commit 96204e1531 upstream.
The addition of commit efa7df3e3b ("mm: align larger anonymous mappings
on THP boundaries") caused the "virtual_address_range" mm selftest to
start failing on arm64. Let's fix that regression.
There were 2 visible problems when running the test; 1) it takes much
longer to execute, and 2) the test fails. Both are related:
The (first part of the) test allocates as many 1GB anonymous blocks as it
can in the low 256TB of address space, passing NULL as the addr hint to
mmap. Before the faulty patch, all allocations were abutted and contained
in a single, merged VMA. However, after this patch, each allocation is in
its own VMA, and there is a 2M gap between each VMA. This causes the 2
problems in the test: 1) mmap becomes MUCH slower because there are so
many VMAs to check to find a new 1G gap. 2) mmap fails once it hits the
VMA limit (/proc/sys/vm/max_map_count). Hitting this limit then causes a
subsequent calloc() to fail, which causes the test to fail.
The problem is that arm64 (unlike x86) selects
ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. But __thp_get_unmapped_area()
allocates len+2M then always aligns to the bottom of the discovered gap.
That causes the 2M hole.
Fix this by detecting cases where we can still achive the alignment goal
when moved to the top of the allocated area, if configured to prefer
top-down allocation.
While we are at it, fix thp_get_unmapped_area's use of pgoff, which should
always be zero for anonymous mappings. Prior to the faulty change, while
it was possible for user space to pass in pgoff!=0, the old
mm->get_unmapped_area() handler would not use it. thp_get_unmapped_area()
does use it, so let's explicitly zero it before calling the handler. This
should also be the correct behavior for arches that define their own
get_unmapped_area() handler.
Link: https://lkml.kernel.org/r/20240123171420.3970220-1-ryan.roberts@arm.com
Fixes: efa7df3e3b ("mm: align larger anonymous mappings on THP boundaries")
Closes: https://lore.kernel.org/linux-mm/1e8f5ac7-54ce-433a-ae53-81522b2320e1@arm.com/
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When running autonuma with enabling multi-size THP, I encountered the
following kernel crash issue:
[ 134.290216] list_del corruption. prev->next should be fffff9ad42e1c490,
but was dead000000000100. (prev=fffff9ad42399890)
[ 134.290877] kernel BUG at lib/list_debug.c:62!
[ 134.291052] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 134.291210] CPU: 56 PID: 8037 Comm: numa01 Kdump: loaded Tainted:
G E 6.7.0-rc4+ #20
[ 134.291649] RIP: 0010:__list_del_entry_valid_or_report+0x97/0xb0
......
[ 134.294252] Call Trace:
[ 134.294362] <TASK>
[ 134.294440] ? die+0x33/0x90
[ 134.294561] ? do_trap+0xe0/0x110
......
[ 134.295681] ? __list_del_entry_valid_or_report+0x97/0xb0
[ 134.295842] folio_undo_large_rmappable+0x99/0x100
[ 134.296003] destroy_large_folio+0x68/0x70
[ 134.296172] migrate_folio_move+0x12e/0x260
[ 134.296264] ? __pfx_remove_migration_pte+0x10/0x10
[ 134.296389] migrate_pages_batch+0x495/0x6b0
[ 134.296523] migrate_pages+0x1d0/0x500
[ 134.296646] ? __pfx_alloc_misplaced_dst_folio+0x10/0x10
[ 134.296799] migrate_misplaced_folio+0x12d/0x2b0
[ 134.296953] do_numa_page+0x1f4/0x570
[ 134.297121] __handle_mm_fault+0x2b0/0x6c0
[ 134.297254] handle_mm_fault+0x107/0x270
[ 134.300897] do_user_addr_fault+0x167/0x680
[ 134.304561] exc_page_fault+0x65/0x140
[ 134.307919] asm_exc_page_fault+0x22/0x30
The reason for the crash is that, the commit 85ce2c517a ("memcontrol:
only transfer the memcg data for migration") removed the charging and
uncharging operations of the migration folios and cleared the memcg data
of the old folio.
During the subsequent release process of the old large folio in
destroy_large_folio(), if the large folio needs to be removed from the
split queue, an incorrect split queue can be obtained (which is
pgdat->deferred_split_queue) because the old folio's memcg is NULL now.
This can lead to list operations being performed under the wrong split
queue lock protection, resulting in a list crash as above.
After the migration, the old folio is going to be freed, so we can remove
it from the split queue in mem_cgroup_migrate() a bit earlier before
clearing the memcg data to avoid getting incorrect split queue.
