mm/memcontrol: export memcg->watermark via sysfs for v2 memcg

We run a lot of automated tests when building our software and run into
OOM scenarios when the tests run unbounded.  v1 memcg exports
memcg->watermark as "memory.max_usage_in_bytes" in sysfs.  We use this
metric to heuristically limit the number of tests that can run in parallel
based on per test historical data.

This metric is currently not exported for v2 memcg and there is no other
easy way of getting this information.  getrusage() syscall returns
"ru_maxrss" which can be used as an approximation but that's the max RSS
of a single child process across all children instead of the aggregated
max for all child processes.  The only work around is to periodically poll
"memory.current" but that's not practical for short-lived one-off cgroups.

Hence, expose memcg->watermark as "memory.peak" for v2 memcg.

Link: https://lkml.kernel.org/r/20220507050916.GA13577@us192.sjc.aristanetworks.com
Signed-off-by: Ganesan Rajagopal <rganesan@arista.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb_vmemmap: add hugetlb_optimize_vmemmap sysctl

We must add hugetlb_free_vmemmap=on (or "off") to the boot cmdline and
reboot the server to enable or disable the feature of optimizing vmemmap
pages associated with HugeTLB pages.  However, rebooting usually takes a
long time.  So add a sysctl to enable or disable the feature at runtime
without rebooting.  Why we need this?  There are 3 use cases.

1) The feature of minimizing overhead of struct page associated with
   each HugeTLB is disabled by default without passing
   "hugetlb_free_vmemmap=on" to the boot cmdline.  When we (ByteDance)
   deliver the servers to the users who want to enable this feature, they
   have to configure the grub (change boot cmdline) and reboot the
   servers, whereas rebooting usually takes a long time (we have thousands
   of servers).  It's a very bad experience for the users.  So we need a
   approach to enable this feature after rebooting.  This is a use case in
   our practical environment.

2) Some use cases are that HugeTLB pages are allocated 'on the fly'
   instead of being pulled from the HugeTLB pool, those workloads would be
   affected with this feature enabled.  Those workloads could be
   identified by the characteristics of they never explicitly allocating
   huge pages with 'nr_hugepages' but only set 'nr_overcommit_hugepages'
   and then let the pages be allocated from the buddy allocator at fault
   time.  We can confirm it is a real use case from the commit
   099730d67417.  For those workloads, the page fault time could be ~2x
   slower than before.  We suspect those users want to disable this
   feature if the system has enabled this before and they don't think the
   memory savings benefit is enough to make up for the performance drop.

3) If the workload which wants vmemmap pages to be optimized and the
   workload which wants to set 'nr_overcommit_hugepages' and does not want
   the extera overhead at fault time when the overcommitted pages be
   allocated from the buddy allocator are deployed in the same server.
   The user could enable this feature and set 'nr_hugepages' and
   'nr_overcommit_hugepages', then disable the feature.  In this case, the
   overcommited HugeTLB pages will not encounter the extra overhead at
   fault time.

Link: https://lkml.kernel.org/r/20220512041142.39501-5-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb_vmemmap: use kstrtobool for hugetlb_vmemmap param parsing

Use kstrtobool rather than open coding "on" and "off" parsing in
mm/hugetlb_vmemmap.c, which is more powerful to handle all kinds of
parameters like 'Yy1Nn0' or [oO][NnFf] for "on" and "off".

Link: https://lkml.kernel.org/r/20220512041142.39501-4-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on

Optimizing HugeTLB vmemmap pages is not compatible with allocating memmap
on hot added memory.  If "hugetlb_free_vmemmap=on" and
memory_hotplug.memmap_on_memory" are both passed on the kernel command
line, optimizing hugetlb pages takes precedence.  However, the global
variable memmap_on_memory will still be set to 1, even though we will not
try to allocate memmap on hot added memory.

Also introduce mhp_memmap_on_memory() helper to move the definition of
"memmap_on_memory" to the scope of CONFIG_MHP_MEMMAP_ON_MEMORY.  In the
next patch, mhp_memmap_on_memory() will also be exported to be used in
hugetlb_vmemmap.c.

Link: https://lkml.kernel.org/r/20220512041142.39501-3-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: hugetlb_vmemmap: disable hugetlb_optimize_vmemmap when struct page crosses page boundaries

Patch series "add hugetlb_optimize_vmemmap sysctl", v11.

This series aims to add hugetlb_optimize_vmemmap sysctl to enable or
disable the feature of optimizing vmemmap pages associated with HugeTLB
pages.

This patch (of 4):

If the size of "struct page" is not the power of two but with the feature
of minimizing overhead of struct page associated with each HugeTLB is
enabled, then the vmemmap pages of HugeTLB will be corrupted after
remapping (panic is about to happen in theory).  But this only exists when
!CONFIG_MEMCG && !CONFIG_SLUB on x86_64.  However, it is not a
conventional configuration nowadays.  So it is not a real word issue, just
the result of a code review.

But we cannot prevent anyone from configuring that combined configure.
This hugetlb_optimize_vmemmap should be disable in this case to fix this
issue.

Link: https://lkml.kernel.org/r/20220512041142.39501-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20220512041142.39501-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: rmap: fix CONT-PTE/PMD size hugetlb issue when unmapping

On some architectures (like ARM64), it can support CONT-PTE/PMD size
hugetlb, which means it can support not only PMD/PUD size hugetlb: 2M and
1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page size specified.

When unmapping a hugetlb page, we will get the relevant page table entry
by huge_pte_offset() only once to nuke it.  This is correct for PMD or PUD
size hugetlb, since they always contain only one pmd entry or pud entry in
the page table.

However this is incorrect for CONT-PTE and CONT-PMD size hugetlb, since
they can contain several continuous pte or pmd entry with same page table
attributes, so we will nuke only one pte or pmd entry for this
CONT-PTE/PMD size hugetlb page.

And now try_to_unmap() is only passed a hugetlb page in the case where the
hugetlb page is poisoned.  Which means now we will unmap only one pte
entry for a CONT-PTE or CONT-PMD size poisoned hugetlb page, and we can
still access other subpages of a CONT-PTE or CONT-PMD size poisoned
hugetlb page, which will cause serious issues possibly.

So we should change to use huge_ptep_clear_flush() to nuke the hugetlb
page table to fix this issue, which already considered CONT-PTE and
CONT-PMD size hugetlb.

We've already used set_huge_swap_pte_at() to set a poisoned swap entry for
a poisoned hugetlb page.  Meanwhile adding a VM_BUG_ON() to make sure the
passed hugetlb page is poisoned in try_to_unmap().

Link: https://lkml.kernel.org/r/0a2e547238cad5bc153a85c3e9658cb9d55f9cac.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/730ea4b6d292f32fb10b7a4e87dad49b0eb30474.1652147571.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: rmap: fix CONT-PTE/PMD size hugetlb issue when migration

On some architectures (like ARM64), it can support CONT-PTE/PMD size
hugetlb, which means it can support not only PMD/PUD size hugetlb: 2M and
1G, but also CONT-PTE/PMD size: 64K and 32M if a 4K page size specified.

When migrating a hugetlb page, we will get the relevant page table entry
by huge_pte_offset() only once to nuke it and remap it with a migration
pte entry.  This is correct for PMD or PUD size hugetlb, since they always
contain only one pmd entry or pud entry in the page table.

