linux-toradex.git/mm/truncate.c, branch v6.18-rc4

Merge tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-06-02T23:00:26+00:00

Pull more MM updates from Andrew Morton:

 - "zram: support algorithm-specific parameters" from Sergey Senozhatsky
   adds infrastructure for passing algorithm-specific parameters into
   zram. A single parameter `winbits' is implemented at this time.

 - "memcg: nmi-safe kmem charging" from Shakeel Butt makes memcg
   charging nmi-safe, which is required by BFP, which can operate in NMI
   context.

 - "Some random fixes and cleanup to shmem" from Kemeng Shi implements
   small fixes and cleanups in the shmem code.

 - "Skip mm selftests instead when kernel features are not present" from
   Zi Yan fixes some issues in the MM selftest code.

 - "mm/damon: build-enable essential DAMON components by default" from
   SeongJae Park reworks DAMON Kconfig to make it easier to enable
   CONFIG_DAMON.

 - "sched/numa: add statistics of numa balance task migration" from Libo
   Chen adds more info into sysfs and procfs files to improve visibility
   into the NUMA balancer's task migration activity.

 - "selftests/mm: cow and gup_longterm cleanups" from Mark Brown
   provides various updates to some of the MM selftests to make them
   play better with the overall containing framework.

* tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (43 commits)
  mm/khugepaged: clean up refcount check using folio_expected_ref_count()
  selftests/mm: fix test result reporting in gup_longterm
  selftests/mm: report unique test names for each cow test
  selftests/mm: add helper for logging test start and results
  selftests/mm: use standard ksft_finished() in cow and gup_longterm
  selftests/damon/_damon_sysfs: skip testcases if CONFIG_DAMON_SYSFS is disabled
  sched/numa: add statistics of numa balance task
  sched/numa: fix task swap by skipping kernel threads
  tools/testing: check correct variable in open_procmap()
  tools/testing/vma: add missing function stub
  mm/gup: update comment explaining why gup_fast() disables IRQs
  selftests/mm: two fixes for the pfnmap test
  mm/khugepaged: fix race with folio split/free using temporary reference
  mm: add CONFIG_PAGE_BLOCK_ORDER to select page block order
  mmu_notifiers: remove leftover stub macros
  selftests/mm: deduplicate test names in madv_populate
  kcov: rust: add flags for KCOV with Rust
  mm: rust: make CONFIG_MMU ifdefs more narrow
  mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables()
  mm/damon/Kconfig: enable CONFIG_DAMON by default
  ...

mm: rename page->index to page->__folio_index

2025-06-01T05:46:06+00:00

All users of page->index have been converted to not refer to it any more. 
Update a few pieces of documentation that were missed and prevent new
users from appearing (or at least make them easy to grep for).

Link: https://lkml.kernel.org/r/20250514181508.3019795-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: David Hildenbrand 
Signed-off-by: Andrew Morton

mm/truncate: fix out-of-bounds when doing a right-aligned split

2025-05-21T05:49:39+00:00

When performing a right split on a folio, the split_at2 may point to a
not-present page if the offset + length equals the original folio size,
which will trigger the following error:

 BUG: unable to handle page fault for address: ffffea0006000008
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 143ffb9067 P4D 143ffb9067 PUD 143ffb8067 PMD 0
 Oops: Oops: 0000 [#1] SMP PTI
 CPU: 0 UID: 0 PID: 502640 Comm: fsx Not tainted 6.15.0-rc3-gc6156189fc6b #889 PR
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/4
 RIP: 0010:truncate_inode_partial_folio+0x208/0x620
 Code: ff 03 48 01 da e8 78 7e 13 00 48 83 05 10 b5 5a 0c 01 85 c0 0f 85 1c 02 001
 RSP: 0018:ffffc90005bafab0 EFLAGS: 00010286
 RAX: 0000000000000000 RBX: ffffea0005ffff00 RCX: 0000000000000002
 RDX: 000000000000000c RSI: 0000000000013975 RDI: ffffc90005bafa30
 RBP: ffffea0006000000 R08: 0000000000000000 R09: 00000000000009bf
 R10: 00000000000007e0 R11: 0000000000000000 R12: 0000000000001633
 R13: 0000000000000000 R14: ffffea0005ffff00 R15: fffffffffffffffe
 FS:  00007f9f9a161740(0000) GS:ffff8894971fd000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffea0006000008 CR3: 000000017c2ae000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  
  truncate_inode_pages_range+0x226/0x720
  truncate_pagecache+0x57/0x90
  ...

Fix this issue by skipping the split if truncation aligns with the folio
size, make sure the split page number lies within the folio.