[akpm@linux-foundation.org: fix comment, per Zi Yan]
Link: https://lkml.kernel.org/r/61273e5e9b490682388377c20f52d19de4a80460.1703054559.git.baolin.wang@linux.alibaba.com
Fixes: 85ce2c517a ("memcontrol: only transfer the memcg data for migration")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
While qualifiying the 6.4 release, the following warning was detected in
messages:
vmstat_refresh: nr_file_hugepages -15664
The warning is caused by the incorrect updating of the NR_FILE_THPS
counter in the function split_huge_page_to_list. The if case is checking
for folio_test_swapbacked, but the else case is missing the check for
folio_test_pmd_mappable. The other functions that manipulate the counter
like __filemap_add_folio and filemap_unaccount_folio have the
corresponding check.
I have a test case, which reproduces the problem. It can be found here:
https://github.com/sroeschus/testcase/blob/main/vmstat_refresh/madv.c
The test case reproduces on an XFS filesystem. Running the same test
case on a BTRFS filesystem does not reproduce the problem.
AFAIK version 6.1 until 6.6 are affected by this problem.
[akpm@linux-foundation.org: whitespace fix]
[shr@devkernel.io: test for folio_test_pmd_mappable()]
Link: https://lkml.kernel.org/r/20231108171517.2436103-1-shr@devkernel.io
Link: https://lkml.kernel.org/r/20231106181918.1091043-1-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Co-debugged-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The 6.0 commits:
commit 9fec51689f ("mm: thp: kill transparent_hugepage_active()")
commit 7da4e2cb8b ("mm: thp: kill __transhuge_page_enabled()")
merged "can we have THPs in this VMA?" logic that was previously done
separately by fault-path, khugepaged, and smaps "THPeligible" checks.
During the process, the semantics of the fault path check changed in two
ways:
1) A VM_NO_KHUGEPAGED check was introduced (also added to smaps path).
2) We no longer checked if non-anonymous memory had a vm_ops->huge_fault
handler that could satisfy the fault. Previously, this check had been
done in create_huge_pud() and create_huge_pmd() routines, but after
the changes, we never reach those routines.
During the review of the above commits, it was determined that in-tree
users weren't affected by the change; most notably, since the only
relevant user (in terms of THP) of VM_MIXEDMAP or ->huge_fault is DAX,
which is explicitly approved early in approval logic. However, this was a
bad assumption to make as it assumes the only reason to support
->huge_fault was for DAX (which is not true in general).
Remove the VM_NO_KHUGEPAGED check when not in collapse path and give any
->huge_fault handler a chance to handle the fault. Note that we don't
validate the file mode or mapping alignment, which is consistent with the
behavior before the aforementioned commits.
Link: https://lkml.kernel.org/r/20230925200110.1979606-1-zokeefe@google.com
Fixes: 7da4e2cb8b ("mm: thp: kill __transhuge_page_enabled()")
Reported-by: Saurabh Singh Sengar <ssengar@microsoft.com>
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()".
Convert page_move_anon_rmap() to folio_move_anon_rmap(), letting the
callers handle PageAnonExclusive. I'm including cleanup patch #3 because
it fits into the picture and can be done cleaner by the conversion.
This patch (of 3):
Let's move it into the caller: there is a difference between whether an
anon folio can only be mapped by one process (e.g., into one VMA), and
whether it is truly exclusive (e.g., no references -- including GUP --
from other processes).
Further, for large folios the page might not actually be pointing at the
head page of the folio, so it better be handled in the caller. This is a
preparation for converting page_move_anon_rmap() to consume a folio.
Link: https://lkml.kernel.org/r/20231002142949.235104-1-david@redhat.com
Link: https://lkml.kernel.org/r/20231002142949.235104-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pull x86 shadow stack support from Dave Hansen:
"This is the long awaited x86 shadow stack support, part of Intel's
Control-flow Enforcement Technology (CET).
CET consists of two related security features: shadow stacks and
indirect branch tracking. This series implements just the shadow stack
part of this feature, and just for userspace.
The main use case for shadow stack is providing protection against
return oriented programming attacks. It works by maintaining a
secondary (shadow) stack using a special memory type that has
protections against modification. When executing a CALL instruction,
the processor pushes the return address to both the normal stack and
to the special permission shadow stack. Upon RET, the processor pops
the shadow stack copy and compares it to the normal stack copy.
