel.org/r/20230704115240.14672-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_alloc: avoid false page outside zone error info

If pfn is outside zone boundaries in the first round, ret will be set to
1.  But if pfn is changed to inside the zone boundaries in zone span
seqretry path, ret is still set to 1 leading to false page outside zone
error info.

This is from code inspection.  The race window should be really small thus
hard to trigger in real world.

[akpm@linux-foundation.org: code simplification, per Matthew]
Link: https://lkml.kernel.org/r/20230704111823.940331-1-linmiaohe@huawei.com
Fixes: bdc8cb984576 ("[PATCH] memory hotplug locking: zone span seqlock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftest: add a testcase of ksm zero pages

Add a function test_unmerge_zero_page() to test the functionality on
unsharing and counting ksm-placed zero pages and counting of this patch
series.

test_unmerge_zero_page() actually contains four subjct test objects:
(1) whether the count of ksm zero pages can update correctly after merging;
(2) whether the count of ksm zero pages can update correctly after
    unmerging by madvise(...MADV_UNMERGEABLE);
(3) whether the count of ksm zero pages can update correctly after
unmerging by triggering write fault.
(4) whether ksm zero pages are really unmerged.

Link: https://lkml.kernel.org/r/20230613030947.186089-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ksm: consider KSM-placed zeropages when calculating KSM profit

When use_zero_pages is enabled, the calculation of ksm profit is not
correct because ksm zero pages is not counted in.  So update the
calculation of KSM profit including the documentation.

Link: https://lkml.kernel.org/r/20230613030942.186041-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ksm: add ksm zero pages for each process

As the number of ksm zero pages is not included in ksm_merging_pages per
process when enabling use_zero_pages, it's unclear of how many actual
pages are merged by KSM. To let users accurately estimate their memory
demands when unsharing KSM zero-pages, it's necessary to show KSM zero-
pages per process. In addition, it help users to know the actual KSM
profit because KSM-placed zero pages are also benefit from KSM.

since unsharing zero pages placed by KSM accurately is achieved, then
tracking empty pages merging and unmerging is not a difficult thing any
longer.

Since we already have /proc/<pid>/ksm_stat, just add the information of
'ksm_zero_pages' in it.

Link: https://lkml.kernel.org/r/20230613030938.185993-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ksm: count all zero pages placed by KSM

As pages_sharing and pages_shared don't include the number of zero pages
merged by KSM, we cannot know how many pages are zero pages placed by KSM
when enabling use_zero_pages, which leads to KSM not being transparent
with all actual merged pages by KSM.  In the early days of use_zero_pages,
zero-pages was unable to get unshared by the ways like MADV_UNMERGEABLE so
it's hard to count how many times one of those zeropages was then
unmerged.

But now, unsharing KSM-placed zero page accurately has been achieved, so
we can easily count both how many times a page full of zeroes was merged
with zero-page and how many times one of those pages was then unmerged.
and so, it helps to estimate memory demands when each and every shared
page could get unshared.

So we add ksm_zero_pages under /sys/kernel/mm/ksm/ to show the number
of all zero pages placed by KSM. Meanwhile, we update the Documentation.

Link: https://lkml.kernel.org/r/20230613030934.185944-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ksm: support unsharing KSM-placed zero pages

Patch series "ksm: support tracking KSM-placed zero-pages", v10.

The core idea of this patch set is to enable users to perceive the number
of any pages merged by KSM, regardless of whether use_zero_page switch has
been turned on, so that users can know how much free memory increase is
really due to their madvise(MERGEABLE) actions.  But the problem is, when
enabling use_zero_pages, all empty pages will be merged with kernel zero
pages instead of with each other as use_zero_pages is disabled, and then
these zero-pages are no longer monitored by KSM.

The motivations to do this is seen at:
https://lore.kernel.org/lkml/202302100915227721315@zte.com.cn/

In one word, we hope to implement the support for KSM-placed zero pages
tracking without affecting the feature of use_zero_pages, so that app
developer can also benefit from knowing the actual KSM profit by getting
KSM-placed zero pages to optimize applications eventually when
/sys/kernel/mm/ksm/use_zero_pages is enabled.

