mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate

The hugepage_vma_revalidate() needs to check if the vma is still anonymous
vma or not since the address may be unmapped then remapped to file before
khugepaged reaquired the mmap_lock.

The old comment is not quite helpful, elaborate this with better comment.

Link: https://lkml.kernel.org/r/20220616174840.1202070-4-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: thp: consolidate vma size check to transhuge_vma_suitable

There are couple of places that check whether the vma size is ok for THP
or whether address fits, they are open coded and duplicate, use
transhuge_vma_suitable() to do the job by passing in (vma->end -
HPAGE_PMD_SIZE).

Move vma size check into hugepage_vma_check().  This will make
khugepaged_enter() is as same as khugepaged_enter_vma().  There is just
one caller for khugepaged_enter(), replace it to khugepaged_enter_vma()
and remove khugepaged_enter().

Link: https://lkml.kernel.org/r/20220616174840.1202070-3-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: khugepaged: check THP flag in hugepage_vma_check()

Patch series "Cleanup transhuge_xxx helpers", v5.

This series is the follow-up of the discussion about cleaning up
transhuge_xxx helpers at
https://lore.kernel.org/linux-mm/627a71f8-e879-69a5-ceb3-fc8d29d2f7f1@suse.cz/.

THP has a bunch of helpers that do VMA sanity check for different paths,
they do the similar checks for the most callsites and have a lot duplicate
codes.  And it is confusing what helpers should be used at what
conditions.

This series reorganized and cleaned up the code so that we could
consolidate all the checks into hugepage_vma_check().

The transhuge_vma_enabled(), transparent_hugepage_active() and
__transparent_hugepage_enabled() are killed by this series.

This patch (of 7):

Currently the THP flag check in hugepage_vma_check() will fallthrough if
the flag is NEVER and VM_HUGEPAGE is set.  This is not a problem for now
since all the callers have the flag checked before or can't be invoked if
the flag is NEVER.

However, the following patch will call hugepage_vma_check() in more
places, for example, page fault, so this flag must be checked in
hugepge_vma_check().

Link: https://lkml.kernel.org/r/20220616174840.1202070-1-shy828301@gmail.com
Link: https://lkml.kernel.org/r/20220616174840.1202070-2-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

xfs: add dax dedupe support

Introduce xfs_mmaplock_two_inodes_and_break_dax_layout() for dax files who
are going to be deduped.  After that, call compare range function only
when files are both DAX or not.

Link: https://lkml.kernel.org/r/20220603053738.1218681-15-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

xfs: support CoW in fsdax mode

In fsdax mode, WRITE and ZERO on a shared extent need CoW performed.
After that, new allocated extents needs to be remapped to the file.  So,
add a CoW identification in ->iomap_begin(), and implement ->iomap_end()
to do the remapping work.

[akpm@linux-foundation.org: make xfs_dax_fault() static]
Link: https://lkml.kernel.org/r/20220603053738.1218681-14-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: dedup file range to use a compare function

With dax we cannot deal with readpage() etc.  So, we create a dax
comparison function which is similar with vfs_dedupe_file_range_compare().
And introduce dax_remap_file_range_prep() for filesystem use.

Link: https://lkml.kernel.org/r/20220603053738.1218681-13-ruansy.fnst@fujitsu.com
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: add dax_iomap_cow_copy() for dax zero

Punch hole on a reflinked file needs dax_iomap_cow_copy() too.  Otherwise,
data in not aligned area will be not correct.  So, add the CoW operation
for not aligned case in dax_memzero().

Link: https://lkml.kernel.org/r/20220603053738.1218681-12-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: replace mmap entry in case of CoW

Replace the existing entry to the newly allocated one in case of CoW.
Also, we mark the entry as PAGECACHE_TAG_TOWRITE so writeback marks this
entry as writeprotected.  This helps us snapshots so new write pagefaults
after snapshots trigger a CoW.

Link: https://lkml.kernel.org/r/20220603053738.1218681-11-ruansy.fnst@fujitsu.com
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: introduce dax_iomap_cow_copy()

In the case where the iomap is a write operation and iomap is not equal to
srcmap after iomap_begin, we consider it is a CoW operation.

In this case, the destination (iomap->addr) points to a newly allocated
extent.  It is needed to copy the data from srcmap to the extent.  In
theory, it is better to copy the head and tail ranges which is outside of
the non-aligned area instead of copying the whole aligned range.  But in
dax page fault, it will always be an aligned range.  So copy the whole
range in this case.

Link: https://lkml.kernel.org/r/20220603053738.1218681-10-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: output address in dax_iomap_pfn() and rename it

Add address output in dax_iomap_pfn() in order to perform a memcpy() in
CoW case.  Since this function both output address and pfn, rename it to
dax_iomap_direct_access().

[ruansy.fnst@fujitsu.com: initialize `rc', per Dan]
Link: https://lore.kernel.org/linux-fsdevel/Yp8FUZnO64Qvyx5G@kili/
Link: https://lkml.kernel.org/r/20220607143837.161174-1-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/20220603053738.1218681-9-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: set a CoW flag when associate reflink mappings

Introduce a PAGE_MAPPING_DAX_COW flag to support association with CoW file
mappings.  In this case, since the dax-rmap has already took the
responsibility to look up for shared files by given dax page, the
page->mapping is no longer to used for rmap but for marking that this dax
page is shared.  And to make sure disassociation works fine, we use
page->index as refcount, and clear page->mapping to the initial state when
page->index is decreased to 0.

With the help of this new flag, it is able to distinguish normal case and
CoW case, and keep the warning in normal case.

Link: https://lkml.kernel.org/r/20220603053738.1218681-8-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

xfs: implement ->notify_failure() for XFS

Introduce xfs_notify_failure.c to handle failure related works, such as
implement ->notify_failure(), register/unregister dax holder in xfs, and
so on.

If the rmap feature of XFS enabled, we can query it to find files and
metadata which are associated with the corrupt data.  For now all we do is
kill processes with that file mapped into their address spaces, but future
patches could actually do something about corrupt metadata.

After that, the memory failure needs to notify the processes who are using
those files.

Link: https://lkml.kernel.org/r/20220603053738.1218681-7-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: introduce mf_dax_kill_procs() for fsdax case

This new function is a variant of mf_generic_kill_procs that accepts a
file, offset pair instead of a struct to support multiple files sharing a
DAX mapping.  It is intended to be called by the file systems as part of
the memory_failure handler after the file system performed a reverse
mapping from the storage address to the file and file offset.

Link: https://lkml.kernel.org/r/20220603053738.1218681-6-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fsdax: introduce dax_lock_mapping_entry()

The current dax_lock_page() locks dax entry by obtaining mapping and index
in page.  To support 1-to-N RMAP in NVDIMM, we need a new function to lock
a specific dax entry corresponding to this file's mapping,index.  And
output the page corresponding to the specific dax entry for caller use.

Link: https://lkml.kernel.org/r/20220603053738.1218681-5-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

pagemap,pmem: introduce ->memory_failure()

When memory-failure occurs, we call this function which is implemented by
each kind of devices.  For the fsdax case, pmem device driver implements
it.  Pmem device driver will find out the filesystem in which the
corrupted page located in.

With dax_holder notify support, we are able to notify the memory failure
from pmem driver to upper layers.  If there is something not support in
the notify routine, memory_failure will fall back to the generic hanlder.

Link: https://lkml.kernel.org/r/20220603053738.1218681-4-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: factor helpers for memory_failure_dev_pagemap

memory_failure_dev_pagemap code is a bit complex before introduce RMAP
feature for fsdax.  So it is needed to factor some helper functions to
simplify these code.