For more information, refer to the links below for the earlier
versions of this patch set"
Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/
Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/
* tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
x86/shstk: Change order of __user in type
x86/ibt: Convert IBT selftest to asm
x86/shstk: Don't retry vm_munmap() on -EINTR
x86/kbuild: Fix Documentation/ reference
x86/shstk: Move arch detail comment out of core mm
x86/shstk: Add ARCH_SHSTK_STATUS
x86/shstk: Add ARCH_SHSTK_UNLOCK
x86: Add PTRACE interface for shadow stack
selftests/x86: Add shadow stack test
x86/cpufeatures: Enable CET CR4 bit for shadow stack
x86/shstk: Wire in shadow stack interface
x86: Expose thread features in /proc/$PID/status
x86/shstk: Support WRSS for userspace
x86/shstk: Introduce map_shadow_stack syscall
x86/shstk: Check that signal frame is shadow stack mem
x86/shstk: Check that SSP is aligned on sigreturn
x86/shstk: Handle signals for shadow stack
x86/shstk: Introduce routines modifying shstk
x86/shstk: Handle thread shadow stack
x86/shstk: Add user-mode shadow stack support
...
Pull MM updates from Andrew Morton:
- Some swap cleanups from Ma Wupeng ("fix WARN_ON in
add_to_avail_list")
- Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
reduces the special-case code for handling hugetlb pages in GUP. It
also speeds up GUP handling of transparent hugepages.
- Peng Zhang provides some maple tree speedups ("Optimize the fast path
of mas_store()").
- Sergey Senozhatsky has improved te performance of zsmalloc during
compaction (zsmalloc: small compaction improvements").
- Domenico Cerasuolo has developed additional selftest code for zswap
("selftests: cgroup: add zswap test program").
- xu xin has doe some work on KSM's handling of zero pages. These
changes are mainly to enable the user to better understand the
effectiveness of KSM's treatment of zero pages ("ksm: support
tracking KSM-placed zero-pages").
- Jeff Xu has fixes the behaviour of memfd's
MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").
- David Howells has fixed an fscache optimization ("mm, netfs, fscache:
Stop read optimisation when folio removed from pagecache").
- Axel Rasmussen has given userfaultfd the ability to simulate memory
poisoning ("add UFFDIO_POISON to simulate memory poisoning with
UFFD").
- Miaohe Lin has contributed some routine maintenance work on the
memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
check").
- Peng Zhang has contributed some maintenance work on the maple tree
code ("Improve the validation for maple tree and some cleanup").
- Hugh Dickins has optimized the collapsing of shmem or file pages into
THPs ("mm: free retracted page table by RCU").
- Jiaqi Yan has a patch series which permits us to use the healthy
subpages within a hardware poisoned huge page for general purposes
("Improve hugetlbfs read on HWPOISON hugepages").
- Kemeng Shi has done some maintenance work on the pagetable-check code
("Remove unused parameters in page_table_check").
- More folioification work from Matthew Wilcox ("More filesystem folio
conversions for 6.6"), ("Followup folio conversions for zswap"). And
from ZhangPeng ("Convert several functions in page_io.c to use a
folio").
- page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").
- Baoquan He has converted some architectures to use the
GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert
architectures to take GENERIC_IOREMAP way").
- Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
batched/deferred tlb shootdown during page reclamation/migration").
- Better maple tree lockdep checking from Liam Howlett ("More strict
maple tree lockdep"). Liam also developed some efficiency
improvements ("Reduce preallocations for maple tree").
- Cleanup and optimization to the secondary IOMMU TLB invalidation,
from Alistair Popple ("Invalidate secondary IOMMU TLB on permission
upgrade").
- Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
for arm64").
- Kemeng Shi provides some maintenance work on the compaction code
("Two minor cleanups for compaction").
- Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle
most file-backed faults under the VMA lock").
- Aneesh Kumar contributes code to use the vmemmap optimization for DAX
on ppc64, under some circumstances ("Add support for DAX vmemmap
optimization for ppc64").
- page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
data in page_ext"), ("minor cleanups to page_ext header").
- Some zswap cleanups from Johannes Weiner ("mm: zswap: three
cleanups").
- kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").
- VMA handling cleanups from Kefeng Wang ("mm: convert to
vma_is_initial_heap/stack()").
- DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
address ranges and DAMON monitoring targets").
- Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").
- Liam Howlett has improved the maple tree node replacement code
("maple_tree: Change replacement strategy").
- ZhangPeng has a general code cleanup - use the K() macro more widely
("cleanup with helper macro K()").
- Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for
memmap on memory feature on ppc64").
- pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
in page_alloc"), ("Two minor cleanups for get pageblock
migratetype").