This patch (of 5):

When use_zero_pages of ksm is enabled, madvise(addr, len,
MADV_UNMERGEABLE) and other ways (like write 2 to /sys/kernel/mm/ksm/run)
to trigger unsharing will *not* actually unshare the shared zeropage as
placed by KSM (which is against the MADV_UNMERGEABLE documentation).  As
these KSM-placed zero pages are out of the control of KSM, the related
counts of ksm pages don't expose how many zero pages are placed by KSM
(these special zero pages are different from those initially mapped zero
pages, because the zero pages mapped to MADV_UNMERGEABLE areas are
expected to be a complete and unshared page).

To not blindly unshare all shared zero_pages in applicable VMAs, the patch
use pte_mkdirty (related with architecture) to mark KSM-placed zero pages.
Thus, MADV_UNMERGEABLE will only unshare those KSM-placed zero pages.

In addition, we'll reuse this mechanism to reliably identify KSM-placed
ZeroPages to properly account for them (e.g., calculating the KSM profit
that includes zeropages) in the latter patches.

The patch will not degrade the performance of use_zero_pages as it doesn't
change the way of merging empty pages in use_zero_pages's feature.

Link: https://lkml.kernel.org/r/202306131104554703428@zte.com.cn
Link: https://lkml.kernel.org/r/20230613030928.185882-1-yang.yang29@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate_device: try to handle swapcache pages

Migrating file pages and swapcache pages into device memory is not
supported.  Try to get rid of the swap cache, and if successful, go ahead
as with other anonymous pages.

Link: https://lkml.kernel.org/r/20230607172944.11713-1-mpenttil@redhat.com
Signed-off-by: Mika Penttilä <mpenttil@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests: cgroup: add zswap-memcg unwanted writeback test

Add a test to verify that when a memcg hits its limit in zswap, it doesn't
trigger an unwanted writeback that would result in pages not owned by that
memcg to be sent to disk, even if zswap isn't full.  This was fixed by
commit 0bdf0efa180a("zswap: do not shrink if cgroup may not zswap").

Link: https://lkml.kernel.org/r/20230621153548.428093-4-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests: cgroup: add test_zswap with no kmem bypass test

Add a cgroup selftest that verifies memcg charging in zswap.  The original
issue was that kmem bypass was applied to pages swapped out to zswap by
kswapd, resulting in zswapped memory not being charged.  It was fixed by
commit cd08d80ecdac("mm: correctly charge compressed memory to its
memcg").

Link: https://lkml.kernel.org/r/20230621153548.428093-3-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests: cgroup: add test_zswap program

Patch series "selftests: cgroup: add zswap test program".

This series adds 2 zswap related selftests that verify known and fixed
issues.  A new dedicated test program (test_zswap) is proposed since the
test cases are specific to zswap and hosts specific helpers.

The first patch adds the (empty) test program, while the other 2 add an
actual test function each.

This patch (of 3):

Add empty cgroup-zswap self test scaffold program, test functions to be
added in the next commits.

Link: https://lkml.kernel.org/r/20230621153548.428093-1-cerasuolodomenico@gmail.com
Link: https://lkml.kernel.org/r/20230621153548.428093-2-cerasuolodomenico@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: use write_seqlock_irqsave() instead write_seqlock() + local_irq_save().

__build_all_zonelists() acquires zonelist_update_seq by first disabling
interrupts via local_irq_save() and then acquiring the seqlock with
write_seqlock().  This is troublesome and leads to problems on PREEMPT_RT.
The problem is that the inner spinlock_t becomes a sleeping lock on
PREEMPT_RT and must not be acquired with disabled interrupts.

The API provides write_seqlock_irqsave() which does the right thing in one
step.  printk_deferred_enter() has to be invoked in non-migrate-able
context to ensure that deferred printing is enabled and disabled on the
same CPU.  This is the case after zonelist_update_seq has been acquired.