[akpm@linux-foundation.org: fix CONFIG_HUGETLB_PAGE=n build]
[zhengbin13@huawei.com: fix redefinition of mf_generic_kill_procs]
Link: https://lkml.kernel.org/r/20220628112143.1170473-1-zhengbin13@huawei.com
Link: https://lkml.kernel.org/r/20220603053738.1218681-3-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.wiliams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

dax: introduce holder for dax_device

Patch series "v14 fsdax-rmap + v11 fsdax-reflink", v2.

The patchset fsdax-rmap is aimed to support shared pages tracking for
fsdax.

It moves owner tracking from dax_assocaite_entry() to pmem device driver,
by introducing an interface ->memory_failure() for struct pagemap.  This
interface is called by memory_failure() in mm, and implemented by pmem
device.

Then call holder operations to find the filesystem which the corrupted
data located in, and call filesystem handler to track files or metadata
associated with this page.

Finally we are able to try to fix the corrupted data in filesystem and do
other necessary processing, such as killing processes who are using the
files affected.

The call trace is like this:
memory_failure()
|* fsdax case
|------------
|pgmap->ops->memory_failure()      => pmem_pgmap_memory_failure()
| dax_holder_notify_failure()      =>
|  dax_device->holder_ops->notify_failure() =>
|                                     - xfs_dax_notify_failure()
|  |* xfs_dax_notify_failure()
|  |--------------------------
|  |   xfs_rmap_query_range()
|  |    xfs_dax_failure_fn()
|  |    * corrupted on metadata
|  |       try to recover data, call xfs_force_shutdown()
|  |    * corrupted on file data
|  |       try to recover data, call mf_dax_kill_procs()
|* normal case
|-------------
|mf_generic_kill_procs()

The patchset fsdax-reflink attempts to add CoW support for fsdax, and
takes XFS, which has both reflink and fsdax features, as an example.

One of the key mechanisms needed to be implemented in fsdax is CoW.  Copy
the data from srcmap before we actually write data to the destination
iomap.  And we just copy range in which data won't be changed.

Another mechanism is range comparison.  In page cache case, readpage() is
used to load data on disk to page cache in order to be able to compare
data.  In fsdax case, readpage() does not work.  So, we need another
compare data with direct access support.

With the two mechanisms implemented in fsdax, we are able to make reflink
and fsdax work together in XFS.

This patch (of 14):

To easily track filesystem from a pmem device, we introduce a holder for
dax_device structure, and also its operation.  This holder is used to
remember who is using this dax_device:

 - When it is the backend of a filesystem, the holder will be the
   instance of this filesystem.
 - When this pmem device is one of the targets in a mapped device, the
   holder will be this mapped device.  In this case, the mapped device
   has its own dax_device and it will follow the first rule.  So that we
   can finally track to the filesystem we needed.

The holder and holder_ops will be set when filesystem is being mounted,
or an target device is being activated.

Link: https://lkml.kernel.org/r/20220603053738.1218681-1-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/20220603053738.1218681-2-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.wiliams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.com>
Cc: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools: add selftests to hmm for COW in device memory

The objective is to test device migration mechanism in pages marked as
COW, for private and coherent device type.  In case of writing to COW
private page(s), a page fault will migrate pages back to system memory
first.  Then, these pages will be duplicated.  In case of COW device
coherent type, pages are duplicated directly from device memory.

Link: https://lkml.kernel.org/r/20220715150521.18165-15-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools: add hmm gup tests for device coherent type

The intention is to test hmm device coherent type under different get user
pages paths.  Also, test gup with FOLL_LONGTERM flag set in device
coherent pages.  These pages should get migrated back to system memory.

Link: https://lkml.kernel.org/r/20220715150521.18165-14-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools: update test_hmm script to support SP config

Add two more parameters to set spm_addr_dev0 & spm_addr_dev1 addresses.
These two parameters configure the start SP addresses for each device in
test_hmm driver.  Consequently, this configures zone device type as
coherent.

Link: https://lkml.kernel.org/r/20220715150521.18165-13-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools: update hmm-test to support device coherent type

Test cases such as migrate_fault and migrate_multiple, were modified to
explicit migrate from device to sys memory without the need of page
faults, when using device coherent type.

Snapshot test case updated to read memory device type first and based on
that, get the proper returned results migrate_ping_pong test case added to
test explicit migration from device to sys memory for both private and
coherent zone types.

Helpers to migrate from device to sys memory and vicerversa were also
added.

Link: https://lkml.kernel.org/r/20220715150521.18165-12-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib: add support for device coherent type in test_hmm

Device Coherent type uses device memory that is coherently accesible by
the CPU.  This could be shown as SP (special purpose) memory range at the
BIOS-e820 memory enumeration.  If no SP memory is supported in system,
this could be faked by setting CONFIG_EFI_FAKE_MEMMAP.

Currently, test_hmm only supports two different SP ranges of at least
256MB size. This could be specified in the kernel parameter variable
efi_fake_mem. Ex. Two SP ranges of 1GB starting at 0x100000000 &
0x140000000 physical address. Ex.
efi_fake_mem=1G@0x100000000:0x40000,1G@0x140000000:0x40000

Private and coherent device mirror instances can be created in the same
probed.  This is done by passing the module parameters spm_addr_dev0 &
spm_addr_dev1.  In this case, it will create four instances of
device_mirror.  The first two correspond to private device type, the last
two to coherent type.  Then, they can be easily accessed from user space
through /dev/hmm_mirror<num_device>.  Usually num_device 0 and 1 are for
private, and 2 and 3 for coherent types.  If no module parameters are
passed, two instances of private type device_mirror will be created only.

Link: https://lkml.kernel.org/r/20220715150521.18165-11-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib: test_hmm add module param for zone device type

In order to configure device coherent in test_hmm, two module parameters
should be passed, which correspond to the SP start address of each device
(2) spm_addr_dev0 & spm_addr_dev1.  If no parameters are passed, private
device type is configured.

Link: https://lkml.kernel.org/r/20220715150521.18165-10-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib: test_hmm add ioctl to get zone device type

Add new ioctl cmd to query zone device type.  This will be used once the
test_hmm adds zone device coherent type.

Link: https://lkml.kernel.org/r/20220715150521.18165-9-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drm/amdkfd: add SPM support for SVM

When CPU is connected throug XGMI, it has coherent access to VRAM
resource.  In this case that resource is taken from a table in the device
gmc aperture base.  This resource is used along with the device type,
which could be DEVICE_PRIVATE or DEVICE_COHERENT to create the device page
map region.

Also, MIGRATE_VMA_SELECT_DEVICE_COHERENT flag is selected for coherent
type case during migration to device.

Link: https://lkml.kernel.org/r/20220715150521.18165-8-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/gup: migrate device coherent pages when pinning instead of failing

Currently any attempts to pin a device coherent page will fail.  This is
because device coherent pages need to be managed by a device driver, and
pinning them would prevent a driver from migrating them off the device.

However this is no reason to fail pinning of these pages.  These are
coherent and accessible from the CPU so can be migrated just like pinning
ZONE_MOVABLE pages.  So instead of failing all attempts to pin them first
try migrating them out of ZONE_DEVICE.

[hch@lst.de: rebased to the split device memory checks, moved migrate_device_page to migrate_device.c]
Link: https://lkml.kernel.org/r/20220715150521.18165-7-alex.sierra@amd.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add device coherent vma selection for memory migration

This case is used to migrate pages from device memory, back to system
memory.  Device coherent type memory is cache coherent from device and CPU
point of view.

Link: https://lkml.kernel.org/r/20220715150521.18165-6-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Poppple <apopple@nvidia.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: handling Non-LRU pages returned by vm_normal_pages

With DEVICE_COHERENT, we'll soon have vm_normal_pages() return
device-managed anonymous pages that are not LRU pages.  Although they
behave like normal pages for purposes of mapping in CPU page, and for COW.
They do not support LRU lists, NUMA migration or THP.