- Vishal Moola introduces a memory descriptor for page table tracking,
"struct ptdesc" ("Split ptdesc from struct page").
- memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
for vm.memfd_noexec").
- MM include file rationalization from Hugh Dickins ("arch: include
asm/cacheflush.h in asm/hugetlb.h").
- THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
output").
- kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
object_cache instead of kmemleak_initialized").
- More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
and _folio_order").
- A VMA locking scalability improvement from Suren Baghdasaryan
("Per-VMA lock support for swap and userfaults").
- pagetable handling cleanups from Matthew Wilcox ("New page table
range API").
- A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
using page->private on tail pages for THP_SWAP + cleanups").
- Cleanups and speedups to the hugetlb fault handling from Matthew
Wilcox ("Change calling convention for ->huge_fault").
- Matthew Wilcox has also done some maintenance work on the MM
subsystem documentation ("Improve mm documentation").
* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits)
maple_tree: shrink struct maple_tree
maple_tree: clean up mas_wr_append()
secretmem: convert page_is_secretmem() to folio_is_secretmem()
nios2: fix flush_dcache_page() for usage from irq context
hugetlb: add documentation for vma_kernel_pagesize()
mm: add orphaned kernel-doc to the rst files.
mm: fix clean_record_shared_mapping_range kernel-doc
mm: fix get_mctgt_type() kernel-doc
mm: fix kernel-doc warning from tlb_flush_rmaps()
mm: remove enum page_entry_size
mm: allow ->huge_fault() to be called without the mmap_lock held
mm: move PMD_ORDER to pgtable.h
mm: remove checks for pte_index
memcg: remove duplication detection for mem_cgroup_uncharge_swap
mm/huge_memory: work on folio->swap instead of page->private when splitting folio
mm/swap: inline folio_set_swap_entry() and folio_swap_entry()
mm/swap: use dedicated entry for swap in folio
mm/swap: stop using page->private on tail pages for THP_SWAP
selftests/mm: fix WARNING comparing pointer to 0
selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check
...
Pull libfs and tmpfs updates from Christian Brauner:
"This cycle saw a lot of work for tmpfs that required changes to the
vfs layer. Andrew, Hugh, and I decided to take tmpfs through vfs this
cycle. Things will go back to mm next cycle.
Features
========
- By far the biggest work is the quota support for tmpfs. New tmpfs
quota infrastructure is added to support it and a new QFMT_SHMEM
uapi option is exposed.
This offers user and group quotas to tmpfs (project quotas will be
added later). Similar to other filesystems tmpfs quota are not
supported within user namespaces yet.
- Add support for user xattrs. While tmpfs already supports security
xattrs (security.*) and POSIX ACLs for a long time it lacked
support for user xattrs (user.*). With this pull request tmpfs will
be able to support a limited number of user xattrs.
This is accompanied by a fix (see below) to limit persistent simple
xattr allocations.
- Add support for stable directory offsets. Currently tmpfs relies on
the libfs provided cursor-based mechanism for readdir. This causes
issues when a tmpfs filesystem is exported via NFS.
NFS clients do not open directories. Instead, each server-side
readdir operation opens the directory, reads it, and then closes
it. Since the cursor state for that directory is associated with
the opened file it is discarded after each readdir operation. Such
directory offsets are not just cached by NFS clients but also
various userspace libraries based on these clients.
As it stands there is no way to invalidate the caches when
directory offsets have changed and the whole application depends on
unchanging directory offsets.
At LSFMM we discussed how to solve this problem and decided to
support stable directory offsets. libfs now allows filesystems like
tmpfs to use an xarrary to map a directory offset to a dentry. This
mechanism is currently only used by tmpfs but can be supported by
others as well.
Fixes
=====
- Change persistent simple xattrs allocations in libfs from
GFP_KERNEL to GPF_KERNEL_ACCOUNT so they're subject to memory
cgroup limits. Since this is a change to libfs it affects both
tmpfs and kernfs.
- Correctly verify {g,u}id mount options.
A new filesystem context is created via fsopen() which records the
namespace that becomes the owning namespace of the superblock when
fsconfig(FSCONFIG_CMD_CREATE) is called for filesystems that are
mountable in namespaces. However, fsconfig() calls can occur in a
namespace different from the namespace where fsopen() has been
called.
Currently, when fsconfig() is called to set {g,u}id mount options
the requested {g,u}id is mapped into a k{g,u}id according to the
namespace where fsconfig() was called from. The resulting k{g,u}id
is not guaranteed to be resolvable in the namespace of the
filesystem (the one that fsopen() was called in).