There was discussion on the first submission that the order should be:
local_irq_disable();
printk_deferred_enter();
write_seqlock();

to avoid pitfalls like having an unaccounted printk() coming from
write_seqlock_irqsave() before printk_deferred_enter() is invoked.  The
only origin of such a printk() can be a lockdep splat because the lockdep
annotation happens after the sequence count is incremented.  This is
exceptional and subject to change.

It was also pointed that PREEMPT_RT can be affected by the printk problem
since its write_seqlock_irqsave() does not really disable interrupts.
This isn't the case because PREEMPT_RT's printk implementation differs
from the mainline implementation in two important aspects:

- Printing happens in a dedicated threads and not at during the
  invocation of printk().
- In emergency cases where synchronous printing is used, a different
  driver is used which does not use tty_port::lock.

Acquire zonelist_update_seq with write_seqlock_irqsave() and then defer
printk output.

Link: https://lkml.kernel.org/r/20230623201517.yw286Knb@linutronix.de
Fixes: 1007843a91909 ("mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zsmalloc: remove zs_compact_control

__zs_compact always putback src_zspage into class list after
migrate_zspage.  Thus, we don't need to keep last position of src_zspage
any more.  Let's remove it.

Link: https://lkml.kernel.org/r/20230624053120.643409-4-senozhatsky@chromium.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zsmalloc: move migration destination zspage inuse check

Destination zspage fullness check need to be done after zs_object_copy()
because that's where source and destination zspages fullness change.
Checking destination zspage fullness before zs_object_copy() may cause
migration to loop through source zspage sub-pages scanning for allocate
objects just to find out at the end that the destination zspage is full.

Link: https://lkml.kernel.org/r/20230624053120.643409-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zsmalloc: do not scan for allocated objects in empty zspage

Patch series "zsmalloc: small compaction improvements", v2.

A tiny series that can reduce the number of find_alloced_obj() invocations
(which perform a linear scan of sub-page) during compaction.  Inspired by
Alexey Romanov's findings.

This patch (of 3):

zspage migration can terminate as soon as it moves the last allocated
object from the source zspage.  Add a simple helper zspage_empty() that
tests zspage ->inuse on each migration iteration.

Link: https://lkml.kernel.org/r/20230624053120.643409-2-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: Alexey Romanov <AVRomanov@sberdevices.ru>
Reviewed-by: Alexey Romanov <avromanov@sberdevices.ru>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mm_init.c: remove obsolete macro HASH_SMALL

HASH_SMALL only works when parameter numentries is 0. But the sole caller
futex_init() never calls alloc_large_system_hash() with numentries set to
0. So HASH_SMALL is obsolete and remove it.

Link: https://lkml.kernel.org/r/20230625021323.849147-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: André Almeida <andrealmeid@igalia.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: fix min_free_kbytes calculation regarding ZONE_MOVABLE

The current calculation of min_free_kbytes only uses ZONE_DMA and
ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN] will
also divide part of min_free_kbytes.This will cause the min watermark of
ZONE_NORMAL to be too small in the presence of ZONE_MOVEABLE.

__GFP_HIGH and PF_MEMALLOC allocations usually don't need movable zone
pages, so just like ZONE_HIGHMEM, cap pages_min to a small value in
__setup_per_zone_wmarks().

On my testing machine with 16GB of memory (transparent hugepage is turned
off by default, and movablecore=12G is configured) The following is a
comparative test data of watermark_min

no patch add patch
ZONE_DMA 1 8
ZONE_DMA32 151 709
ZONE_NORMAL 233 1113
ZONE_MOVABLE 1434 128
min_free_kbytes 7288 7326

Link: https://lkml.kernel.org/r/20230625031656.23941-1-liuq131@chinatelecom.cn
Signed-off-by: liuq <liuq131@chinatelecom.cn>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs: convert block_commit_write to return void

block_commit_write() always returns 0, this patch changes it to return
void.

Link: https://lkml.kernel.org/r/20230626055518.842392-3-beanhuo@iokpp.de
Signed-off-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Luís Henriques <ocfs2-devel@oss.oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/buffer: clean up block_commit_write

Originally inode is used to get blksize, after commit 45bce8f3e343
("fs/buffer.c: make block-size be per-page and protected by the page
lock"), __block_commit_write no longer uses this parameter inode.