Callers to follow_page() currently don't expect ZONE_DEVICE pages,
however, with DEVICE_COHERENT we might now return ZONE_DEVICE.  Check for
ZONE_DEVICE pages in applicable users of follow_page() as well.

Link: https://lkml.kernel.org/r/20220715150521.18165-5-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> [v2]
Reviewed-by: Alistair Popple <apopple@nvidia.com> [v6]
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add zone device coherent type memory support

Device memory that is cache coherent from device and CPU point of view.
This is used on platforms that have an advanced system bus (like CAPI or
CXL).  Any page of a process can be migrated to such memory.  However, no
one should be allowed to pin such memory so that it can always be evicted.

[hch@lst.de: rebased ontop of the refcount changes, remove is_dev_private_or_coherent_page]
Link: https://lkml.kernel.org/r/20220715150521.18165-4-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: move page zone helpers from mm.h to mmzone.h

It makes more sense to have these helpers in zone specific header
file, rather than the generic mm.h

Link: https://lkml.kernel.org/r/20220715150521.18165-3-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: rename is_pinnable_page() to is_longterm_pinnable_page()

Patch series "Add MEMORY_DEVICE_COHERENT for coherent device memory
mapping", v9.

This patch series introduces MEMORY_DEVICE_COHERENT, a type of memory
owned by a device that can be mapped into CPU page tables like
MEMORY_DEVICE_GENERIC and can also be migrated like MEMORY_DEVICE_PRIVATE.

This patch series is mostly self-contained except for a few places where
it needs to update other subsystems to handle the new memory type.

System stability and performance are not affected according to our ongoing
testing, including xfstests.

How it works: The system BIOS advertises the GPU device memory (aka VRAM)
as SPM (special purpose memory) in the UEFI system address map.

The amdgpu driver registers the memory with devmap as
MEMORY_DEVICE_COHERENT using devm_memremap_pages.  The initial user for
this hardware page migration capability is the Frontier supercomputer
project.  This functionality is not AMD-specific.  We expect other GPU
vendors to find this functionality useful, and possibly other hardware
types in the future.

Our test nodes in the lab are similar to the Frontier configuration, with
.5 TB of system memory plus 256 GB of device memory split across 4 GPUs,
all in a single coherent address space.  Page migration is expected to
improve application efficiency significantly.  We will report empirical
results as they become available.

Coherent device type pages at gup are now migrated back to system memory
if they are being pinned long-term (FOLL_LONGTERM).  The reason is, that
long-term pinning would interfere with the device memory manager owning
the device-coherent pages (e.g.  evictions in TTM).  These series
incorporate Alistair Popple patches to do this migration from
pin_user_pages() calls.  hmm_gup_test has been added to hmm-test to test
different get user pages calls.

This series includes handling of device-managed anonymous pages returned
by vm_normal_pages.  Although they behave like normal pages for purposes
of mapping in CPU page tables and for COW, they do not support LRU lists,
NUMA migration or THP.

We also introduced a FOLL_LRU flag that adds the same behaviour to
follow_page and related APIs, to allow callers to specify that they expect
to put pages on an LRU list.

This patch (of 14):

is_pinnable_page() and folio_is_pinnable() are renamed to
is_longterm_pinnable_page() and folio_is_longterm_pinnable() respectively.
These functions are used in the FOLL_LONGTERM flag context.

Link: https://lkml.kernel.org/r/20220715150521.18165-1-alex.sierra@amd.com
Link: https://lkml.kernel.org/r/20220715150521.18165-2-alex.sierra@amd.com
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/vm: add protection_keys tests to run_vmtests

Add "protected_keys" tests to "run_vmtests.sh" would help run all VM
related tests from a single shell script.

[kalpana.shetty@amd.com: Shuah Khan's review comments incorporated, added -x executable check]
Link: https://lkml.kernel.org/r/20220617202931.357-1-kalpana.shetty@amd.com
Link: https://lkml.kernel.org/r/20220610090704.296-1-kalpana.shetty@amd.com
Link: https://lkml.kernel.org/r/20220531102556.388-1-kalpana.shetty@amd.com
Signed-off-by: Kalpana Shetty <kalpana.shetty@amd.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/lru_sort: fix potential memory leak in damon_lru_sort_init()

damon_lru_sort_init() returns an error when damon_select_ops() fails
without freeing 'ctx' which allocated before.  This commit fixes the
potential memory leak by freeing 'ctx' under the situation.

Link: https://lkml.kernel.org/r/20220714170458.49727-1-sj@kernel.org
Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/vm: only run 128TBswitch with 5-level paging

The test va_128TBswitch.c expects to be able to pass mmap an address hint
and length that cross the address 1<<47.  On x86_64, this is not possible
without 5-level page tables, so the test fails.

The test is already only run on 64-bit powerpc and x86_64 archs, but this
patch adds an additional check on x86_64 that skips the test if
PG_TABLE_LEVELS < 5.  There is precedent for checking /proc/config.gz in
selftests, e.g.  in selftests/firmware.

Running the tests produces the desired output:

sudo make -C tools/testing/selftests TARGETS=vm run_tests
---------------------------
running ./va_128TBswitch.sh
---------------------------
./va_128TBswitch.sh: PG_TABLE_LEVELS=4, must be >= 5 to run this test
[SKIP]
-------------------------------

[adam@wowsignal.io: restrict the check to x86_64]
Link: https://lkml.kernel.org/r/20220628163654.337600-1-adam@wowsignal.io
[adam@wowsignal.io: fix formatting issues, rename "die" to "fail"]
Link: https://lkml.kernel.org/r/20220701163030.415735-1-adam@wowsignal.io
Link: https://lkml.kernel.org/r/20220627163912.5581-1-adam@wowsignal.io
Signed-off-by: Adam Sindelar <adam@wowsignal.io>
Cc: Adam Sindelar <ats@fb.com>
Cc: David Vernet <void@manifault.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: try to free transhuge swapcache when possible

Transhuge swapcaches won't be freed in __collapse_huge_page_copy().  It's
because release_pte_page() is not called for these pages and thus
free_page_and_swap_cache can't grab the page lock.  These pages won't be
freed from swap cache even if we are the only user until next time
reclaim.  It shouldn't hurt indeed, but we could try to free these pages
to save more memory for system.

Link: https://lkml.kernel.org/r/20220625092816.4856-8-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: remove unneeded return value of khugepaged_add_pte_mapped_thp()

The return value of khugepaged_add_pte_mapped_thp() is always 0 and also
ignored.  Remove it to clean up the code.

Link: https://lkml.kernel.org/r/20220625092816.4856-7-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: use helper macro __ATTR_RW

Use helper macro __ATTR_RW to define the khugepaged attributes.  Minor
readability improvement.

Link: https://lkml.kernel.org/r/20220625092816.4856-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: minor cleanup for collapse_file

nr_none is always 0 for non-shmem case because the page can be read from
the backend store.  So when nr_none !  = 0, it must be in is_shmem case.
Also only adjust the nrpages and uncharge shmem when nr_none != 0 to save
cpu cycles.

Link: https://lkml.kernel.org/r/20220625092816.4856-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: trivial typo and codestyle cleanup

Fix some typos and tweak the code to meet codestyle.  No functional change
intended.

Link: https://lkml.kernel.org/r/20220625092816.4856-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: stop swapping in page when VM_FAULT_RETRY occurs

When do_swap_page returns VM_FAULT_RETRY, we do not retry here and thus
swap entry will remain in pagetable.  This will result in later failure.
So stop swapping in pages in this case to save cpu cycles.  As A further
optimization, mmap_lock is released when __collapse_huge_page_swapin()
fails to avoid relocking mmap_lock.  And "swapped_in++" is moved after
error handling to make it more accurate.