This means it's possible for an unprivileged user to create files
owned by any group in a tmpfs mount since it's possible to set the
setid bits on the tmpfs directory.
The contract for {g,u}id mount options and {g,u}id values in
general set from userspace has always been that they are translated
according to the caller's idmapping. In so far, tmpfs has been
doing the correct thing. But since tmpfs is mountable in
unprivileged contexts it is also necessary to verify that the
resulting {k,g}uid is representable in the namespace of the
superblock to avoid such bugs.
The new mount api's cross-namespace delegation abilities are
already widely used. Having talked to a bunch of userspace this is
the most faithful solution with minimal regression risks"
* tag 'v6.6-vfs.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
tmpfs,xattr: GFP_KERNEL_ACCOUNT for simple xattrs
mm: invalidation check mapping before folio_contains
tmpfs: trivial support for direct IO
tmpfs,xattr: enable limited user extended attributes
tmpfs: track free_ispace instead of free_inodes
xattr: simple_xattr_set() return old_xattr to be freed
tmpfs: verify {g,u}id mount options correctly
shmem: move spinlock into shmem_recalc_inode() to fix quota support
libfs: Remove parent dentry locking in offset_iterate_dir()
libfs: Add a lock class for the offset map's xa_lock
shmem: stable directory offsets
shmem: Refactor shmem_symlink()
libfs: Add directory operations for stable offsets
shmem: fix quota lock nesting in huge hole handling
shmem: Add default quota limit mount options
shmem: quota support
shmem: prepare shmem quota infrastructure
quota: Check presence of quota operation structures instead of ->quota_read and ->quota_write callbacks
shmem: make shmem_get_inode() return ERR_PTR instead of NULL
shmem: make shmem_inode_acct_block() return error
Commit fc986a38b6 ("mm: huge_memory: convert madvise_free_huge_pmd to
use a folio") replaced the page_mapcount() with folio_mapcount() to check
whether the folio is shared by other mapping.
It's not correct for large folios. folio_mapcount() returns the total
mapcount of large folio which is not suitable to detect whether the folio
is shared.
Use folio_estimated_sharers() which returns a estimated number of shares.
That means it's not 100% correct. It should be OK for madvise case here.
User-visible effects is that the THP is skipped when user call madvise.
But the correct behavior is THP should be split and processed then.
NOTE: this change is a temporary fix to reduce the user-visible effects
before the long term fix from David is ready.
Link: https://lkml.kernel.org/r/20230808020917.2230692-3-fengwei.yin@intel.com
Fixes: fc986a38b6 ("mm: huge_memory: convert madvise_free_huge_pmd to use a folio")
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Unfortunately commit 474098edac ("mm/gup: replace FOLL_NUMA by
gup_can_follow_protnone()") missed that follow_page() and
follow_trans_huge_pmd() never implicitly set FOLL_NUMA because they really
don't want to fail on PROT_NONE-mapped pages -- either due to NUMA hinting
or due to inaccessible (PROT_NONE) VMAs.
As spelled out in commit 0b9d705297 ("mm: numa: Support NUMA hinting
page faults from gup/gup_fast"): "Other follow_page callers like KSM
should not use FOLL_NUMA, or they would fail to get the pages if they use
follow_page instead of get_user_pages."
liubo reported [1] that smaps_rollup results are imprecise, because they
miss accounting of pages that are mapped PROT_NONE. Further, it's easy to
reproduce that KSM no longer works on inaccessible VMAs on x86-64, because
pte_protnone()/pmd_protnone() also indictaes "true" in inaccessible VMAs,
and follow_page() refuses to return such pages right now.
As KVM really depends on these NUMA hinting faults, removing the
pte_protnone()/pmd_protnone() handling in GUP code completely is not
really an option.
To fix the issues at hand, let's revive FOLL_NUMA as FOLL_HONOR_NUMA_FAULT
to restore the original behavior for now and add better comments.
Set FOLL_HONOR_NUMA_FAULT independent of FOLL_FORCE in
is_valid_gup_args(), to add that flag for all external GUP users.
Note that there are three GUP-internal __get_user_pages() users that don't
end up calling is_valid_gup_args() and consequently won't get
FOLL_HONOR_NUMA_FAULT set.
1) get_dump_page(): we really don't want to handle NUMA hinting
faults. It specifies FOLL_FORCE and wouldn't have honored NUMA
hinting faults already.
2) populate_vma_page_range(): we really don't want to handle NUMA hinting
faults. It specifies FOLL_FORCE on accessible VMAs, so it wouldn't have
honored NUMA hinting faults already.