However this is incorrect for CONT-PTE and CONT-PMD size hugetlb, since
they can contain several continuous pte or pmd entry with same page table
attributes.  So we will nuke or remap only one pte or pmd entry for this
CONT-PTE/PMD size hugetlb page, which is not expected for hugetlb
migration.  The problem is we can still continue to modify the subpages'
data of a hugetlb page during migrating a hugetlb page, which can cause a
serious data consistent issue, since we did not nuke the page table entry
and set a migration pte for the subpages of a hugetlb page.

To fix this issue, we should change to use huge_ptep_clear_flush() to nuke
a hugetlb page table, and remap it with set_huge_pte_at() and
set_huge_swap_pte_at() when migrating a hugetlb page, which already
considered the CONT-PTE or CONT-PMD size hugetlb.

[akpm@linux-foundation.org: fix nommu build]
[baolin.wang@linux.alibaba.com: fix build errors for !CONFIG_MMU]
Link: https://lkml.kernel.org/r/a4baca670aca637e7198d9ae4543b8873cb224dc.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/ea5abf529f0997b5430961012bfda6166c1efc8c.1652147571.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: change huge_ptep_clear_flush() to return the original pte

Patch series "Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating", v4.

presently, migrating a hugetlb page or unmapping a poisoned hugetlb page,
we'll use ptep_clear_flush() and set_pte_at() to nuke the page table entry
and remap it, and this is incorrect for CONT-PTE or CONT-PMD size hugetlb
page, which will cause potential data consistent issue.  This patch set
will change to use hugetlb related APIs to fix this issue.

Note: Mike pointed out the huge_ptep_get() will only return the one
specific value, and it would not take into account the dirty or young bits
of CONT-PTE/PMDs like the huge_ptep_get_and_clear() [1].  This
inconsistent issue is not introduced by this patch set, and this issue
will be addressed in another thread [2].  Meanwhile the uffd for hugetlb
case [3] pointed out by Gerald also needs another patch to address.

[1] https://lore.kernel.org/linux-mm/85bd80b4-b4fd-0d3f-a2e5-149559f2f387@oracle.com/
[2] https://lore.kernel.org/all/cover.1651998586.git.baolin.wang@linux.alibaba.com/
[3] https://lore.kernel.org/linux-mm/20220503120343.6264e126@thinkpad/

This patch (of 3):

It is incorrect to use ptep_clear_flush() to nuke a hugetlb page table
when unmapping or migrating a hugetlb page, and will change to use
huge_ptep_clear_flush() instead in the following patches.

So this is a preparation patch, which changes the huge_ptep_clear_flush()
to return the original pte to help to nuke a hugetlb page table.

[baolin.wang@linux.alibaba.com: fix build in several more architectures]
Link: https://lkml.kernel.org/r/0009a4cd-2826-e8be-e671-f050d4f18d5d@linux.alibaba.com
[sfr@canb.auug.org.au: fixup]
Link: https://lkml.kernel.org/r/20220511181531.7f27a5c1@canb.auug.org.au
Link: https://lkml.kernel.org/r/cover.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20f77ddab90baa249bd24504c413189b82acde69.1652270205.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/cover.1652147571.git.baolin.wang@linux.alibaba.com
Link: https://lkml.kernel.org/r/dcf065868cce35bceaf138613ad27f17bb7c0c19.1652147571.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Rich Felker <dalias@libc.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/vm: rework "Temporary Virtual Mappings" section

Extend and rework the "Temporary Virtual Mappings" section of the
highmem.rst documentation.

Despite the local kmaps were introduced by Thomas Gleixner in October
2020, documentation was still missing information about them.  These
additions rely largely on Gleixner's patches, Jonathan Corbet's LWN
articles, comments by Ira Weiny and Matthew Wilcox, and in-code comments
from ./include/linux/highmem.h.

1) Add a paragraph to document kmap_local_page().
2) Reorder the list of functions by decreasing order of preference
   of use.
3) Rework part of the kmap() entry in list.

Link: https://lkml.kernel.org/r/20220428212455.892-5-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/vm: move "Using kmap-atomic" to highmem.h

The use of kmap_atomic() is new code is being deprecated in favor of
kmap_local_page().  For this reason the "Using kmap_atomic" section in
highmem.rst is obsolete and unnecessary, but it can still help developers
if it were moved to kdocs in highmem.h.

Therefore, move the relevant parts of this section from highmem.rst and
merge them with the kdocs in highmem.h.

Link: https://lkml.kernel.org/r/20220428212455.892-4-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/vm: include kdocs from highmem*.h into highmem.rst

kernel-docs that are in include/linux/highmem.h and in
include/linux/highmem-internal.h should be included in highmem.rst.

Use kdocs directives to include the above-mentioned comments into
highmem.rst.

Link: https://lkml.kernel.org/r/20220428212455.892-3-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/highmem: fix kernel-doc warnings in highmem*.h

Patch series "Extend and reorganize Highmem's documentation", v4.

This series has the purpose to extend and reorganize Highmem's
documentation.

This is a work in progress because some information should still be moved
from highmem.rst to highmem.h and highmem-internal.h.  Specifically I'm
talking about moving the "how to" information to the relevant headers, as
it as been suggested by Ira Weiny (Intel).

Also, this is a work in progress because some kdocs in highmem.h and
highmem-internal.h should be improved.

This patch (of 4):

`scripts/kernel-doc -v -none include/linux/highmem*` reports the following
warnings:

include/linux/highmem.h:160: warning: expecting prototype for kunmap_atomic(). Prototype was for nr_free_highpages() instead
include/linux/highmem.h:204: warning: No description found for return value of 'alloc_zeroed_user_highpage_movable'
include/linux/highmem-internal.h:256: warning: Function parameter or member '__addr' not described in 'kunmap_atomic'
include/linux/highmem-internal.h:256: warning: Excess function parameter 'addr' description in 'kunmap_atomic'

Fix these warnings by (1) moving the kernel-doc comments from highmem.h to
highmem-internal.h (which is the file were the kunmap_atomic() macro is
actually defined), (2) extending and merging it with the comment which was
already in highmem-internal.h, and (3) using correct parameter names (4)
correcting a few technical inaccuracies in comments, and (5) adding a
deprecation notice in kunmap_atomic() for consistency with kmap_atomic().

Link: https://lkml.kernel.org/r/20220428212455.892-1-fmdefrancesco@gmail.com
Link: https://lkml.kernel.org/r/20220428212455.892-2-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c: simplify num_poisoned_pages_inc/dec

Originally, do num_poisoned_pages_inc() in memory failure routine, use
num_poisoned_pages_dec() to rollback the number if filtered/ cancelled.

Suggested by Naoya, do num_poisoned_pages_inc() only in action_result(),
this make this clear and simple.

Link: https://lkml.kernel.org/r/20220509105641.491313-6-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hwpoison: disable hwpoison filter during removing

hwpoison filter is enabled by hwpoison-inject module, after removing this
module, hwpoison filter still works.  What is worse, user can not find the
debugfs entries to know this.

Disable the hwpoison filter during removing hwpoison-inject module.

Link: https://lkml.kernel.org/r/20220509105641.491313-5-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c: add hwpoison_filter for soft offline

hwpoison_filter is missing in the soft offline path, this leads an issue:
after enabling the corrupt filter, the user process still has a chance to
inject hwpoison fault by madvise(addr, len, MADV_SOFT_OFFLINE) at PFN
which is expected to reject.

Also do a minor change in comment of memory_failure().