Link: https://lkml.kernel.org/r/20220625092816.4856-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: remove unneeded shmem_huge_enabled() check

Patch series "A few cleanup patches for khugepaged", v2.

This series contains a few cleaup patches to remove unneeded return value,
use helper macro, fix typos and so on.  More details can be found in the
respective changelogs.

This patch (of 7):

If we reach here, khugepaged_scan_mm_slot() has already made sure that
hugepage is enabled for shmem, via its call to hugepage_vma_check().
Remove this duplicated check.

Link: https://lkml.kernel.org/r/20220625092816.4856-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220625092816.4856-2-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: sparsemem: drop unexpected word 'a' in comments

there is an unexpected word 'a' in the comments that need to be dropped

Link: https://lkml.kernel.org/r/24fbdae3.c86.1819a0f31b9.Coremail.chenxuebing@jari.cn
Signed-off-by: XueBing Chen <chenxuebing@jari.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb: kill set_huge_swap_pte_at()

Commit e5251fd43007 ("mm/hugetlb: introduce set_huge_swap_pte_at()
helper") add set_huge_swap_pte_at() to handle swap entries on
architectures that support hugepages consisting of contiguous ptes.  And
currently the set_huge_swap_pte_at() is only overridden by arm64.

set_huge_swap_pte_at() provide a sz parameter to help determine the number
of entries to be updated.  But in fact, all hugetlb swap entries contain
pfn information, so we can find the corresponding folio through the pfn
recorded in the swap entry, then the folio_size() is the number of entries
that need to be updated.

And considering that users will easily cause bugs by ignoring the
difference between set_huge_swap_pte_at() and set_huge_pte_at().  Let's
handle swap entries in set_huge_pte_at() and remove the
set_huge_swap_pte_at(), then we can call set_huge_pte_at() anywhere, which
simplifies our coding.

Link: https://lkml.kernel.org/r/20220626145717.53572-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc: make the annotations of available memory more accurate

Not all systems use swap, so estimating available memory would help to
prevent swapping or OOM of system that not use swap.

And we need to reserve some page cache to prevent swapping or thrashing.
If somebody is accessing the pages in pagecache, and if too much would be
freed, most accesses might mean reading data from disk, i.e.  thrashing.

Link: https://lkml.kernel.org/r/20220623020833.972979-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zram: do not lookup algorithm in backends table

Always use crypto_has_comp() so that crypto can lookup module, call
usermodhelper to load the modules, wait for usermodhelper to finish and so
on.  Otherwise crypto will do all of these steps under CPU hot-plug lock
and this looks like too much stuff to handle under the CPU hot-plug lock.
Besides this can end up in a deadlock when usermodhelper triggers a code
path that attempts to lock the CPU hot-plug lock, that zram already holds.

An example of such deadlock:

- path A. zram grabs CPU hot-plug lock, execs /sbin/modprobe from crypto
  and waits for modprobe to finish

disksize_store
 zcomp_create
  __cpuhp_state_add_instance
   __cpuhp_state_add_instance_cpuslocked
    zcomp_cpu_up_prepare
     crypto_alloc_base
      crypto_alg_mod_lookup
       call_usermodehelper_exec
        wait_for_completion_killable
         do_wait_for_common
          schedule

- path B. async work kthread that brings in scsi device. It wants to
  register CPUHP states at some point, and it needs the CPU hot-plug
  lock for that, which is owned by zram.

async_run_entry_fn
 scsi_probe_and_add_lun
  scsi_mq_alloc_queue
   blk_mq_init_queue
    blk_mq_init_allocated_queue
     blk_mq_realloc_hw_ctxs
      __cpuhp_state_add_instance
       __cpuhp_state_add_instance_cpuslocked
        mutex_lock
         schedule

- path C. modprobe sleeps, waiting for all aync works to finish.

load_module
 do_init_module
  async_synchronize_full
   async_synchronize_cookie_domain
    schedule

[senozhatsky@chromium.org: add comment]
Link: https://lkml.kernel.org/r/20220624060606.1014474-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20220622023501.517125-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm, docs: fix comments that mention mem_hotplug_end()

Comments that mention mem_hotplug_end() are confusing as there is no
function called mem_hotplug_end().  Fix them by replacing all the
occurences of mem_hotplug_end() in the comments with mem_hotplug_done().

[akpm@linux-foundation.org: grammatical fixes]
Link: https://lkml.kernel.org/r/20220620071516.1286101-1-p76091292@gs.ncku.edu.tw
Signed-off-by: Yun-Ze Li <p76091292@gs.ncku.edu.tw>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/smaps: add Pss_Dirty

Pss is the sum of the sizes of clean and dirty private pages, and the
proportional sizes of clean and dirty shared pages:

 Private = Private_Dirty + Private_Clean
 Shared_Proportional = Shared_Dirty_Proportional + Shared_Clean_Proportional
 Pss = Private + Shared_Proportional

The Shared*Proportional fields are not present in smaps, so it is not
always possible to determine how much of the Pss is from dirty pages and
how much is from clean pages.  This information can be useful for
measuring memory usage for the purpose of optimisation, since clean pages
can usually be discarded by the kernel immediately while dirty pages
cannot.

The smaps routines in the kernel already have access to this data, so add
a Pss_Dirty to show it to userspace.  Pss_Clean is not added since it can
be calculated from Pss and Pss_Dirty.

Link: https://lkml.kernel.org/r/20220620081251.2928103-1-vincent.whitchurch@axis.com
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: rmap: simplify the hugetlb handling when unmapping or migration

According to previous discussion [1], there are so many levels of
indenting to handle the hugetlb case when unmapping or migration.  We can
combine folio_test_anon() and huge_pmd_unshare() to save one level of
indenting, by adding a local variable and moving the VM_BUG_ON() a little
forward.

No intended functional changes in this patch.

[1] https://lore.kernel.org/all/0b986dc4-5843-3e2d-c2df-5a2e9f13e6ab@oracle.com/

Link: https://lkml.kernel.org/r/28414b1b96f095e838c1e548074f8e0fc70d78cf.1655724713.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/madvise: minor cleanup for swapin_walk_pmd_entry()

Passing index to pte_offset_map_lock() directly so the below calculation
can be avoided. Rename orig_pte to ptep as it's not changed. Also use
helper is_swap_pte() to improve the readability. No functional change
intended.

[akpm@linux-foundation.org: reduce scope of `ptep']
Link: https://lkml.kernel.org/r/20220618090527.37843-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb: remove minimum_order variable

commit 641844f5616d ("mm/hugetlb: introduce minimum hugepage order") fixed
a static checker warning and introduced a global variable minimum_order to
fix the warning.  However, the local variable in
dissolve_free_huge_pages() can be initialized to
huge_page_order(&default_hstate) to fix the warning.

So remove minimum_order to simplify the code.

Link: https://lkml.kernel.org/r/20220616033846.96937-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory_hotplug: make hugetlb_optimize_vmemmap compatible with memmap_on_memory

For now, the feature of hugetlb_free_vmemmap is not compatible with the
feature of memory_hotplug.memmap_on_memory, and hugetlb_free_vmemmap takes
precedence over memory_hotplug.memmap_on_memory.  However, someone wants
to make memory_hotplug.memmap_on_memory takes precedence over
hugetlb_free_vmemmap since memmap_on_memory makes it more likely to
succeed memory hotplug in close-to-OOM situations.  So the decision of
making hugetlb_free_vmemmap take precedence is not wise and elegant.