3) faultin_vma_page_range(): we similarly don't want to handle NUMA
hinting faults.
To make the combination of FOLL_FORCE and FOLL_HONOR_NUMA_FAULT work in
inaccessible VMAs properly, we have to perform VMA accessibility checks in
gup_can_follow_protnone().
As GUP-fast should reject such pages either way in
pte_access_permitted()/pmd_access_permitted() -- for example on x86-64 and
arm64 that both implement pte_protnone() -- let's just always fallback to
ordinary GUP when stumbling over pte_protnone()/pmd_protnone().
As Linus notes [2], honoring NUMA faults might only make sense for
selected GUP users.
So we should really see if we can instead let relevant GUP callers specify
it manually, and not trigger NUMA hinting faults from GUP as default.
Prepare for that by making FOLL_HONOR_NUMA_FAULT an external GUP flag and
adding appropriate documenation.
While at it, remove a stale comment from follow_trans_huge_pmd(): That
comment for pmd_protnone() was added in commit 2b4847e730 ("mm: numa:
serialise parallel get_user_page against THP migration"), which noted:
THP does not unmap pages due to a lack of support for migration
entries at a PMD level. This allows races with get_user_pages
Nowadays, we do have PMD migration entries, so the comment no longer
applies. Let's drop it.
[1] https://lore.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com
[2] https://lore.kernel.org/r/CAHk-=wgRiP_9X0rRdZKT8nhemZGNateMtb366t37d8-x7VRs=g@mail.gmail.com
Link: https://lkml.kernel.org/r/20230803143208.383663-2-david@redhat.com
Fixes: 474098edac ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: liubo <liubo254@huawei.com>
Closes: https://lore.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com
Reported-by: Peter Xu <peterx@redhat.com>
Closes: https://lore.kernel.org/all/ZMKJjDaqZ7FW0jfe@x1n/
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm, netfs, fscache: Stop read optimisation when folio
removed from pagecache", v7.
This fixes an optimisation in fscache whereby we don't read from the cache
for a particular file until we know that there's data there that we don't
have in the pagecache. The problem is that I'm no longer using PG_fscache
(aka PG_private_2) to indicate that the page is cached and so I don't get
a notification when a cached page is dropped from the pagecache.
The first patch merges some folio_has_private() and
filemap_release_folio() pairs and introduces a helper,
folio_needs_release(), to indicate if a release is required.
The second patch is the actual fix. Following Willy's suggestions[1], it
adds an AS_RELEASE_ALWAYS flag to an address_space that will make
filemap_release_folio() always call ->release_folio(), even if
PG_private/PG_private_2 aren't set. folio_needs_release() is altered to
add a check for this.
This patch (of 2):
Make filemap_release_folio() check folio_has_private(). Then, in most
cases, where a call to folio_has_private() is immediately followed by a
call to filemap_release_folio(), we can get rid of the test in the pair.
There are a couple of sites in mm/vscan.c that this can't so easily be
done. In shrink_folio_list(), there are actually three cases (something
different is done for incompletely invalidated buffers), but
filemap_release_folio() elides two of them.
In shrink_active_list(), we don't have have the folio lock yet, so the
check allows us to avoid locking the page unnecessarily.
A wrapper function to check if a folio needs release is provided for those
places that still need to do it in the mm/ directory. This will acquire
additional parts to the condition in a future patch.
After this, the only remaining caller of folio_has_private() outside of
mm/ is a check in fuse.
Link: https://lkml.kernel.org/r/20230628104852.3391651-1-dhowells@redhat.com
Link: https://lkml.kernel.org/r/20230628104852.3391651-2-dhowells@redhat.com
Reported-by: Rohith Surabattula <rohiths.msft@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steve French <sfrench@samba.org>
Cc: Shyam Prasad N <nspmangalore@gmail.com>
Cc: Rohith Surabattula <rohiths.msft@gmail.com>
Cc: Dave Wysochanski <dwysocha@redhat.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Xiubo Li <xiubli@redhat.com>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
i_pages lock nests inside i_lock, but shmem_charge() and shmem_uncharge()
were being called from THP splitting or collapsing while i_pages lock was
held, and now go on to call dquot_alloc_block_nodirty() which takes
i_lock to update i_blocks.
We may well want to take i_lock out of this path later, in the non-quota
case even if it's left in the quota case (or perhaps use i_lock instead
of shmem's info->lock throughout); but don't get into that at this time.