Link: https://lkml.kernel.org/r/20250512062825.3533342-1-yi.zhang@huaweicloud.com
Fixes: 7460b470a131 ("mm/truncate: use folio_split() in truncate operation")
Signed-off-by: Zhang Yi 
Reviewed-by: Zi Yan 
Cc: ErKun Yang 
Cc: Kefeng Wang 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mm/truncate: use folio_split() in truncate operation

2025-03-18T05:07:00+00:00

Instead of splitting the large folio uniformly during truncation, try to
use buddy allocator like folio_split() at the start and the end of a
truncation range to minimize the number of resulting folios if it is
supported.  try_folio_split() is introduced to use folio_split() if
supported and it falls back to uniform split otherwise.

For example, to truncate a order-4 folio
[0, 1, 2, 3, 4, 5, ..., 15]
between [3, 10] (inclusive), folio_split() splits the folio at 3 to
[0,1], [2], [3], [4..7], [8..15] and [3], [4..7] can be dropped and
[8..15] is kept with zeros in [8..10], then another folio_split() is
done at 10, so [8..10] can be dropped.

One possible optimization is to make folio_split() to split a folio based
on a given range, like [3..10] above.  But that complicates folio_split(),
so it will be investigated when necessary.

Link: https://lkml.kernel.org/r/20250226210032.2044041-8-ziy@nvidia.com
Link: https://lkml.kernel.org/r/20250307174001.242794-8-ziy@nvidia.com
Signed-off-by: Zi Yan 
Cc: Baolin Wang 
Cc: David Hildenbrand 
Cc: Hugh Dickins 
Cc: John Hubbard 
Cc: Kefeng Wang 
Cc: Kirill A. Shuemov 
Cc: Matthew Wilcox 
Cc: Miaohe Lin 
Cc: Ryan Roberts 
Cc: Yang Shi 
Cc: Yu Zhao 
Cc: Kairui Song 
Signed-off-by: Andrew Morton

fs/dax: always remove DAX page-cache entries when breaking layouts

2025-03-18T05:06:37+00:00

Prior to any truncation operations file systems call dax_break_mapping()
to ensure pages in the range are not under going DMA.  Later DAX
page-cache entries will be removed by truncate_folio_batch_exceptionals()
in the generic page-cache code.

However this makes it possible for folios to be removed from the
page-cache even though they are still DMA busy if the file-system hasn't
called dax_break_mapping().  It also means they can never be waited on in
future because FS DAX will lose track of them once the page-cache entry
has been deleted.

Instead it is better to delete the FS DAX entry when the file-system calls
dax_break_mapping() as part of it's truncate operation.  This ensures only
idle pages can be removed from the FS DAX page-cache and makes it easy to
detect if a file-system hasn't called dax_break_mapping() prior to a
truncate operation.

Link: https://lkml.kernel.org/r/3be6115eaaa8d28fee37fcba3287be4f226a7d24.1740713401.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple 
Reviewed-by: Dan Williams 
Tested-by: Alison Schofield 
Cc: Alexander Gordeev 
Cc: Asahi Lina 
Cc: Balbir Singh 
Cc: Bjorn Helgaas 
Cc: Catalin Marinas 
Cc: Christian Borntraeger 
Cc: Christoph Hellwig 
Cc: Chunyan Zhang 
Cc: "Darrick J. Wong" 
Cc: Dave Chinner 
Cc: Dave Hansen 
Cc: Dave Jiang 
Cc: David Hildenbrand 
Cc: Gerald Schaefer 
Cc: Heiko Carstens 
Cc: Huacai Chen 
Cc: Ira Weiny 
Cc: Jan Kara 
Cc: Jason Gunthorpe 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Cc: linmiaohe 
Cc: Logan Gunthorpe 
Cc: Matthew Wilcow (Oracle) 
Cc: Michael "Camp Drill Sergeant" Ellerman 
Cc: Nicholas Piggin 
Cc: Peter Xu 
Cc: Sven Schnelle 
Cc: Ted Ts'o 
Cc: Vasily Gorbik 
Cc: Vishal Verma 
Cc: Vivek Goyal 
Cc: WANG Xuerui 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

mm/truncate: don't skip dirty page in folio_unmap_invalidate()

2025-02-21T13:09:47+00:00

... otherwise this is a behavior change for the previous callers of
invalidate_complete_folio2(), e.g. the page invalidation routine.

Fixes: 4a9e23159fd3 ("mm/truncate: add folio_unmap_invalidate() helper")
Signed-off-by: Jingbo Xu 
Link: https://lore.kernel.org/r/20250218120209.88093-3-jefflexu@linux.alibaba.com
Signed-off-by: Christian Brauner

mm/truncate: add folio_unmap_invalidate() helper

2025-01-26T04:22:43+00:00

Add a folio_unmap_invalidate() helper, which unmaps and invalidates a
given folio.  The caller must already have locked the folio.  Embed the
old invalidate_complete_folio2() helper in there as well, as nobody else
calls it.