[akpm@linux-foundation.org: remove now-unused local `inode']
Link: https://lkml.kernel.org/r/20230626055518.842392-2-beanhuo@iokpp.de
Signed-off-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Luís Henriques <ocfs2-devel@oss.oracle.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: remove unneeded 'inline' annotation

Remove unneeded 'inline' annotation from num_poisoned_pages_inc() and
num_poisoned_pages_sub().  No functional change intended.

Link: https://lkml.kernel.org/r/20230626114343.1846587-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

memory tier: use helper function destroy_memory_type()

Use helper function destroy_memory_type() to release memtype instead of
open code it to help improve code readability a bit.  No functional change
intended.

Link: https://lkml.kernel.org/r/20230626121053.1916447-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Wei Xu <weixugc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory-failure: remove unneeded page state check in shake_page()

Remove unneeded PageLRU(p) and is_free_buddy_page(p) check as slab caches
are not shrunk now.  This check can be added back when a lightweight range
based shrinker is available.

Link: https://lkml.kernel.org/r/20230628014929.3441386-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: add a fast path case in mas_wr_slot_store()

When expanding a range in two directions, only partially overwriting the
previous and next ranges, the number of entries will not be increased, so
we can just update the pivots as a fast path. However, it may introduce
potential risks in RCU mode, because it updates two pivots. We only
enable it in non-RCU mode.

Link: https://lkml.kernel.org/r/20230628073657.75314-5-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: optimize mas_wr_append(), also improve duplicating VMAs

When the new range can be completely covered by the original last range
without touching the boundaries on both sides, two new entries can be
appended to the end as a fast path. We update the original last pivot at
the end, and the newly appended two entries will not be accessed before
this, so it is also safe in RCU mode.

This is useful for sequential insertion, which is what we do in
dup_mmap(). Enabling BENCH_FORK in test_maple_tree and just running
bench_forking() gives the following time-consuming numbers:

before:               after:
17,874.83 msec        15,738.38 msec

It shows about a 12% performance improvement for duplicating VMAs.

Link: https://lkml.kernel.org/r/20230628073657.75314-4-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: add test for expanding range in RCU mode

Add test for expanding range in RCU mode. If we use the fast path of the
slot store to expand range in RCU mode, this test will fail.

Link: https://lkml.kernel.org/r/20230628073657.75314-3-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

maple_tree: add test for mas_wr_modify() fast path

Patch series "Optimize the fast path of mas_store()", v4.

Add fast paths for mas_wr_append() and mas_wr_slot_store() respectively.
The newly added fast path of mas_wr_append() is used in fork() and how
much it benefits fork() depends on how many VMAs are duplicated.

Thanks Liam for the review.

This patch (of 4):

Add tests for all cases of mas_wr_append() and mas_wr_slot_store().

Link: https://lkml.kernel.org/r/20230628073657.75314-1-zhangpeng.00@bytedance.com
Link: https://lkml.kernel.org/r/20230628073657.75314-2-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/filemap.c: fix update prev_pos after one read request done

ra->prev_pos tracks the last visited byte in the previous read request.
It is used to check whether it is sequential read in ondemand_readahead
and thus affects the readahead window.

After commit 06c0444290ce ("mm/filemap.c: generic_file_buffered_read() now
uses find_get_pages_contig"), update logic of prev_pos is changed.  It
updates prev_pos after each return from filemap_get_pages().  But the read
request from user may be not fully completed at this point.  The updated
prev_pos impacts the subsequent readahead window.

The real problem is performance drop of fsck_msdos between linux-5.4 and
linux-5.15(also linux-6.4).  Comparing to linux-5.4,It spends about 110%
time and read 140% pages.  The read pattern of fsck_msdos is not fully
sequential.