Move the shmem_charge() and shmem_uncharge() calls out from under i_pages
lock, accounting the full batch of holes in a single call.
Still pass the pages argument to shmem_uncharge(), but it happens now to
be unused: shmem_recalc_inode() is designed to account for clean pages
freed behind shmem's back, so it gets the accounting right by itself;
then the later call to shmem_inode_unacct_blocks() led to imbalance
(that WARN_ON(inode->i_blocks) in shmem_evict_inode()).
Reported-by: syzbot+38ca19393fb3344f57e6@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/0000000000008e62f40600bfe080@google.com/
Reported-by: syzbot+440ff8cca06ee7a1d4db@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/00000000000076a7840600bfb6e8@google.com/
Signed-off-by: Hugh Dickins <hughd@google.com>
Tested-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Message-Id: <20230725144510.253763-8-cem@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The x86 Control-flow Enforcement Technology (CET) feature includes a new
type of memory called shadow stack. This shadow stack memory has some
unusual properties, which requires some core mm changes to function
properly.
One sharp edge is that PTEs that are both Write=0 and Dirty=1 are
treated as shadow by the CPU, but this combination used to be created by
the kernel on x86. Previous patches have changed the kernel to now avoid
creating these PTEs unless they are for shadow stack memory. In case any
missed corners of the kernel are still creating PTEs like this for
non-shadow stack memory, and to catch any re-introductions of the logic,
warn if any shadow stack PTEs (Write=0, Dirty=1) are found in non-shadow
stack VMAs when they are being zapped. This won't catch transient cases
but should have decent coverage.
In order to check if a PTE is shadow stack in core mm code, add two arch
breakouts arch_check_zapped_pte/pmd(). This will allow shadow stack
specific code to be kept in arch/x86.
Only do the check if shadow stack is supported by the CPU and configured
because in rare cases older CPUs may write Dirty=1 to a Write=0 CPU on
older CPUs. This check is handled in pte_shstk()/pmd_shstk().
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/20230613001108.3040476-18-rick.p.edgecombe%40intel.com
The x86 Shadow stack feature includes a new type of memory called shadow
stack. This shadow stack memory has some unusual properties, which requires
some core mm changes to function properly.
One of these unusual properties is that shadow stack memory is writable,
but only in limited ways. These limits are applied via a specific PTE
bit combination. Nevertheless, the memory is writable, and core mm code
will need to apply the writable permissions in the typical paths that
call pte_mkwrite(). Future patches will make pte_mkwrite() take a VMA, so
that the x86 implementation of it can know whether to create regular
writable or shadow stack mappings.
But there are a couple of challenges to this. Modifying the signatures of
each arch pte_mkwrite() implementation would be error prone because some
are generated with macros and would need to be re-implemented. Also, some
pte_mkwrite() callers operate on kernel memory without a VMA.
So this can be done in a three step process. First pte_mkwrite() can be
renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite()
added that just calls pte_mkwrite_novma(). Next callers without a VMA can
be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers
can be changed to take/pass a VMA.
Previous work pte_mkwrite() renamed pte_mkwrite_novma() and converted
callers that don't have a VMA were to use pte_mkwrite_novma(). So now
change pte_mkwrite() to take a VMA and change the remaining callers to
pass a VMA. Apply the same changes for pmd_mkwrite().
No functional change.
Suggested-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/all/20230613001108.3040476-4-rick.p.edgecombe%40intel.com
free_transhuge_page() acquires split queue lock then check whether the THP
was added to deferred list or not. It brings high deferred queue lock
contention.
It's safe to check whether the THP is in deferred list or not without
holding the deferred queue lock in free_transhuge_page() because when code
hit free_transhuge_page(), there is no one tries to add the folio to
_deferred_list.
Running page_fault1 of will-it-scale + order 2 folio for anonymous
mapping with 96 processes on an Ice Lake 48C/96T test box, we could
see the 61% split_queue_lock contention:
- 63.02% 0.01% page_fault1_pro [kernel.kallsyms] [k] free_transhuge_page
- 63.01% free_transhuge_page
+ 62.91% _raw_spin_lock_irqsave
With this patch applied, the split_queue_lock contention is less
than 1%.
Link: https://lkml.kernel.org/r/20230429082759.1600796-2-fengwei.yin@intel.com
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Staring at the comment "Recheck VMA as permissions can change since
migration started" in remove_migration_pte() can result in confusion,
because if the source PTE/PMD indicates write permissions, then there
should be no need to check VMA write permissions when restoring migration
entries or PTE-mapping a PMD.