Link: https://lkml.kernel.org/r/20220509105641.491313-4-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c: simplify num_poisoned_pages_dec

Don't decrease the number of poisoned pages in page_alloc.c, let the
memory-failure.c do inc/dec poisoned pages only.

Also simplify unpoison_memory(), only decrease the number of
poisoned pages when:
 - TestClearPageHWPoison() succeed
 - put_page_back_buddy succeed

After decreasing, print necessary log.

Finally, remove clear_page_hwpoison() and unpoison_taken_off_page().

Link: https://lkml.kernel.org/r/20220509105641.491313-3-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c: move clear_hwpoisoned_pages

Patch series "memory-failure: fix hwpoison_filter", v2.

As well known, the memory failure mechanism handles memory corrupted
event, and try to send SIGBUS to the user process which uses this
corrupted page.

For the virtualization case, QEMU catches SIGBUS and tries to inject MCE
into the guest, and the guest handles memory failure again.  Thus the
guest gets the minimal effect from hardware memory corruption.

The further step I'm working on:

1, try to modify code to decrease poisoned pages in a single place
   (mm/memofy-failure.c: simplify num_poisoned_pages_dec in this series).

2, try to use page_handle_poison() to handle SetPageHWPoison() and
   num_poisoned_pages_inc() together.  It would be best to call
   num_poisoned_pages_inc() in a single place too.

3, introduce memory failure notifier list in memory-failure.c: notify
   the corrupted PFN to someone who registers this list.  If I can
   complete [1] and [2] part, [3] will be quite easy(just call notifier
   list after increasing poisoned page).

4, introduce memory recover VQ for memory balloon device, and registers
   memory failure notifier list.  During the guest kernel handles memory
   failure, balloon device gets notified by memory failure notifier list,
   and tells the host to recover the corrupted PFN(GPA) by the new VQ.

5, host side remaps the corrupted page(HVA), and tells the guest side
   to unpoison the PFN(GPA).  Then the guest fixes the corrupted page(GPA)
   dynamically.

This patch (of 5):

clear_hwpoisoned_pages() clears HWPoison flag and decreases the number of
poisoned pages, this actually works as part of memory failure.

Move this function from sparse.c to memory-failure.c, finally there is no
CONFIG_MEMORY_FAILURE in sparse.c.

Link: https://lkml.kernel.org/r/20220509105641.491313-1-pizhenwei@bytedance.com
Link: https://lkml.kernel.org/r/20220509105641.491313-2-pizhenwei@bytedance.com
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_owner: use strscpy() instead of strlcpy()

current->comm[] is not a string (no guarantee for a zero byte in it).

strlcpy(s1, s2, l) is calling strlen(s2), potentially
causing out-of-bound access, as reported by syzbot:

detected buffer overflow in __fortify_strlen
------------[ cut here ]------------
kernel BUG at lib/string_helpers.c:980!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4087 Comm: dhcpcd-run-hooks Not tainted 5.18.0-rc3-syzkaller-01537-g20b87e7c29df #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fortify_panic+0x18/0x1a lib/string_helpers.c:980
Code: 8c e8 c5 ba e1 fa e9 23 0f bf fa e8 0b 5d 8c f8 eb db 55 48 89 fd e8 e0 49 40 f8 48 89 ee 48 c7 c7 80 f5 26 8a e8 99 09 f1 ff <0f> 0b e8 ca 49 40 f8 48 8b 54 24 18 4c 89 f1 48 c7 c7 00 00 27 8a
RSP: 0018:ffffc900000074a8 EFLAGS: 00010286

RAX: 000000000000002c RBX: ffff88801226b728 RCX: 0000000000000000
RDX: ffff8880198e0000 RSI: ffffffff81600458 RDI: fffff52000000e87
RBP: ffffffff89da2aa0 R08: 000000000000002c R09: 0000000000000000
R10: ffffffff815fae2e R11: 0000000000000000 R12: ffff88801226b700
R13: ffff8880198e0830 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5876ad6ff8 CR3: 000000001a48c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __fortify_strlen include/linux/fortify-string.h:128 [inline]
 strlcpy include/linux/fortify-string.h:143 [inline]
 __set_page_owner_handle+0x2b1/0x3e0 mm/page_owner.c:171
 __set_page_owner+0x3e/0x50 mm/page_owner.c:190
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272
 alloc_slab_page mm/slub.c:1799 [inline]
 allocate_slab+0x26c/0x3c0 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x8df/0xf20 mm/slub.c:3005
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3242
 dst_alloc+0x146/0x1f0 net/core/dst.c:92

Link: https://lkml.kernel.org/r/20220509145949.265184-1-eric.dumazet@gmail.com
Fixes: 865ed6a32786 ("mm/page_owner: record task command name")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Acked-by: Waiman Long <longman@redhat.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: clean-up kconfig options descriptions

Various readability clean-ups of KASAN Kconfig options.

No functional changes.

Link: https://lkml.kernel.org/r/c160840dd9e4b1ad5529ecfdb0bba35d9a14d826.1652203271.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/47afaecec29221347bee49f58c258ac1ced3b429.1652123204.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: move boot parameters section in documentation

Move the "Boot parameters" section in KASAN documentation next to the
section that describes KASAN build options.

No content changes.

Link: https://lkml.kernel.org/r/870628e1293b4f44edf7cbcb92374ff9eb7503d7.1652203271.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/ec9c923f35e7c5312836c4624a7f317dc1ee2c1c.1652123204.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: update documentation

Do assorted clean-ups and improvements to KASAN documentation, including:

- Describe each mode in a dedicated paragraph.
- Split out a Support section that describes in details which compilers,
  architectures and memory types each mode requires/supports.
- Capitalize the first letter in the names of each KASAN mode.

[andreyknvl@google.com: rewording, per Marco]
Link: https://lkml.kernel.org/r/896b2d914d6b50d677fd7b38f76967cc705c01ba.1652203271.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/5bd58ebebf066593ce0e1d265d60278b5f5a1874.1652123204.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: give better names to shadow values

Rename KASAN_KMALLOC_* shadow values to KASAN_SLAB_*, as they are used for
all slab allocations, not only for kmalloc.

Also rename KASAN_FREE_PAGE to KASAN_PAGE_FREE to be consistent with
KASAN_PAGE_REDZONE and KASAN_SLAB_FREE.

Link: https://lkml.kernel.org/r/bebcaf4eafdb0cabae0401a69c0af956aa87fcaa.1652111464.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: use tabs to align shadow values

Consistently use tabs instead of spaces to shadow value definitions.

Link: https://lkml.kernel.org/r/00e7e66b5fc375d58200dc1489949b3edcd096b7.1652111464.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

kasan: clean up comments in internal kasan.h

Clean up comments in mm/kasan/kasan.h: clarify, unify styles, fix
punctuation, etc.

Link: https://lkml.kernel.org/r/a0680ff30035b56cb7bdd5f59fd400e71712ceb5.1652111464.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmalloc: use raw_cpu_ptr() for vmap_block_queue access

The per-CPU resource vmap_block_queue is accessed via get_cpu_var().  That
macro disables preemption and then loads the pointer from the current CPU.

This doesn't work on PREEMPT_RT because a spinlock_t is later accessed
within the preempt-disable section.

There is no need to disable preemption while accessing the per-CPU struct
vmap_block_queue because the list is protected with a spinlock_t.  The
per-CPU struct is also accessed cross-CPU in purge_fragmented_blocks().

It is possible that by using raw_cpu_ptr() the code migrates to another
CPU and uses struct from another CPU.  This is fine because the list is
locked and the locked section is very short.