Simplified read pattern of fsck_msdos likes below:
1.read at page offset 0xa,size 0x1000
2.read at other page offset like 0x20,size 0x1000
3.read at page offset 0xa,size 0x4000
4.read at page offset 0xe,size 0x1000

Here is the read status on linux-6.4:
1.after read at page offset 0xa,size 0x1000
    ->page ofs 0xa go into pagecache
2.after read at page offset 0x20,size 0x1000
    ->page ofs 0x20 go into pagecache
3.read at page offset 0xa,size 0x4000
    ->filemap_get_pages read ofs 0xa from pagecache and returns
    ->prev_pos is updated to 0xb and goto next loop
    ->filemap_get_pages tends to read ofs 0xb,size 0x3000
    ->initial_readahead case in ondemand_readahead since prev_pos is
      the same as request ofs.
    ->read 8 pages while async size is 5 pages
      (PageReadahead flag at page 0xe)
4.read at page offset 0xe,size 0x1000
    ->hit page 0xe with PageReadahead flag set,double the ra_size.
      read 16 pages while async size is 16 pages
Now it reads 24 pages while actually uses 5 pages

on linux-5.4:
1.the same as 6.4
2.the same as 6.4
3.read at page offset 0xa,size 0x4000
    ->read ofs 0xa from pagecache
    ->read ofs 0xb,size 0x3000 using page_cache_sync_readahead
      read 3 pages
    ->prev_pos is updated to 0xd before generic_file_buffered_read
      returns
4.read at page offset 0xe,size 0x1000
    ->initial_readahead case in ondemand_readahead since
      request ofs-prev_pos==1
    ->read 4 pages while async size is 3 pages

Now it reads 7 pages while actually uses 5 pages.

In above demo, the initial_readahead case is triggered by offset of user
request on linux-5.4.  While it may be triggered by update logic of
prev_pos on linux-6.4.

To fix the performance drop, update prev_pos after finishing one read
request.

Link: https://lkml.kernel.org/r/20230628110220.120134-1-haibo.li@mediatek.com
Signed-off-by: Haibo Li <haibo.li@mediatek.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: add gup test matrix in run_vmtests.sh

Add a matrix for testing gup based on the current gup_test.  Only run the
matrix when -a is specified because it's a bit slow.

It covers:

  - Different types of huge pages: thp, hugetlb, or no huge page
  - Permissions: Write / Read-only
  - Fast-gup, with/without
  - Types of the GUP: pin / gup / longterm pins
  - Shared / Private memories
  - GUP size: 1 / 512 / random page sizes

Link: https://lkml.kernel.org/r/20230628215310.73782-9-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/mm: add -a to run_vmtests.sh

Allows to specify optional tests in run_vmtests.sh, where we can run time
consuming test matrix only when user specified "-a".

Link: https://lkml.kernel.org/r/20230628215310.73782-8-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup: retire follow_hugetlb_page()

Now __get_user_pages() should be well prepared to handle thp completely,
as long as hugetlb gup requests even without the hugetlb's special path.

Time to retire follow_hugetlb_page().

Tweak misc comments to reflect reality of follow_hugetlb_page()'s removal.

Link: https://lkml.kernel.org/r/20230628215310.73782-7-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup: accelerate thp gup even for "pages != NULL"

The acceleration of THP was done with ctx.page_mask, however it'll be
ignored if **pages is non-NULL.

The old optimization was introduced in 2013 in 240aadeedc4a ("mm:
accelerate mm_populate() treatment of THP pages").  It didn't explain why
we can't optimize the **pages non-NULL case.  It's possible that at that
time the major goal was for mm_populate() which should be enough back
then.

Optimize thp for all cases, by properly looping over each subpage, doing
cache flushes, and boost refcounts / pincounts where needed in one go.

This can be verified using gup_test below:

  # chrt -f 1 ./gup_test -m 512 -t -L -n 1024 -r 10

Before:    13992.50 ( +-8.75%)
After:       378.50 (+-69.62%)

Link: https://lkml.kernel.org/r/20230628215310.73782-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup: cleanup next_page handling

The only path that doesn't use generic "**pages" handling is the gate vma.
Make it use the same path, meanwhile tune the next_page label upper to
cover "**pages" handling.  This prepares for THP handling for "**pages".

Link: https://lkml.kernel.org/r/20230628215310.73782-5-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A . Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>