The proper approach is to have hugetlb_vmemmap.c do the check whether the
section which the HugeTLB pages belong to can be optimized.  If the
section's vmemmap pages are allocated from the added memory block itself,
hugetlb_free_vmemmap should refuse to optimize the vmemmap, otherwise, do
the optimization.  Then both kernel parameters are compatible.  So this
patch introduces VmemmapSelfHosted to mask any non-optimizable vmemmap
pages.  The hugetlb_vmemmap can use this flag to detect if a vmemmap page
can be optimized.

[songmuchun@bytedance.com: walk vmemmap page tables to avoid false-positive]
Link: https://lkml.kernel.org/r/20220620110616.12056-3-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20220617135650.74901-3-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Co-developed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory_hotplug: enumerate all supported section flags

Patch series "make hugetlb_optimize_vmemmap compatible with
memmap_on_memory", v3.

This series makes hugetlb_optimize_vmemmap compatible with
memmap_on_memory.

This patch (of 2):

We are almost running out of section flags, only one bit is available in
the worst case (powerpc with 256k pages).  However, there are still some
free bits (in ->section_mem_map) on other architectures (e.g.  x86_64 has
10 bits available, arm64 has 8 bits available with worst case of 64K
pages).  We have hard coded those numbers in code, it is inconvenient to
use those bits on other architectures except powerpc.  So transfer those
section flags to enumeration to make it easy to add new section flags in
the future.  Also, move SECTION_TAINT_ZONE_DEVICE into the scope of
CONFIG_ZONE_DEVICE to save a bit on non-zone-device case.

[songmuchun@bytedance.com: replace enum with defines per David]
Link: https://lkml.kernel.org/r/20220620110616.12056-2-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20220617135650.74901-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20220617135650.74901-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert __delete_from_swap_cache() to a folio

All callers now have a folio, so convert the entire function to operate
on folios.

Link: https://lkml.kernel.org/r/20220617175020.717127-23-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert delete_from_swap_cache() to take a folio

All but one caller already has a folio, so convert it to use a folio.

Link: https://lkml.kernel.org/r/20220617175020.717127-22-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert page_swap_flags to folio_swap_flags

The only caller already has a folio, so push the folio->page conversion
down a level.

Link: https://lkml.kernel.org/r/20220617175020.717127-21-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert destroy_compound_page() to destroy_large_folio()

All callers now have a folio, so push the folio->page conversion
down to this function.

[akpm@linux-foundation.org: uninline destroy_large_folio() to fix build issue]
Link: https://lkml.kernel.org/r/20220617175020.717127-20-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert __page_cache_release() to use a folio

All the callers now have a folio.  Saves several calls to compound_head,
totalling 502 bytes of text.

Link: https://lkml.kernel.org/r/20220617175020.717127-19-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert __put_compound_page() to __folio_put_large()

All the callers now have a folio, so pass it in.  This doesn't
save any text, but it does save a call to compound_head() as
folio_test_hugetlb() does not contain a call like PageHuge() does.

Link: https://lkml.kernel.org/r/20220617175020.717127-18-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert __put_single_page() to __folio_put_small()

Saves 56 bytes of text by removing a call to compound_head().

Link: https://lkml.kernel.org/r/20220617175020.717127-17-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert __put_page() to __folio_put()

Saves 11 bytes of text by removing a check of PageTail.

Link: https://lkml.kernel.org/r/20220617175020.717127-16-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert put_pages_list to use folios

Pages linked through the LRU list cannot be tail pages as ->compound_head
is in a union with one of the words of the list_head, and they cannot
be ZONE_DEVICE pages as ->pgmap is in a union with the same word.
Saves 60 bytes of text by removing a call to page_is_fake_head().

Link: https://lkml.kernel.org/r/20220617175020.717127-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert release_pages to use a folio internally

This function was already calling compound_head(), but now it can
cache the result of calling compound_head() and avoid calling it again.
Saves 299 bytes of text by avoiding various calls to compound_page()
and avoiding checks of PageTail.

Link: https://lkml.kernel.org/r/20220617175020.717127-14-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert try_to_free_swap to use a folio

Save a few calls to compound_head by converting the passed page to
a folio.  Reduces kernel text size by 74 bytes.

Link: https://lkml.kernel.org/r/20220617175020.717127-13-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: optimise lru_add_drain_cpu()

Do the per-cpu dereferencing of the fbatches once which saves 14 bytes
of text and several percpu relocations.

Link: https://lkml.kernel.org/r/20220617175020.717127-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: pull the CPU conditional out of __lru_add_drain_all()

The function is too long, so pull this complicated conditional out into
cpu_needs_drain().  This ends up shrinking the text by 14 bytes,
by allowing GCC to cache the result of calling per_cpu() instead of
relocating each lookup individually.

Link: https://lkml.kernel.org/r/20220617175020.717127-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: rename lru_pvecs to cpu_fbatches

No change to generated code, but this struct no longer contains any
pagevecs, and not all the folio batches it contains are lru.

Link: https://lkml.kernel.org/r/20220617175020.717127-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert activate_page to a folio_batch

Rename it to just 'activate', saving 696 bytes of text from removals
of compound_page() and the pagevec_lru_move_fn() infrastructure.
Inline need_activate_page_drain() into its only caller.

Link: https://lkml.kernel.org/r/20220617175020.717127-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert lru_lazyfree to a folio_batch

Using folios instead of pages removes several calls to compound_head(),
shrinking the kernel by 1089 bytes of text.

Link: https://lkml.kernel.org/r/20220617175020.717127-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert lru_deactivate to a folio_batch

Using folios instead of pages shrinks deactivate_page() and
lru_deactivate_fn() by 778 bytes between them.

Link: https://lkml.kernel.org/r/20220617175020.717127-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert lru_deactivate_file to a folio_batch

Use a folio throughout lru_deactivate_file_fn(), removing many hidden
calls to compound_head().  Shrinks the kernel by 864 bytes of text.

Link: https://lkml.kernel.org/r/20220617175020.717127-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: convert lru_add to a folio_batch

When adding folios to the LRU for the first time, the LRU flag will
already be clear, so skip the test-and-clear part of moving from one
LRU to another.

Removes 285 bytes from kernel text, mostly due to removing
__pagevec_lru_add().

Link: https://lkml.kernel.org/r/20220617175020.717127-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: make __pagevec_lru_add static

__pagevec_lru_add has no callers outside swap.c, so make it static,
and move it to a more logical position in the file.

Link: https://lkml.kernel.org/r/20220617175020.717127-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: add folio_batch_move_lru()

Start converting the LRU from pagevecs to folio_batches.

Combine the functionality of pagevec_add_and_need_flush() with
pagevec_lru_move_fn() in the new folio_batch_add_and_move().

Convert the lru_rotate pagevec to a folio_batch.

Adds 223 bytes total to kernel text, because we're duplicating
infrastructure.  This will be more than made up for in future patches.

Link: https://lkml.kernel.org/r/20220617175020.717127-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: add folios_put()

Patch series "Convert the swap code to be more folio-based".

There's still more to do with the swap code, but this reaps a lot of the
folio benefit.  More than 4kB of kernel text saved (with the UEK7 kernel
config).  I don't know how much that's going to translate into CPU
savings, but some of those compound_head() calls are on every page free,
so it should be noticable.  It might even be noticable just from an
I-cache consumption perspective.

This patch (of 22):

This is just a wrapper around release_pages() for now.  Place the
prototype in mm.h along with folio_put() and folio_put_refs().

Link: https://lkml.kernel.org/r/20220617175020.717127-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20220617175020.717127-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: convert reclaim_pages() to use a folio

Remove a few hidden calls to compound_head, saving 76 bytes of text.

Link: https://lkml.kernel.org/r/20220617154248.700416-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: convert shrink_active_list() to use a folio

Remove a few hidden calls to compound_head, saving 411 bytes of text.