Use raw_cpu_ptr() to access vmap_block_queue.

Link: https://lkml.kernel.org/r/YnKx3duAB53P7ojN@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tracing: incorrect gfp_t conversion

Fixes the following sparse warnings:

include/trace/events/*: sparse: cast to restricted gfp_t
include/trace/events/*: sparse: restricted gfp_t degrades to integer

gfp_t type is bitwise and requires __force attributes for any casts.

Link: https://lkml.kernel.org/r/331d88fe-f4f7-657c-02a2-d977f15fbff6@openvz.org
Signed-off-by: Vasily Averin <vvs@openvz.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

zram: remove double compression logic

The 2nd trial allocation under per-cpu presumption has been used to
prevent regression of allocation failure.  However, it makes trouble for
maintenance without significant benefit.  The slowpath branch is executed
extremely rarely: getting there is problematic.  Therefore, we delete this
branch.

Since b09ab054b69b ("zram: support BDI_CAP_STABLE_WRITES"), zram has used
QUEUE_FLAG_STABLE_WRITES to prevent buffer change between 1st and 2nd
memory allocations.  Since we remove second trial memory allocation logic,
we could remove the STABLE_WRITES flag because there is no change buffer
to be modified under us.

Link: https://lkml.kernel.org/r/20220505094443.11728-1-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

percpu: improve percpu_alloc_percpu event trace

Add call_site, bytes_alloc and gfp_flags fields to the output of the
percpu_alloc_percpu ftrace event:

mkdir-4393  [001]   169.334788: percpu_alloc_percpu:
 call_site=mem_cgroup_css_alloc+0xa6 reserved=0 is_atomic=0 size=2408 align=8
  base_addr=0xffffc7117fc00000 off=402176 ptr=0x3dc867a62300 bytes_alloc=14448
   gfp_flags=GFP_KERNEL_ACCOUNT

This is required to track memcg-accounted percpu allocations.

Link: https://lkml.kernel.org/r/a07be858-c8a3-7851-9086-e3262cbcf707@openvz.org
Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

docs: vm/page_owner: tweak literal block in STANDARD FORMAT SPECIFIERS

A semantic conflict between commit 5603f9bdea68 ("docs: vm/page_owner: use
literal blocks for param description") and a change queued for v5.19
authored by Jiajian Ye ("tools/vm/page_owner_sort.c: support sorting
blocks by multiple keys") results in a warning from "make htmldocs"
saying:

  [...]/vm/page_owner.rst:176: WARNING: Literal block expected; none found.

This is because a literal block in ReST ends at a line which has the same
indent as the paragraph preceding it.  In this case the one with no
indent.

Indent the two "For --xxxx option:" lines by two columns and make the
whole section a literal block.

While at it, fix indents by white spaces of "ator" keys.

Link: https://lkml.kernel.org/r/fdfecc82-d41e-6d8a-738d-4beb6faa27fb@gmail.com
Signed-of-by: Akira Yokosawa <akiyks@gmail.com>
Reported-by: Shenghong Han <hanshenghong2019@email.szu.edu.cn>
Cc: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Chongxi Zhao <zhaochongxi2019@email.szu.edu.cn>
Cc: Yinan Zhang <zhangyinan2019@email.szu.edu.cn>
Cc: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Yongqiang Liu <liuyongqiang13@huawei.com>
Cc: Yuhong Feng <yuhongf@szu.edu.cn>
Cc: Haowen Bai <baihaowen@meizu.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/reclaim: use resource_size function on resource object

Fix the following coccicheck warnings:

./mm/damon/reclaim.c:241:30-33: WARNING: Suspicious code. resource_size is maybe missing with res.

Link: https://lkml.kernel.org/r/20220507032512.129598-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: "Boehme, Markus" <markubo@amazon.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: functions may simplify the use of return values

p4d_clear_huge may be optimized for void return type and function usage.
vunmap_p4d_range function saves a few steps here.

Link: https://lkml.kernel.org/r/20220507150630.90399-1-kunyu@nfschina.com
Signed-off-by: Li kunyu <kunyu@nfschina.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

riscv/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK

As commit d283d422c6c4 ("x86: mm: add x86_64 support for page table
check"), enable ARCH_SUPPORTS_PAGE_TABLE_CHECK on riscv.

Add additional page table check stubs for page table helpers, these stubs
can be used to check the existing page table entries.

Link: https://lkml.kernel.org/r/20220507110114.4128854-7-tongtiangen@huawei.com
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK

As commit d283d422c6c4 ("x86: mm: add x86_64 support for page table
check") , enable ARCH_SUPPORTS_PAGE_TABLE_CHECK on arm64.

Add additional page table check stubs for page table helpers, these stubs
can be used to check the existing page table entries.

Link: https://lkml.kernel.org/r/20220507110114.4128854-6-tongtiangen@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: remove __HAVE_ARCH_PTEP_CLEAR in pgtable.h

Currently, there is no architecture definition __HAVE_ARCH_PTEP_CLEAR,
Generic ptep_clear() is the only definition for all architecture, So drop
the "#ifndef __HAVE_ARCH_PTEP_CLEAR".

Link: https://lkml.kernel.org/r/20220507110114.4128854-5-tongtiangen@huawei.com
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Suggested-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_table_check: add hooks to public helpers

Move ptep_clear() to the include/linux/pgtable.h and add page table check
relate hooks to some helpers, it's prepare for support page table check
feature on new architecture.

Optimize the implementation of ptep_clear(), page table hooks added page
table check stubs, the interface control should be at stubs, there is no
rationale for doing a IS_ENABLED() check here.

For architectures that do not enable CONFIG_PAGE_TABLE_CHECK, they will
call a fallback page table check stubs[1] when getting their page table
helpers[2] in include/linux/pgtable.h.

[1] page table check stubs defined in include/linux/page_table_check.h
[2] ptep_clear() ptep_get_and_clear()  pmdp_huge_get_and_clear()
pudp_huge_get_and_clear()

Link: https://lkml.kernel.org/r/20220507110114.4128854-4-tongtiangen@huawei.com
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_table_check: move pxx_user_accessible_page into x86

The pxx_user_accessible_page() checks the PTE bit, it's
architecture-specific code, move them into x86's pgtable.h.

These helpers are being moved out to make the page table check framework
platform independent.

Link: https://lkml.kernel.org/r/20220507110114.4128854-3-tongtiangen@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_table_check: using PxD_SIZE instead of PxD_PAGE_SIZE

Patch series "mm: page_table_check: add support on arm64 and riscv", v7.

Page table check performs extra verifications at the time when new pages
become accessible from the userspace by getting their page table entries
(PTEs PMDs etc.) added into the table.  It is supported on X86[1].

This patchset made some simple changes and make it easier to support new
architecture, then we support this feature on ARM64 and RISCV.

[1]https://lore.kernel.org/lkml/20211123214814.3756047-1-pasha.tatashin@soleen.com/

This patch (of 6):

Compared with PxD_PAGE_SIZE, which is defined and used only on X86,
PxD_SIZE is more common in each architecture.  Therefore, it is more
reasonable to use PxD_SIZE instead of PxD_PAGE_SIZE in page_table_check.c.
At the same time, it is easier to support page table check in other
architectures.  The substitution has no functional impact on the x86.