Use this new helper in invalidate_inode_pages2_range(), rather than
duplicate the code there.

In preparation for using this elsewhere as well, have it take a gfp_t mask
rather than assume GFP_KERNEL is the right choice.  This bubbles back to
invalidate_complete_folio2() as well.

Link: https://lkml.kernel.org/r/20241220154831.1086649-7-axboe@kernel.dk
Signed-off-by: Jens Axboe 
Cc: Brian Foster 
Cc: Chris Mason 
Cc: Christoph Hellwig 
Cc: Johannes Weiner 
Cc: Kirill A. Shutemov 
Cc: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-11-23T17:58:07+00:00

Pull MM updates from Andrew Morton:

- The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection
algorithm. This leads to improved memory savings.

- Wei Yang has gone to town on the mapletree code, contributing several
series which clean up the implementation:
- "refine mas_mab_cp()"
- "Reduce the space to be cleared for maple_big_node"
- "maple_tree: simplify mas_push_node()"
- "Following cleanup after introduce mas_wr_store_type()"
- "refine storing null"

- The series "selftests/mm: hugetlb_fault_after_madv improvements" from
David Hildenbrand fixes this selftest for s390.

- The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
implements some rationaizations and cleanups in the page mapping
code.

- The series "mm: optimize shadow entries removal" from Shakeel Butt
optimizes the file truncation code by speeding up the handling of
shadow entries.

- The series "Remove PageKsm()" from Matthew Wilcox completes the
migration of this flag over to being a folio-based flag.

- The series "Unify hugetlb into arch_get_unmapped_area functions" from
Oscar Salvador implements a bunch of consolidations and cleanups in
the hugetlb code.

- The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
takes away the wp-fault time practice of turning a huge zero page
into small pages. Instead we replace the whole thing with a THP. More
consistent cleaner and potentiall saves a large number of pagefaults.

- The series "percpu: Add a test case and fix for clang" from Andy
Shevchenko enhances and fixes the kernel's built in percpu test code.

- The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
optimizes mremap() by avoiding doing things which we didn't need to
do.

- The series "Improve the tmpfs large folio read performance" from
Baolin Wang teaches tmpfs to copy data into userspace at the folio
size rather than as individual pages. A 20% speedup was observed.

- The series "mm/damon/vaddr: Fix issue in
damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
splitting.

- The series "memcg-v1: fully deprecate charge moving" from Shakeel
Butt removes the long-deprecated memcgv2 charge moving feature.

- The series "fix error handling in mmap_region() and refactor" from
Lorenzo Stoakes cleanup up some of the mmap() error handling and
addresses some potential performance issues.

- The series "x86/module: use large ROX pages for text allocations"
from Mike Rapoport teaches x86 to use large pages for
read-only-execute module text.

- The series "page allocation tag compression" from Suren Baghdasaryan
is followon maintenance work for the new page allocation profiling
feature.

- The series "page->index removals in mm" from Matthew Wilcox remove
most references to page->index in mm/. A slow march towards shrinking
struct page.

- The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
interface tests" from Andrew Paniakin performs maintenance work for
DAMON's self testing code.

- The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
improves zswap's batching of compression and decompression. It is a
step along the way towards using Intel IAA hardware acceleration for
this zswap operation.

- The series "kasan: migrate the last module test to kunit" from
Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
tests over to the KUnit framework.

- The series "implement lightweight guard pages" from Lorenzo Stoakes
permits userapace to place fault-generating guard pages within a
single VMA, rather than requiring that multiple VMAs be created for
this. Improved efficiencies for userspace memory allocators are
expected.

- The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
tracepoints to provide increased visibility into memcg stats flushing
activity.

- The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
fixes a zram buglet which potentially affected performance.

- The series "mm: add more kernel parameters to control mTHP" from
Maíra Canal enhances our ability to control/configuremultisize THP
from the kernel boot command line.

- The series "kasan: few improvements on kunit tests" from Sabyrzhan
Tasbolatov has a couple of fixups for the KASAN KUnit tests.

- The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
from Kairui Song optimizes list_lru memory utilization when lockdep
is enabled.

* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
mm/kfence: add a new kunit test test_use_after_free_read_nofault()
zram: fix NULL pointer in comp_algorithm_show()
memcg/hugetlb: add hugeTLB counters to memcg
vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
zram: ZRAM_DEF_COMP should depend on ZRAM
MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
Docs/mm/damon: recommend academic papers to read and/or cite
mm: define general function pXd_init()
kmemleak: iommu/iova: fix transient kmemleak false positive
mm/list_lru: simplify the list_lru walk callback function
mm/list_lru: split the lock to per-cgroup scope
mm/list_lru: simplify reparenting and initial allocation
mm/list_lru: code clean up for reparenting
mm/list_lru: don't export list_lru_add
mm/list_lru: don't pass unnecessary key parameters
kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
...

Merge tag 'ext4_for_linus-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2024-11-19T00:32:58+00:00

Pull ext4 updates from Ted Ts'o:
 "A lot of miscellaneous ext4 bug fixes and cleanups this cycle, most
  notably in the journaling code, bufered I/O, and compiler warning
  cleanups"

* tag 'ext4_for_linus-6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (33 commits)
  jbd2: Fix comment describing journal_init_common()
  ext4: prevent an infinite loop in the lazyinit thread
  ext4: use struct_size() to improve ext4_htree_store_dirent()
  ext4: annotate struct fname with __counted_by()
  jbd2: avoid dozens of -Wflex-array-member-not-at-end warnings
  ext4: use str_yes_no() helper function
  ext4: prevent delalloc to nodelalloc on remount
  jbd2: make b_frozen_data allocation always succeed
  ext4: cleanup variable name in ext4_fc_del()
  ext4: use string choices helpers
  jbd2: remove the 'success' parameter from the jbd2_do_replay() function
  jbd2: remove useless 'block_error' variable
  jbd2: factor out jbd2_do_replay()
  jbd2: refactor JBD2_COMMIT_BLOCK process in do_one_pass()
  jbd2: unified release of buffer_head in do_one_pass()
  jbd2: remove redundant judgments for check v1 checksum
  ext4: use ERR_CAST to return an error-valued pointer
  mm: zero range of eof folio exposed by inode size extension
  ext4: partial zero eof block on unaligned inode size extension
  ext4: disambiguate the return value of ext4_dio_write_end_io()
  ...

mm: zero range of eof folio exposed by inode size extension

2024-11-13T04:54:14+00:00

On some filesystems, it is currently possible to create a transient
data inconsistency between pagecache and on-disk state. For example,
on a 1k block size ext4 filesystem:

$ xfs_io -fc "pwrite 0 2k" -c "mmap 0 4k" -c "mwrite 2k 2k" \
	  -c "truncate 8k" -c "fiemap -v" -c "pread -v 2k 16" 
...
 EXT: FILE-OFFSET      BLOCK-RANGE      TOTAL FLAGS
   0: [0..3]:          17410..17413         4   0x1
   1: [4..15]:         hole                12
00000800:  58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58  XXXXXXXXXXXXXXXX
$ umount ; mount  
$ xfs_io -c "pread -v 2k 16" 
00000800:  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................

This allocates and writes two 1k blocks, map writes to the post-eof
portion of the (4k) eof folio, extends the file, and then shows that
the post-eof data is not cleared before the file size is extended.
The result is pagecache with a clean and uptodate folio over a hole
that returns non-zero data. Once reclaimed, pagecache begins to
return valid data.

Some filesystems avoid this problem by flushing the EOF folio before
inode size extension. This triggers writeback time partial post-eof
zeroing. XFS explicitly zeroes newly exposed file ranges via
iomap_zero_range(), but this includes a hack to flush dirty but
hole-backed folios, which means writeback actually does the zeroing
in this particular case as well. bcachefs explicitly flushes the eof
folio on truncate extension to the same effect, but doesn't handle
the analogous write extension case (i.e., replace "truncate 8k" with
"pwrite 4k 4k" in the above example command to reproduce the same
problem on bcachefs). btrfs doesn't seem to support subpage block
sizes.

The two main options to avoid this behavior are to either flush or
do the appropriate zeroing during size extending operations. Zeroing
is only required when the size change exposes ranges of the file
that haven't been directly written, such as a write or truncate that
starts beyond the current eof. The pagecache_isize_extended() helper
is already used for this particular scenario. It currently cleans
any pte's for the eof folio to ensure preexisting mappings fault and
allow the filesystem to take action based on the updated inode size.
This is required to ensure the folio is fully backed by allocated
blocks, for example, but this also happens to be the same scenario
zeroing is required.

Update pagecache_isize_extended() to zero the post-eof range of the
eof folio if it is dirty at the time of the size change, since
writeback now won't have the chance. If non-dirty, the folio has
either not been written or the post-eof portion was zeroed by
writeback.

Signed-off-by: Brian Foster 
Link: https://patch.msgid.link/20240919160741.208162-3-bfoster@redhat.com
Signed-off-by: Theodore Ts'o