Link: https://lkml.kernel.org/r/20220617154248.700416-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: convert move_pages_to_lru() to use a folio

Remove a few hidden calls to compound_head, saving 387 bytes of text on
my test configuration.

Link: https://lkml.kernel.org/r/20220617154248.700416-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: convert isolate_lru_pages() to use a folio

Remove a few hidden calls to compound_head, saving 279 bytes of text.

Link: https://lkml.kernel.org/r/20220617154248.700416-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: convert reclaim_clean_pages_from_list() to folios

Patch series "nvert much of vmscan to folios"

vmscan always operates on folios since it puts the pages on the LRU list.
Switching all of these functions from pages to folios saves 1483 bytes of
text from removing all the baggage around calling compound_page() and
similar functions.

This patch (of 5):

This is a straightforward conversion which removes several hidden calls
to compound_head, saving 330 bytes of kernel text.

Link: https://lkml.kernel.org/r/20220617154248.700416-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20220617154248.700416-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mprotect: try avoiding write faults for exclusive anonymous pages when changing protection

Similar to our MM_CP_DIRTY_ACCT handling for shared, writable mappings, we
can try mapping anonymous pages in a private writable mapping writable if
they are exclusive, the PTE is already dirty, and no special handling
applies.  Mapping the anonymous page writable is essentially the same
thing the write fault handler would do in this case.

Special handling is required for uffd-wp and softdirty tracking, so take
care of that properly.  Also, leave PROT_NONE handling alone for now; in
the future, we could similarly extend the logic in do_numa_page() or use
pte_mk_savedwrite() here.

While this improves mprotect(PROT_READ)+mprotect(PROT_READ|PROT_WRITE)
performance, it should also be a valuable optimization for uffd-wp, when
un-protecting.

This has been previously suggested by Peter Collingbourne in [1], relevant
in the context of the Scudo memory allocator, before we had
PageAnonExclusive.

This commit doesn't add the same handling for PMDs (i.e., anonymous THP,
anonymous hugetlb); benchmark results from Andrea indicate that there are
minor performance gains, so it's might still be valuable to streamline
that logic for all anonymous pages in the future.

As we now also set MM_CP_DIRTY_ACCT for private mappings, let's rename it
to MM_CP_TRY_CHANGE_WRITABLE, to make it clearer what's actually
happening.

Micro-benchmark courtesy of Andrea:

===
 #define _GNU_SOURCE
 #include <sys/mman.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>

 #define SIZE (1024*1024*1024)

int main(int argc, char *argv[])
{
char *p;
if (posix_memalign((void **)&p, sysconf(_SC_PAGESIZE)*512, SIZE))
perror("posix_memalign"), exit(1);
if (madvise(p, SIZE, argc > 1 ? MADV_HUGEPAGE : MADV_NOHUGEPAGE))
perror("madvise");
explicit_bzero(p, SIZE);
for (int loops = 0; loops < 40; loops++) {
if (mprotect(p, SIZE, PROT_READ))
perror("mprotect"), exit(1);
if (mprotect(p, SIZE, PROT_READ|PROT_WRITE))
perror("mprotect"), exit(1);
explicit_bzero(p, SIZE);
}
}
===

Results on my Ryzen 9 3900X:

Stock 10 runs (lower is better):   AVG 6.398s, STDEV 0.043
Patched 10 runs (lower is better): AVG 3.780s, STDEV 0.026

===

[1] https://lkml.kernel.org/r/20210429214801.2583336-1-pcc@google.com

Link: https://lkml.kernel.org/r/20220614093629.76309-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Peter Collingbourne <pcc@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

userfaultfd: selftests: infinite loop in faulting_process

On Android this test is getting stuck in an infinite loop due to
indeterminate behavior:

The local variables steps and signalled were being reset to 1 and 0
respectively after every jump back to sigsetjmp by siglongjmp in the
signal handler.  The test was incrementing them and expecting them to
retain their incremented values.  The documentation for siglongjmp says:

All accessible objects have values as of the time sigsetjmp() was called,
except that the values of objects of automatic storage duration which are
local to the function containing the invocation of the corresponding
sigsetjmp() which do not have volatile-qualified type and which are
changed between the sigsetjmp() invocation and siglongjmp() call are
indeterminate.

Tagging steps and signalled with volatile enabled the test to pass.

Link: https://lkml.kernel.org/r/20220613233321.431282-1-edliaw@google.com
Signed-off-by: Edward Liaw <edliaw@google.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Docs/admin-guide/damon: add a document for DAMON_LRU_SORT

This commit documents the usage of DAMON_LRU_SORT for admins.

Link: https://lkml.kernel.org/r/20220613192301.8817-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon: introduce DAMON-based LRU-lists Sorting

Users can do data access-aware LRU-lists sorting using 'LRU_PRIO' and
'LRU_DEPRIO' DAMOS actions.  However, finding best parameters including
the hotness/coldness thresholds, CPU quota, and watermarks could be
challenging for some users.  To make the scheme easy to be used without
complex tuning for common situations, this commit implements a static
kernel module called 'DAMON_LRU_SORT' using the 'LRU_PRIO' and
'LRU_DEPRIO' DAMOS actions.

It proactively sorts LRU-lists using DAMON with conservatively chosen
default values of the parameters.  That is, the module under its default
parameters will make no harm for common situations but provide some level
of efficiency improvements for systems having clear hot/cold access
pattern under a level of memory pressure while consuming only a limited
small portion of CPU time.

Link: https://lkml.kernel.org/r/20220613192301.8817-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Docs/admin-guide/damon/sysfs: document 'LRU_DEPRIO' scheme action

This commit documents the 'LRU_DEPRIO' scheme action for DAMON sysfs
interface.`

Link: https://lkml.kernel.org/r/20220613192301.8817-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/schemes: add 'LRU_DEPRIO' action

This commit adds a new DAMON-based operation scheme action called
'LRU_DEPRIO' for physical address space.  The action deprioritizes pages
in the memory area of the target access pattern on their LRU lists.  This
is hence supposed to be used for rarely accessed (cold) memory regions so
that cold pages could be more likely reclaimed first under memory
pressure.  Internally, it simply calls 'lru_deactivate()'.

Using this with 'LRU_PRIO' action for hot pages, users can proactively
sort LRU lists based on the access pattern.  That is, it can make the LRU
lists somewhat more trustworthy source of access temperature.  As a
result, efficiency of LRU-lists based mechanisms including the reclamation
target selection could be improved.

Link: https://lkml.kernel.org/r/20220613192301.8817-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Docs/admin-guide/damon/sysfs: document 'LRU_PRIO' scheme action

This commit documents the 'lru_prio' scheme action for DAMON sysfs
interface.

Link: https://lkml.kernel.org/r/20220613192301.8817-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/schemes: add 'LRU_PRIO' DAMOS action

This commit adds a new DAMOS action called 'LRU_PRIO' for the physical
address space.  The action prioritizes pages in the memory regions of the
user-specified target access pattern on their LRU lists.  This is hence
supposed to be used for frequently accessed (hot) memory regions so that
hot pages could be more likely protected under memory pressure.
Internally, it simply calls 'mark_page_accessed()'.

Link: https://lkml.kernel.org/r/20220613192301.8817-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/paddr: use a separate function for 'DAMOS_PAGEOUT' handling

This commit moves code for 'DAMOS_PAGEOUT' handling of the physical
address space monitoring operations set to a separate function so that its
caller, 'damon_pa_apply_scheme()', can be more easily extended for
additional DAMOS actions later.

Link: https://lkml.kernel.org/r/20220613192301.8817-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/dbgfs: add and use mappings between 'schemes' action inputs and 'damos_action' values

Patch series "Extend DAMOS for Proactive LRU-lists Sorting".