Link: https://lkml.kernel.org/r/20220507110114.4128854-1-tongtiangen@huawei.com
Link: https://lkml.kernel.org/r/20220507110114.4128854-2-tongtiangen@huawei.com
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Suggested-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate: convert move_to_new_page() into move_to_new_folio()

Pass in the folios that we already have in each caller.  Saves a
lot of calls to compound_head().

Link: https://lkml.kernel.org/r/20220504182857.4013401-27-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: add folio_test_movable()

This is the folio equivalent of PageMovable() which is needed to
convert mm/migrate.c to folios.

Link: https://lkml.kernel.org/r/20220504182857.4013401-26-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: add folio_mapping_flags()

This is the equivalent of PageMappingFlags and is needed for converting
mm/migrate.c to folios.

Link: https://lkml.kernel.org/r/20220504182857.4013401-25-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/shmem: convert shmem_swapin_page() to shmem_swapin_folio()

shmem_swapin_page() only brings in order-0 pages, which are folios
by definition.

Link: https://lkml.kernel.org/r/20220504182857.4013401-24-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/shmem: convert shmem_getpage_gfp to use a folio

Rename shmem_alloc_and_acct_page() to shmem_alloc_and_acct_folio() and
have it return a folio, then use a folio throuughout shmem_getpage_gfp().
It continues to return a struct page.

Link: https://lkml.kernel.org/r/20220504182857.4013401-23-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/shmem: convert shmem_alloc_and_acct_page to use a folio

Convert shmem_alloc_hugepage() to return the folio that it uses and use a
folio throughout shmem_alloc_and_acct_page().  Continue to return a page
from shmem_alloc_and_acct_page() for now.

Link: https://lkml.kernel.org/r/20220504182857.4013401-22-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/shmem: add shmem_alloc_folio()

Call vma_alloc_folio() directly instead of alloc_page_vma().  Add a
shmem_alloc_page() wrapper to avoid changing the callers.

Link: https://lkml.kernel.org/r/20220504182857.4013401-21-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/shmem: turn shmem_should_replace_page into shmem_should_replace_folio

This is a straightforward conversion.

Link: https://lkml.kernel.org/r/20220504182857.4013401-20-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/shmem: convert shmem_add_to_page_cache to take a folio

Shrinks shmem_add_to_page_cache() by 16 bytes.  All the callers grow,
but this is temporary as they will all be converted to folios soon.

Link: https://lkml.kernel.org/r/20220504182857.4013401-19-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/swap: add folio_throttle_swaprate

The only use of the page argument to cgroup_throttle_swaprate() is to get
the node ID, and this will be the same for all pages in the folio, so just
pass in the first page of the folio.

Link: https://lkml.kernel.org/r/20220504182857.4013401-18-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/shmem: use a folio in shmem_unused_huge_shrink

When calling split_huge_page() we usually have to find the precise page,
but that's not necessary here because we only need to unlock and put the
folio afterwards.  Saves 231 bytes of text (20% of this function).

Link: https://lkml.kernel.org/r/20220504182857.4013401-17-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>

vmscan: remove remaining uses of page in shrink_page_list

These are all straightforward conversions to the folio API.

Link: https://lkml.kernel.org/r/20220504182857.4013401-16-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: allow can_split_folio() to be called when THP are disabled

The call to can_split_folio() in vmscan is currently guarded by a test of
PageTransHuge() so the BUILD_BUG() is eliminated if THP are disabled.  The
next patch replaces that test with folio_test_large() which may be true,
even when THP are disabled.  However, if THP are disabled, we cannot
split, so an unconditional return of false is appropriate.

Link: https://lkml.kernel.org/r/20220504182857.4013401-15-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>

vmscan: convert the activate_locked portion of shrink_page_list to folios

This accounts the number of pages activated correctly for large folios.

Link: https://lkml.kernel.org/r/20220504182857.4013401-14-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>

vmscan: move initialisation of mapping down

Now that we don't interrogate the BDI for congestion, we can delay looking
up the folio's mapping until we've got further through the function,
reducing register pressure and saving a call to folio_mapping for folios
we're adding to the swap cache.

Link: https://lkml.kernel.org/r/20220504182857.4013401-13-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>

vmscan: convert lazy freeing to folios

Remove a hidden call to compound_head(), and account nr_pages instead of a
single page.  This matches the code in lru_lazyfree_fn() that accounts
nr_pages to PGLAZYFREE.

Link: https://lkml.kernel.org/r/20220504182857.4013401-12-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>

vmscan: convert page buffer handling to use folios

This mostly just removes calls to compound_head() although nr_reclaimed
should be incremented by the number of pages, not just 1.

Link: https://lkml.kernel.org/r/20220504182857.4013401-11-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>

vmscan: convert dirty page handling to folios

Mostly this just eliminates calls to compound_head(), but
NR_VMSCAN_IMMEDIATE was being incremented by 1 instead of by nr_pages.

Link: https://lkml.kernel.org/r/20220504182857.4013401-10-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>

swap: convert add_to_swap() to take a folio

The only caller already has a folio available, so this saves a conversion.
Also convert the return type to boolean.

Link: https://lkml.kernel.org/r/20220504182857.4013401-9-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>

swap: turn get_swap_page() into folio_alloc_swap()

This removes an assumption that a large folio is HPAGE_PMD_NR pages
in size.

Link: https://lkml.kernel.org/r/20220504182857.4013401-8-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>

vmscan: convert the writeback handling in shrink_page_list() to folios

Slightly more efficient due to fewer calls to compound_head().

Link: https://lkml.kernel.org/r/20220504182857.4013401-7-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>

vmscan: use folio_mapped() in shrink_page_list()

Remove some legacy function calls.

Link: https://lkml.kernel.org/r/20220504182857.4013401-6-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: remove alloc_pages_vma()

All callers have now been converted to use vma_alloc_folio(), so convert
the body of alloc_pages_vma() to allocate folios instead.

Link: https://lkml.kernel.org/r/20220504182857.4013401-5-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>

alpha: fix alloc_zeroed_user_highpage_movable()

Due to a typo, the final argument to alloc_page_vma() didn't refer to a
real variable.  This only affected CONFIG_NUMA, which was marked BROKEN in
2006 and removed from alpha in 2021.  Found due to a refactoring patch.

Link: https://lkml.kernel.org/r/20220504182857.4013401-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/huge_memory: convert do_huge_pmd_anonymous_page() to use vma_alloc_folio()

Remove the use of this old API, eliminating a call to
prep_transhuge_page().

Link: https://lkml.kernel.org/r/20220504182857.4013401-3-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>

shmem: convert shmem_alloc_hugepage() to use vma_alloc_folio()

Patch series "Folio patches for 5.19", v2.

This patch (of 26):

For now, return the head page of the folio, but remove use of the old
alloc_pages_vma() API.

Link: https://lkml.kernel.org/r/20220504182857.4013401-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20220504182857.4013401-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/shmem: remove duplicate include in memory.c

Fix following checkincludes.pl warning:
mm/memory.c: linux/mm_inline.h is included more than once.

The include is in line 44. Remove the duplicated here.

Link: https://lkml.kernel.org/r/20220427064717.803019-1-wanjiabing@vivo.com
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: don't use NUMA_NO_NODE as indicator of page on different node

Now we are sure there is at least one page on page_list, so it is safe to
get the nid of it.  This means it is not necessary to use NUMA_NO_NODE as
an indicator for the beginning of iteration or a page on different node.

Link: https://lkml.kernel.org/r/20220429014426.29223-2-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: filter empty page_list at the beginning

node_page_list would always be !empty on finishing the loop, except
page_list is empty.