Commit d3cb8bf608 ("mm: migrate: Close race between migration completion
and mprotect") introduced the maybe_mkwrite() handling in
remove_migration_pte() in 2014, stating that a race between mprotect() and
migration finishing would be possible, and that we could end up with a
writable PTE that should be readable.
However, mprotect() code first updates vma->vm_flags / vma->vm_page_prot
and then walks the page tables to (a) set all present writable PTEs to
read-only and (b) convert all writable migration entries to readable
migration entries. While walking the page tables and modifying the
entries, migration code has to grab the PT locks to synchronize against
concurrent page table modifications.
Assuming migration would find a writable migration entry (while holding
the PT lock) and replace it with a writable present PTE, surely mprotect()
code didn't stumble over the writable migration entry yet (converting it
into a readable migration entry) and would instead wait for the PT lock to
convert the now present writable PTE into a read-only PTE. As mprotect()
didn't finish yet, the behavior is just like migration didn't happen: a
writable PTE will be converted to a read-only PTE.
So it's fine to rely on the writability information in the source PTE/PMD
and not recheck against the VMA as long as we're holding the PT lock to
synchronize with anyone who concurrently wants to downgrade write
permissions (like mprotect()) by first adjusting vma->vm_flags /
vma->vm_page_prot to then walk over the page tables to adjust the page
table entries.
Running test cases that should reveal such races -- mprotect(PROT_READ)
racing with page migration or THP splitting -- for multiple hours did not
reveal an issue with this cleanup.
Link: https://lkml.kernel.org/r/20230418142113.439494-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
No need to call maybe_mkwrite() to then wrprotect if the source PMD was not
writable.
It's worth nothing that this now allows for PTEs to be writable even if
the source PMD was not writable: if vma->vm_page_prot includes write
permissions.
As documented in commit 931298e103 ("mm/userfaultfd: rely on
vma->vm_page_prot in uffd_wp_range()"), any mechanism that intends to
have pages wrprotected (COW, writenotify, mprotect, uffd-wp, softdirty,
...) has to properly adjust vma->vm_page_prot upfront, to not include
write permissions. If vma->vm_page_prot includes write permissions, the
PTE/PMD can be writable as default.
This now mimics the handling in mm/migrate.c:remove_migration_pte() and in
mm/huge_memory.c:remove_migration_pmd(), which has been in place for a
long time (except that 96a9c287e2 ("mm/migrate: fix wrongly apply write
bit after mkdirty on sparc64") temporarily changed it).
Link: https://lkml.kernel.org/r/20230411142512.438404-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If we end up with a writable migration entry that has the uffd-wp bit set,
we already messed up: the source PTE/PMD was writable, which means we
could have modified the page without notifying uffd first. Setting the
uffd-wp bit always implies converting migration entries to !writable
migration entries.
Commit 8f34f1eac3 ("mm/userfaultfd: fix uffd-wp special cases for
fork()") documents that "3. Forget to carry over uffd-wp bit for a write
migration huge pmd entry", but it doesn't really say why that should be
relevant.
So let's remove that code to avoid hiding an eventual underlying issue (in
the future, we might want to warn when creating writable migration entries
that have the uffd-wp bit set -- or even better when turning a PTE
writable that still has the uffd-wp bit set).
This now matches the handling for hugetlb migration entries in
hugetlb_change_protection().
In copy_huge_pmd()/copy_nonpresent_pte()/copy_hugetlb_page_range(), we
still transfer the uffd-bit also for writable migration entries, but
simply because we have unified handling for "writable" and
"readable-exclusive" migration entries, and we care about transferring the
uffd-wp bit for the latter.
Link: https://lkml.kernel.org/r/20230405160236.587705-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Looks like what we fixed for hugetlb in commit 44f86392bd ("mm/hugetlb:
fix uffd-wp handling for migration entries in
hugetlb_change_protection()") similarly applies to THP.
Setting/clearing uffd-wp on THP migration entries is not implemented
properly. Further, while removing migration PMDs considers the uffd-wp
bit, inserting migration PMDs does not consider the uffd-wp bit.
We have to set/clear independently of the migration entry type in
change_huge_pmd() and properly copy the uffd-wp bit in
set_pmd_migration_entry().
Verified using a simple reproducer that triggers migration of a THP, that
the set_pmd_migration_entry() no longer loses the uffd-wp bit.
Link: https://lkml.kernel.org/r/20230405160236.587705-2-david@redhat.com
Fixes: f45ec5ff16 ("userfaultfd: wp: support swap and page migration")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