Introduction
============

In short, this patchset 1) extends DAMON-based Operation Schemes (DAMOS)
for low overhead data access pattern based LRU-lists sorting, and 2)
implements a static kernel module for easy use of conservatively-tuned
version of that using the extended DAMOS capability.

Background
----------

As page-granularity access checking overhead could be significant on huge
systems, LRU lists are normally not proactively sorted but partially and
reactively sorted for special events including specific user requests,
system calls and memory pressure.  As a result, LRU lists are sometimes
not so perfectly prepared to be used as a trustworthy access pattern
source for some situations including reclamation target pages selection
under sudden memory pressure.

DAMON-based Proactive LRU-lists Sorting
---------------------------------------

Because DAMON can identify access patterns of best-effort accuracy while
inducing only user-specified range of overhead, using DAMON for Proactive
LRU-lists Sorting (PLRUS) could be helpful for this situation.  The idea
is quite simple.  Find hot pages and cold pages using DAMON, and
prioritize hot pages while deprioritizing cold pages on their LRU-lists.

This patchset extends DAMON to support such schemes by introducing a
couple of new DAMOS actions for prioritizing and deprioritizing memory
regions of specific access patterns on their LRU-lists.  In detail, this
patchset simply uses 'mark_page_accessed()' and 'deactivate_page()'
functions for prioritization and deprioritization of pages on their LRU
lists, respectively.

To make the scheme easy to use without complex tuning for common
situations, this patchset further implements a static kernel module called
'DAMON_LRU_SORT' using the extended DAMOS functionality.  It proactively
sorts LRU-lists using DAMON with conservatively chosen default
hotness/coldness thresholds and small CPU usage quota limit.  That is, the
module under its default parameters will make no harm for common situation
but provide some level of benefit for systems having clear hot/cold access
pattern under only memory pressure while consuming only limited small
portion of CPU time.

Related Works
-------------

Proactive reclamation is well known to be helpful for reducing non-optimal
reclamation target selection caused performance drops.  However, proactive
reclamation is not a best option for some cases, because it could incur
additional I/O.  For an example, it could be prohitive for systems using
storage devices that total number of writes is limited, or cloud block
storages that charges every I/O.

Some proactive reclamation approaches[1,2] induce a level of memory
pressure using memcg files or swappiness while monitoring PSI.  As
reclamation target selection is still relying on the original LRU-lists
mechanism, using DAMON-based proactive reclamation before inducing the
proactive reclamation could allow more memory saving with same level of
performance overhead, or less performance overhead with same level of
memory saving.

[1] https://blogs.oracle.com/linux/post/anticipating-your-memory-needs
[2] https://www.pdl.cmu.edu/ftp/NVM/tmo_asplos22.pdf

Evaluation
==========

In short, PLRUS achieves 10% memory PSI (some) reduction, 14% major page
faults reduction, and 3.74% speedup under memory pressure.

Setup
-----

To show the effect of PLRUS, I run PARSEC3 and SPLASH-2X benchmarks under
below variant systems and measure a few metrics including the runtime of
each workload, number of system-wide major page faults, and system-wide
memory PSI (some).

- orig: v5.18-rc4 based mm-unstable kernel + this patchset, but no DAMON scheme
        applied.
- mprs: Same to 'orig' but artificial memory pressure is induced.
- plrus: Same to 'mprs' but a radically tuned PLRUS scheme is applied to the
         entire physical address space of the system.

For the artificial memory pressure, I set 'memory.limit_in_bytes' to 75%
of the running workload's peak RSS, wait 1 second, remove the pressure by
setting it to 200% of the peak RSS, wait 10 seconds, and repeat the
procedure until the workload finishes[1].  I use zram based swap device.
The tests are automated[2].

[1] https://github.com/awslabs/damon-tests/blob/next/perf/runners/back/0009_memcg_pressure.sh
[2] https://github.com/awslabs/damon-tests/blob/next/perf/full_once_config.sh

Radically Tuned PLRUS
---------------------

To show effect of PLRUS on the PARSEC3/SPLASH-2X workloads which runs for
no long time, we use radically tuned version of PLRUS.  The version asks
DAMON to do the proactive LRU-lists sorting as below.

1. Find any memory regions shown some accesses (approximately >=20 accesses per
   100 sampling) and prioritize pages of the regions on their LRU lists using
   up to 2% CPU time.  Under the CPU time limit, prioritize regions having
   higher access frequency and kept the access frequency longer first.

2. Find any memory regions shown no access for at least >=5 seconds and
   deprioritize pages of the rgions on their LRU lists using up to 2% CPU time.
   Under the CPU time limit, deprioritize regions that not accessed for longer
   time first.

Results
-------

I repeat the tests 25 times and calculate average of the measured numbers.
The results are as below:

    metric               orig        mprs         plrus        plrus/mprs
    runtime_seconds      190.06      292.83       281.87       0.96
    pgmajfaults          852.55      8769420.00   7525040.00   0.86
    memory_psi_some_us   106911.00   6943420.00   6220920.00   0.90

The first row is for legend.  The first cell shows the metric that the
following cells of the row shows.  Second, third, and fourth cells show
the metrics under the configs shown at the first row of the cell, and the
fifth cell shows the metric under 'plrus' divided by the metric under
'mprs'.  Second row shows the averaged runtime of the workloads in
seconds.  Third row shows the number of system-wide major page faults
while the test was ongoing.  Fourth row shows the system-wide memory
pressure stall for some processes in microseconds while the test was
ongoing.

In short, PLRUS achieves 10% memory PSI (some) reduction, 14% major page
faults reduction, and 3.74% speedup under memory pressure.  We also
confirmed the CPU usage of kdamond was 2.61% of single CPU, which is below
4% as expected.

Sequence of Patches
===================

The first and second patch cleans up DAMON debugfs interface and
DAMOS_PAGEOUT handling code of physical address space monitoring
operations implementation for easier extension of the code.

The thrid and fourth patches implement a new DAMOS action called
'lru_prio', which prioritizes pages under memory regions which have a
user-specified access pattern, and document it, respectively.  The fifth
and sixth patches implement yet another new DAMOS action called
'lru_deprio', which deprioritizes pages under memory regions which have a
user-specified access pattern, and document it, respectively.

The seventh patch implements a static kernel module called
'damon_lru_sort', which utilizes the DAMON-based proactive LRU-lists
sorting under conservatively chosen default parameter.  Finally, the
eighth patch documents 'damon_lru_sort'.

This patch (of 8):

DAMON debugfs interface assumes users will write 'damos_action' value
directly to the 'schemes' file.  This makes adding new 'damos_action' in
the middle of its definition breaks the backward compatibility of DAMON
debugfs interface, as values of some 'damos_action' could be changed.  To
mitigate the situation, this commit adds mappings between the user inputs
and 'damos_action' value and makes DAMON debugfs code uses those.

Link: https://lkml.kernel.org/r/20220613192301.8817-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20220613192301.8817-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swap: remove swap_cache_info statistics

swap_cache_info are not statistics that could be easily used to tune
system performance because they are not easily accessile.  Also they can't
provide really useful info when OOM occurs.  Remove these statistics can
also help mitigate unneeded global swap_cache_info cacheline contention.

Link: https://lkml.kernel.org/r/20220608144031.829-4-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/swapfile: fix possible data races of inuse_pages

si->inuse_pages could still be accessed concurrently now.  The plain reads
outside si->lock critical section, i.e.  swap_show and si_swapinfo, which
results in data races.  READ_ONCE and WRITE_ONCE is used to fix such data
races.  Note these data races should be ok because they're just used for
showing swap info.