Let's handle empty page_list before doing any real work including touching
PF_MEMALLOC flag.

Link: https://lkml.kernel.org/r/20220429014426.29223-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: use helper folio_is_file_lru()

Use helper folio_is_file_lru() to check whether folio is file lru.  Minor
readability improvement.

[linmiaohe@huawei.com: use folio_is_file_lru()]
Link: https://lkml.kernel.org/r/20220428105802.21389-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220425111232.23182-7-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: remove obsolete comment in kswapd_run

Since commit 6b700b5b3c59 ("mm/vmscan.c: remove cpu online notification
for now"), cpu online notification is removed.  So kswapd won't move to
proper cpus if cpus are hot-added.  Remove this obsolete comment.

Link: https://lkml.kernel.org/r/20220425111232.23182-6-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: take all base pages of THP into account when race with speculative reference

If the page has buffers, shrink_page_list will try to free the buffer
mappings associated with the page and try to free the page as well.  In
the rare race with speculative reference, the page will be freed shortly
by speculative reference.  But nr_reclaimed is not incremented correctly
when we come across the THP.  We need to account all the base pages in
this case.

Link: https://lkml.kernel.org/r/20220425111232.23182-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: introduce helper function reclaim_page_list()

Introduce helper function reclaim_page_list() to eliminate the duplicated
code of doing shrink_page_list() and putback_lru_page.  Also we can
separate node reclaim from node page list operation this way.  No
functional change intended.

Link: https://lkml.kernel.org/r/20220425111232.23182-3-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: add a comment about MADV_FREE pages check in folio_check_dirty_writeback

Patch series "A few cleanup and fixup patches for vmscan

This series contains a few patches to remove obsolete comment, introduce
helper to remove duplicated code and so no.  Also we take all base pages
of THP into account in rare race condition.  More details can be found in
the respective changelogs.

This patch (of 6):

The MADV_FREE pages check in folio_check_dirty_writeback is a bit hard to
follow.  Add a comment to make the code clear.

Link: https://lkml.kernel.org/r/20220425111232.23182-2-linmiaohe@huawei.com
Suggested-by: Huang, Ying <ying.huang@intel.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: not necessary to re-init the list for each iteration

node_page_list is defined with LIST_HEAD and be cleaned until
list_empty.

So it is not necessary to re-init it again.

[akpm@linux-foundation.org: remove unneeded braces]
Link: https://lkml.kernel.org/r/20220426021743.21007-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: convert sysfs input to bool using kstrtobool()

Sysfs input conversion to corrosponding bool value e.g.  "false" or "0" to
false, "true" or "1" to true are currently handled through strncmp at
multiple places.  Use kstrtobool() to convert sysfs input to bool value.

[akpm@linux-foundation.org: propagate kstrtobool() return value, per Andy]
Link: https://lkml.kernel.org/r/20220426180203.70782-2-jvgediya@linux.ibm.com
Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/kstrtox.c: add "false"/"true" support to kstrtobool()

At many places in kernel, It is necessary to convert sysfs input to
corresponding bool value e.g.  "false" or "0" need to be converted to bool
false, "true" or "1" need to be converted to bool true, places where such
conversion is needed currently check the input string manually,
kstrtobool() can be utilized at such places but currently it doesn't have
support to accept "false"/"true".

Add support to accept "false"/"true" as valid string in kstrtobool().

[akpm@linux-foundation.org: undo s/iff/if/, per Matthew]
Link: https://lkml.kernel.org/r/20220426180203.70782-1-jvgediya@linux.ibm.com
Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Richard Fitzgerald <rf@opensource.cirrus.com>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan: take min_slab_pages into account when try to call shrink_node

Since commit 6b4f7799c6a5 ("mm: vmscan: invoke slab shrinkers from
shrink_zone()"), slab reclaim and lru page reclaim are done together in
the shrink_node.  So we should take min_slab_pages into account when try
to call shrink_node.

Link: https://lkml.kernel.org/r/20220425112118.20924-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers: virtio_mem: use pageblock size as the minimum virtio_mem size.

alloc_contig_range() now only needs to be aligned to pageblock_nr_pages,
drop virtio_mem size requirement that it needs to be MAX_ORDER_NR_PAGES.

Link: https://lkml.kernel.org/r/20220425143118.2850746-7-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: cma: use pageblock_order as the single alignment

Now alloc_contig_range() works at pageblock granularity.  Change CMA
allocation, which uses alloc_contig_range(), to use pageblock_nr_pages
alignment.

Link: https://lkml.kernel.org/r/20220425143118.2850746-6-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_isolation: enable arbitrary range page isolation.

Now start_isolate_page_range() is ready to handle arbitrary range
isolation, so move the alignment check/adjustment into the function body.
Do the same for its counterpart undo_isolate_page_range().
alloc_contig_range(), its caller, can pass an arbitrary range instead of a
MAX_ORDER_NR_PAGES aligned one.

Link: https://lkml.kernel.org/r/20220425143118.2850746-5-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: make alloc_contig_range work at pageblock granularity

alloc_contig_range() worked at MAX_ORDER_NR_PAGES granularity to avoid
merging pageblocks with different migratetypes.  It might unnecessarily
convert extra pageblocks at the beginning and at the end of the range.
Change alloc_contig_range() to work at pageblock granularity.

Special handling is needed for free pages and in-use pages across the
boundaries of the range specified by alloc_contig_range().  Because these=

Partially isolated pages causes free page accounting issues.  The free
pages will be split and freed into separate migratetype lists; the in-use=

Pages will be migrated then the freed pages will be handled in the
aforementioned way.

[ziy@nvidia.com: fix deadlock/crash]
Link: https://lkml.kernel.org/r/23A7297E-6C84-4138-A9FE-3598234004E6@nvidia.com
Link: https://lkml.kernel.org/r/20220425143118.2850746-4-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_isolation: check specified range for unmovable pages

Enable set_migratetype_isolate() to check specified range for unmovable
pages during isolation to prepare arbitrary range page isolation.  The
functionality will take effect in upcoming commits by adjusting the
callers of start_isolate_page_range(), which uses
set_migratetype_isolate().

For example, alloc_contig_range(), which calls start_isolate_page_range(),
accepts unaligned ranges, but because page isolation is currently done at
MAX_ORDER_NR_PAEGS granularity, pages that are out of the specified range
but withint MAX_ORDER_NR_PAEGS alignment might be attempted for isolation
and the failure of isolating these unrelated pages fails the whole
operation undesirably.

Link: https://lkml.kernel.org/r/20220425143118.2850746-3-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: page_isolation: move has_unmovable_pages() to mm/page_isolation.c

Patch series "Use pageblock_order for cma and alloc_contig_range alignment", v11.

This patchset tries to remove the MAX_ORDER-1 alignment requirement for CMA
and alloc_contig_range(). It prepares for my upcoming changes to make
MAX_ORDER adjustable at boot time[1].

The MAX_ORDER - 1 alignment requirement comes from that
alloc_contig_range() isolates pageblocks to remove free memory from buddy
allocator but isolating only a subset of pageblocks within a page spanning
across multiple pageblocks causes free page accounting issues.  Isolated
page might not be put into the right free list, since the code assumes the
migratetype of the first pageblock as the whole free page migratetype.
This is based on the discussion at [2].