[linmiaohe@huawei.com: use WRITE_ONCE to pair with READ_ONCE]
Link: https://lkml.kernel.org/r/20220625093346.48894-2-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220608144031.829-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/test_vmalloc: switch to prandom_u32()

A get_random_bytes() function can cause a high contention if it is called
across CPUs simultaneously.  Because it shares one lock per all CPUs:

<snip>
   class name     con-bounces  contentions   waittime-min   waittime-max waittime-total   waittime-avg    acq-bounces   acquisitions   holdtime-min   holdtime-max holdtime-total   holdtime-avg
   &crng->lock:   663145       665886        0.05           8.85         261966.66        0.39            7188152       13731279       0.04           11.89        2181582.30       0.16
   -----------
   &crng->lock    307835       [<00000000acba59cd>] _extract_crng+0x48/0x90
   &crng->lock    358051       [<00000000f0075abc>] _crng_backtrack_protect+0x32/0x90
   -----------
   &crng->lock    234241       [<00000000f0075abc>] _crng_backtrack_protect+0x32/0x90
   &crng->lock    431645       [<00000000acba59cd>] _extract_crng+0x48/0x90
<snip>

Switch from the get_random_bytes() to prandom_u32() that does not have any
internal contention when a random value is needed for the tests.

The reason is to minimize CPU cycles introduced by the test-suite itself
from the vmalloc performance metrics.

Link: https://lkml.kernel.org/r/20220607093449.3100-6-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc: extend __find_vmap_area() with one more argument

__find_vmap_area() finds a "vmap_area" based on passed address.  It scan
the specific "vmap_area_root" rb-tree.  Extend the function with one extra
argument, so any tree can be specified where the search has to be done.

There is no functional change as a result of this patch.

Link: https://lkml.kernel.org/r/20220607093449.3100-5-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc: initialize VA's list node after unlink

A vmap_area can travel between different places.  For example
attached/detached to/from different rb-trees.  In order to prevent fancy
bugs, initialize a VA's list node after it is removed from the list, so it
pairs with VA's rb_node which is also initialized.

There is no functional change as a result of this patch.

Link: https://lkml.kernel.org/r/20220607093449.3100-4-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc: extend __alloc_vmap_area() with extra arguments

It implies that __alloc_vmap_area() allocates only from the global vmap
space, therefore a list-head and rb-tree, which represent a free vmap
space, are not passed as parameters to this function and are accessed
directly from this function.

Extend the __alloc_vmap_area() and other dependent functions to have a
possibility to allocate from different trees making an interface common
and not specific.

There is no functional change as a result of this patch.

Link: https://lkml.kernel.org/r/20220607093449.3100-3-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc: make link_va()/unlink_va() common to different rb_root

Patch series "Reduce a vmalloc internal lock contention preparation work".

This small serias is preparation work to implement per-cpu vmalloc
allocation in order to reduce a high internal lock contention.  This
series does not introduce any functional changes, it is only about
preparation.

This patch (of 5):

Currently link_va() and unlik_va(), in order to figure out a tree type,
compares a passed root value with a global free_vmap_area_root variable to
distinguish the augmented rb-tree from a regular one.  It is hard coded
since such functions can manipulate only with specific
"free_vmap_area_root" tree that represents a global free vmap space.

Make it common by introducing "_augment" versions of both internal
functions, so it is possible to deal with different trees.

There is no functional change as a result of this patch.

Link: https://lkml.kernel.org/r/20220607093449.3100-1-urezki@gmail.com
Link: https://lkml.kernel.org/r/20220607093449.3100-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sony.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: shrinkers: add scan interface for shrinker debugfs

Add a scan interface which allows to trigger scanning of a particular
shrinker and specify memcg and numa node.  It's useful for testing,
debugging and profiling of a specific scan_objects() callback.  Unlike
alternatives (creating a real memory pressure and dropping caches via
/proc/sys/vm/drop_caches) this interface allows to interact with only one
shrinker at once.  Also, if a shrinker is misreporting the number of
objects (as some do), it doesn't affect scanning.

[roman.gushchin@linux.dev: improve typing, fix arg count checking]
Link: https://lkml.kernel.org/r/YpgKttTowT22mKPQ@carbon
[akpm@linux-foundation.org: fix arg count checking]
Link: https://lkml.kernel.org/r/20220601032227.4076670-7-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools: add memcg_shrinker.py

Add a simple tool which prints a sorted list of shrinker lists in the
following format: (number of objects, shrinker name, cgroup).

Example:
  $ ./memcg_shrinker.py -n 10
  2090     sb-sysfs-26          /sys/fs/cgroup/system.slice
  1809     sb-sysfs-26          /sys/fs/cgroup/system.slice/systemd-udevd.service
  1044     sb-btrfs:vda2-24     /sys/fs/cgroup/system.slice/system-dbus\x2d:1.3\...
  861      sb-btrfs:vda2-24     /sys/fs/cgroup/system.slice/system-dbus\x2d:1.3\...
  804      sb-btrfs:vda2-24     /sys/fs/cgroup/system.slice
  643      sb-btrfs:vda2-24     /sys/fs/cgroup/system.slice/firewalld.service
  616      sb-cgroup2-30        /sys/fs/cgroup/init.scope
  275      sb-sysfs-26          /
  238      sb-proc-25           /sys/fs/cgroup/system.slice/systemd-journald.service
  225      sb-proc-25           /sys/fs/cgroup/system.slice/abrtd.service

Link: https://lkml.kernel.org/r/20220601032227.4076670-6-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: docs: document shrinker debugfs

Add a document describing the shrinker debugfs interface.

Link: https://lkml.kernel.org/r/20220601032227.4076670-5-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: shrinkers: provide shrinkers with names

Currently shrinkers are anonymous objects.  For debugging purposes they
can be identified by count/scan function names, but it's not always
useful: e.g.  for superblock's shrinkers it's nice to have at least an
idea of to which superblock the shrinker belongs.

This commit adds names to shrinkers.  register_shrinker() and
prealloc_shrinker() functions are extended to take a format and arguments
to master a name.

In some cases it's not possible to determine a good name at the time when
a shrinker is allocated.  For such cases shrinker_debugfs_rename() is
provided.

The expected format is:
    <subsystem>-<shrinker_type>[:<instance>]-<id>
For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair.

After this change the shrinker debugfs directory looks like:
  $ cd /sys/kernel/debug/shrinker/
  $ ls
    dquota-cache-16     sb-devpts-28     sb-proc-47       sb-tmpfs-42
    mm-shadow-18        sb-devtmpfs-5    sb-proc-48       sb-tmpfs-43
    mm-zspool:zram0-34  sb-hugetlbfs-17  sb-pstore-31     sb-tmpfs-44
    rcu-kfree-0         sb-hugetlbfs-33  sb-rootfs-2      sb-tmpfs-49
    sb-aio-20           sb-iomem-12      sb-securityfs-6  sb-tracefs-13
    sb-anon_inodefs-15  sb-mqueue-21     sb-selinuxfs-22  sb-xfs:vda1-36
    sb-bdev-3           sb-nsfs-4        sb-sockfs-8      sb-zsmalloc-19
    sb-bpf-32           sb-pipefs-14     sb-sysfs-26      thp-deferred_split-10
    sb-btrfs:vda2-24    sb-proc-25       sb-tmpfs-1       thp-zero-9
    sb-cgroup2-30       sb-proc-39       sb-tmpfs-27      xfs-buf:vda1-37
    sb-configfs-23      sb-proc-41       sb-tmpfs-29      xfs-inodegc:vda1-38
    sb-dax-11           sb-proc-45       sb-tmpfs-35
    sb-debugfs-7        sb-proc-46       sb-tmpfs-40

[roman.gushchin@linux.dev: fix build warnings]
Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lkml.kernel.org/r/20220601032227.4076670-4-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>