To remove the requirement, this patchset:
1. isolates pages at pageblock granularity instead of
   max(MAX_ORDER_NR_PAEGS, pageblock_nr_pages);
2. splits free pages across the specified range or migrates in-use pages
   across the specified range then splits the freed page to avoid free page
   accounting issues (it happens when multiple pageblocks within a single page
   have different migratetypes);
3. only checks unmovable pages within the range instead of MAX_ORDER - 1 aligned
   range during isolation to avoid alloc_contig_range() failure when pageblocks
   within a MAX_ORDER - 1 aligned range are allocated separately.
4. returns pages not in the range as it did before.

One optimization might come later:
1. make MIGRATE_ISOLATE a separate bit to be able to restore the original
   migratetypes when isolation fails in the middle of the range.

[1] https://lore.kernel.org/linux-mm/20210805190253.2795604-1-zi.yan@sent.com/
[2] https://lore.kernel.org/linux-mm/d19fb078-cb9b-f60f-e310-fdeea1b947d2@redhat.com/

This patch (of 6):

has_unmovable_pages() is only used in mm/page_isolation.c.  Move it from
mm/page_alloc.c and make it static.

Link: https://lkml.kernel.org/r/20220425143118.2850746-2-zi.yan@sent.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Eric Ren <renzhengeek@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cgroup: fix racy check in alloc_pagecache_max_30M() helper function

alloc_pagecache_max_30M() in the cgroup memcg tests performs a 50MB
pagecache allocation, which it expects to be capped at 30MB due to the
calling process having a memory.high setting of 30MB.  After the
allocation, the function contains a check that verifies that MB(29) <
memory.current <= MB(30).  This check can actually fail
non-deterministically.

The testcases that use this function are test_memcg_high() and
test_memcg_max(), which set memory.min and memory.max to 30MB respectively
for the cgroup under test.  The allocation can slightly exceed this number
in both cases, and for memory.max, the process performing the allocation
will not have the OOM killer invoked as it's performing a pagecache
allocation.  This patchset therefore updates the above check to instead
use the verify_close() helper function.

Link: https://lkml.kernel.org/r/20220423155619.3669555-6-void@manifault.com
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cgroup: remove racy check in test_memcg_sock()

test_memcg_sock() in the cgroup memcg tests, verifies expected memory
accounting for sockets.  The test forks a process which functions as a TCP
server, and sends large buffers back and forth between itself (as the TCP
client) and the forked TCP server.  While doing so, it verifies that
memory.current and memory.stat.sock look correct.

There is currently a check in tcp_client() which asserts memory.current >=
memory.stat.sock.  This check is racy, as between memory.current and
memory.stat.sock being queried, a packet could come in which causes
mem_cgroup_charge_skmem() to be invoked.  This could cause
memory.stat.sock to exceed memory.current.  Reversing the order of
querying doesn't address the problem either, as memory may be reclaimed
between the two calls.  Instead, this patch just removes that assertion
altogether, and instead relies on the values_close() check that follows to
validate the expected accounting.

Link: https://lkml.kernel.org/r/20220423155619.3669555-5-void@manifault.com
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cgroup: account for memory_localevents in test_memcg_oom_group_leaf_events()

The test_memcg_oom_group_leaf_events() testcase in the cgroup memcg tests
validates that processes in a group that perform allocations exceeding
memory.oom.group are killed.  It also validates that the
memory.events.oom_kill events are properly propagated in this case.

Commit 06e11c907ea4 ("kselftests: memcg: update the oom group leaf events
test") fixed test_memcg_oom_group_leaf_events() to account for the fact
that the memory.events.oom_kill events in a child cgroup is propagated up
to its parent.  This behavior can actually be configured by the
memory_localevents mount option, so this patch updates the testcase to
properly account for the possible presence of this mount option.

Link: https://lkml.kernel.org/r/20220423155619.3669555-4-void@manifault.com
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cgroup: account for memory_recursiveprot in test_memcg_low()

The test_memcg_low() testcase in test_memcontrol.c verifies the expected
behavior of groups using the memory.low knob.  Part of the testcase
verifies that a group with memory.low that experiences reclaim due to
memory pressure elsewhere in the system, observes memory.events.low events
as a result of that reclaim.

In commit 8a931f801340 ("mm: memcontrol: recursive memory.low
protection"), the memory controller was updated to propagate memory.low
and memory.min protection from a parent group to its children via a
configurable memory_recursiveprot mount option.  This unfortunately broke
the memcg tests, which asserts that a sibling that experienced reclaim but
had a memory.low value of 0, would not observe any memory.low events.
This patch updates test_memcg_low() to account for the new behavior
introduced by memory_recursiveprot.

So as to make the test resilient to multiple configurations, the patch
also adds a new proc_mount_contains() helper that checks for a string in
/proc/mounts, and is used to toggle behavior based on whether the default
memory_recursiveprot was present.

Link: https://lkml.kernel.org/r/20220423155619.3669555-3-void@manifault.com
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

cgroups: refactor children cgroups in memcg tests

Patch series "Fix bugs in memcontroller cgroup tests", v2.

tools/testing/selftests/cgroup/test_memcontrol.c contains a set of
testcases which validate expected behavior of the cgroup memory
controller.  Roman Gushchin recently sent out a patchset that fixed a few
issues in the test.  This patchset continues that effort by fixing a few
more issues that were causing non-deterministic failures in the suite.
With this patchset, I'm unable to reproduce any more errors after running
the tests in a continuous loop for many iterations.  Before, I was able to
reproduce at least one of the errors fixed in this patchset with just one
or two runs.

This patch (of 5):

In test_memcg_min() and test_memcg_low(), there is an array of four
sibling cgroups.  All but one of these sibling groups does a 50MB
allocation, and the group that does no allocation is the third of four in
the array.  This is not a problem per se, but makes it a bit tricky to do
some assertions in test_memcg_low(), as we want to make assertions on the
siblings based on whether or not they performed allocations.  Having a
static index before which all groups have performed an allocation makes
this cleaner.

This patch therefore reorders the sibling groups so that the group that
performs no allocations is the last in the array.  A follow-on patch will
leverage this to fix a bug in the test that incorrectly asserts that a
sibling group that had performed an allocation, but only had protection
from its parent, will not observe any memory.events.low events during
reclaim.

Link: https://lkml.kernel.org/r/20220423155619.3669555-1-void@manifault.com
Link: https://lkml.kernel.org/r/20220423155619.3669555-2-void@manifault.com
Signed-off-by: David Vernet <void@manifault.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/uffd: move USERFAULTFD configs into mm/

We used to have USERFAULTFD configs stored in init/.  It makes sense as a
start because that's the default place for storing syscall related
configs.

However userfaultfd evolved a bit in the past few years and some more
config options were added.  They're no longer related to syscalls and
start to be not suitable to be kept in the init/ directory anymore,
because they're pure mm concepts.

But it's not ideal either to keep the userfaultfd configs separate from
each other.  Hence this patch moves the userfaultfd configs under init/ to
be under mm/ so that we'll start to group all userfaultfd configs
together.

We do have quite a few examples of syscall related configs that are not
put under init/Kconfig: FTRACE_SYSCALLS, SWAP, FILE_LOCKING,
MEMFD_CREATE..  They all reside in the dir where they're more suitable for
the concept.  So it seems there's no restriction to keep the role of
having syscall related CONFIG_* under init/ only.

Link: https://lkml.kernel.org/r/20220420144823.35277-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

userfaultfd/selftests: use swap() instead of open coding it

Address the following coccicheck warning:

tools/testing/selftests/vm/userfaultfd.c:1536:21-22: WARNING opportunity
for swap().
tools/testing/selftests/vm/userfaultfd.c:1540:33-34: WARNING opportunity
for swap().

by using swap() for the swapping of variable values and drop
`tmp_area` that is not needed any more.

`swap()` macro in userfaultfd.c is introduced in commit 681696862bc18
("selftests: vm: remove dependecy from internal kernel macros")

It has been tested with gcc (Debian 8.3.0-6) 8.3.0.

Link: https://lkml.kernel.org/r/20220407123141.4998-1-guozhengkui@vivo.com
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

selftests/uffd: enable uffd-wp for shmem/hugetlbfs

After we added support for shmem and hugetlbfs, we can turn uffd-wp test
on always now.

Link: https://lkml.kernel.org/r/20220405014932.15212-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm: enable PTE markers by default

Enable PTE markers by default.  On x86_64 it means it'll auto-enable
PTE_MARKER_UFFD_WP as well.

[peterx@redhat.com: hide PTE_MARKER option]
Link: https://lkml.kernel.org/r/20220419202531.27415-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20220405014929.15158-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/uffd: enable write protection for shmem & hugetlbfs

We've had all the necessary changes ready for both shmem and hugetlbfs.
Turn on all the shmem/hugetlbfs switches for userfaultfd-wp.

We can expand UFFD_API_RANGE_IOCTLS_BASIC with _UFFDIO_WRITEPROTECT too
because all existing types now support write protection mode.

Since vma_can_userfault() will be used elsewhere, move into userfaultfd_k.h.

Link: https://lkml.kernel.org/r/20220405014926.15101-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/pagemap: recognize uffd-wp bit for shmem/hugetlbfs

This requires the pagemap code to be able to recognize the newly
introduced swap special pte for uffd-wp, meanwhile the general case for
hugetlb that we recently start to support.  It should make pagemap uffd-wp
support complete.

Link: https://lkml.kernel.org/r/20220405014923.15047-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/khugepaged: don't recycle vma pgtable if uffd-wp registered

When we're trying to collapse a 2M huge shmem page, don't retract pgtable
pmd page if it's registered with uffd-wp, because that pgtable could have
pte markers installed.  Recycling of that pgtable means we'll lose the pte
markers.  That could cause data loss for an uffd-wp enabled application on
shmem.

Instead of disabling khugepaged on these files, simply skip retracting
these special VMAs, then the page cache can still be merged into a huge
thp, and other mm/vma can still map the range of file with a huge thp when
proper.

Note that checking VM_UFFD_WP needs to be done with mmap_sem held for
write, that avoids race like:

         khugepaged                             user thread
         ==========                             ===========
     check VM_UFFD_WP, not set
                                       UFFDIO_REGISTER with uffd-wp on shmem
                                       wr-protect some pages (install markers)
     take mmap_sem write lock
     erase pmd and free pmd page
      --> pte markers are dropped unnoticed!

Link: https://lkml.kernel.org/r/20220405014921.14994-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: handle uffd-wp during fork()

Firstly, we'll need to pass in dst_vma into copy_hugetlb_page_range()
because for uffd-wp it's the dst vma that matters on deciding how we
should treat uffd-wp protected ptes.

We should recognize pte markers during fork and do the pte copy if needed.

[lkp@intel.com: vma_needs_copy can be static]
Link: https://lkml.kernel.org/r/Ylb0CGeFJlc4EzLk@7ec4ff11d4ae
Link: https://lkml.kernel.org/r/20220405014918.14932-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: only drop uffd-wp special pte if required

As with shmem uffd-wp special ptes, only drop the uffd-wp special swap pte
if unmapping an entire vma or synchronized such that faults can not race
with the unmap operation.  This requires passing zap_flags all the way to
the lowest level hugetlb unmap routine: __unmap_hugepage_range.

In general, unmap calls originated in hugetlbfs code will pass the
ZAP_FLAG_DROP_MARKER flag as synchronization is in place to prevent
faults.  The exception is hole punch which will first unmap without any
synchronization.  Later when hole punch actually removes the page from the
file, it will check to see if there was a subsequent fault and if so take
the hugetlb fault mutex while unmapping again.  This second unmap will
pass in ZAP_FLAG_DROP_MARKER.

The justification of "whether to apply ZAP_FLAG_DROP_MARKER flag when
unmap a hugetlb range" is (IMHO): we should never reach a state when a
page fault could errornously fault in a page-cache page that was
wr-protected to be writable, even in an extremely short period.  That
could happen if e.g.  we pass ZAP_FLAG_DROP_MARKER when
hugetlbfs_punch_hole() calls hugetlb_vmdelete_list(), because if a page
faults after that call and before remove_inode_hugepages() is executed,
the page cache can be mapped writable again in the small racy window, that
can cause unexpected data overwritten.

[peterx@redhat.com: fix sparse warning]
Link: https://lkml.kernel.org/r/Ylcdw8I1L5iAoWhb@xz-m1.local
[akpm@linux-foundation.org: move zap_flags_t from mm.h to mm_types.h to fix build issues]
Link: https://lkml.kernel.org/r/20220405014915.14873-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: allow uffd wr-protect none ptes

Teach hugetlbfs code to wr-protect none ptes just in case the page cache
existed for that pte.  Meanwhile we also need to be able to recognize a
uffd-wp marker pte and remove it for uffd_wp_resolve.

Since at it, introduce a variable "psize" to replace all references to the
huge page size fetcher.

Link: https://lkml.kernel.org/r/20220405014912.14815-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: handle pte markers in page faults

Allow hugetlb code to handle pte markers just like none ptes.  It's mostly
there, we just need to make sure we don't assume hugetlb_no_page() only
handles none pte, so when detecting pte change we should use pte_same()
rather than pte_none().  We need to pass in the old_pte to do the
comparison.

Check the original pte to see whether it's a pte marker, if it is, we
should recover uffd-wp bit on the new pte to be installed, so that the
next write will be trapped by uffd.

Link: https://lkml.kernel.org/r/20220405014909.14761-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: handle UFFDIO_WRITEPROTECT

This starts from passing cp_flags into hugetlb_change_protection() so
hugetlb will be able to handle MM_CP_UFFD_WP[_RESOLVE] requests.

huge_pte_clear_uffd_wp() is introduced to handle the case where the
UFFDIO_WRITEPROTECT is requested upon migrating huge page entries.

Link: https://lkml.kernel.org/r/20220405014906.14708-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: take care of UFFDIO_COPY_MODE_WP

Pass the wp_copy variable into hugetlb_mcopy_atomic_pte() thoughout the
stack.  Apply the UFFD_WP bit if UFFDIO_COPY_MODE_WP is with UFFDIO_COPY.

Hugetlb pages are only managed by hugetlbfs, so we're safe even without
setting dirty bit in the huge pte if the page is installed as read-only.
However we'd better still keep the dirty bit set for a read-only
UFFDIO_COPY pte (when UFFDIO_COPY_MODE_WP bit is set), not only to match
what we do with shmem, but also because the page does contain dirty data
that the kernel just copied from the userspace.

Link: https://lkml.kernel.org/r/20220405014904.14643-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb: hook page faults for uffd write protection

Hook up hugetlbfs_fault() with the capability to handle userfaultfd-wp
faults.

We do this slightly earlier than hugetlb_cow() so that we can avoid taking
some extra locks that we definitely don't need.

Link: https://lkml.kernel.org/r/20220405014901.14590-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>