linux.git/mm/huge_memory.c, branch v6.14

mm/huge_memory: drop beyond-EOF folios with the right number of refs

2025-03-17T00:40:25+00:00

When an after-split folio is large and needs to be dropped due to EOF,
folio_put_refs(folio, folio_nr_pages(folio)) should be used to drop all
page cache refs.  Otherwise, the folio will not be freed, causing memory
leak.

This leak would happen on a filesystem with blocksize > page_size and a
truncate is performed, where the blocksize makes folios split to >0 order
ones, causing truncated folios not being freed.

Link: https://lkml.kernel.org/r/20250310155727.472846-1-ziy@nvidia.com
Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages")
Signed-off-by: Zi Yan 
Reported-by: Hugh Dickins 
Closes: https://lore.kernel.org/all/fcbadb7f-dd3e-21df-f9a7-2853b53183c4@google.com/
Cc: Baolin Wang 
Cc: David Hildenbrand 
Cc: John Hubbard 
Cc: Kefeng Wang 
Cc: Kirill A. Shuemov 
Cc: Luis Chamberalin 
Cc: Matthew Wilcow (Oracle) 
Cc: Miaohe Lin 
Cc: Pankaj Raghav 
Cc: Ryan Roberts 
Cc: Yang Shi 
Cc: Yu Zhao 
Cc: 
Signed-off-by: Andrew Morton

mm/huge_memory: convert has_hwpoisoned into a pure folio flag

2025-01-26T04:22:41+00:00

Patch series "mm: hugetlb+THP folio and migration cleanups", v2.

Some cleanups around more folio conversion and migration handling that I
collected working on random stuff.


This patch (of 6):

Let's stop setting it on pages, there is no need to anymore.

Link: https://lkml.kernel.org/r/20250113131611.2554758-2-david@redhat.com
Signed-off-by: David Hildenbrand 
Reviewed-by: Matthew Wilcox (Oracle) 
Cc: Muchun Song 
Cc: Baolin Wang 
Cc: Sidhartha Kumar 
Signed-off-by: Andrew Morton

mm/huge_memory.c: rename shadowed local

2025-01-26T04:22:18+00:00

split_huge_pages_write() has a lccal `buf' which shadows incoming arg
`buf'.  Reviewer confusion resulted.  Rename the inner local to `tok_buf'.

Cc: Leo Stone 
Signed-off-by: Andrew Morton

mm: add per-order mTHP swap-in fallback/fallback_charge counters

2025-01-14T06:40:49+00:00

Currently, large folio swap-in is supported, but we lack a method to
analyze their success ratio.  Similar to anon_fault_fallback, we introduce
per-order mTHP swpin_fallback and swpin_fallback_charge counters for
calculating their success ratio.  The new counters are located at:

/sys/kernel/mm/transparent_hugepage/hugepages-/stats/
	swpin_fallback
	swpin_fallback_charge

Link: https://lkml.kernel.org/r/20241202124730.2407037-1-haowenchao22@gmail.com
Signed-off-by: Wenchao Hao 
Reviewed-by: Barry Song 
Reviewed-by: Lance Yang 
Cc: Baolin Wang 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Matthew Wilcox 
Cc: Peter Xu 
Cc: Ryan Roberts 
Cc: Usama Arif 
Signed-off-by: Andrew Morton

mm: migrate: remove unused argument vma from migrate_misplaced_folio()

2025-01-14T06:40:30+00:00

Commit ee86814b0562 ("mm/migrate: move NUMA hinting fault folio isolation
+ checks under PTL") removed the code that had used the vma argument in
migrate_misplaced_folio.

Since the vma argument was no longer used in migrate_misplaced_folio, this
patch removes it.

Link: https://lkml.kernel.org/r/20241126155655.466186-1-donettom@linux.ibm.com
Signed-off-by: Donet Tom 
Reviewed-by: Baolin Wang 
Reviewed-by: Zi Yan 
Acked-by: David Hildenbrand 
Cc: Ritesh Harjani (IBM) 
Signed-off-by: Andrew Morton

mm: clear uffd-wp PTE/PMD state on mremap()

2025-01-13T03:03:37+00:00

When mremap()ing a memory region previously registered with userfaultfd as
write-protected but without UFFD_FEATURE_EVENT_REMAP, an inconsistency in
flag clearing leads to a mismatch between the vma flags (which have
uffd-wp cleared) and the pte/pmd flags (which do not have uffd-wp
cleared).  This mismatch causes a subsequent mprotect(PROT_WRITE) to
trigger a warning in page_table_check_pte_flags() due to setting the pte
to writable while uffd-wp is still set.

Fix this by always explicitly clearing the uffd-wp pte/pmd flags on any
such mremap() so that the values are consistent with the existing clearing
of VM_UFFD_WP.  Be careful to clear the logical flag regardless of its
physical form; a PTE bit, a swap PTE bit, or a PTE marker.  Cover PTE,
huge PMD and hugetlb paths.

Link: https://lkml.kernel.org/r/20250107144755.1871363-2-ryan.roberts@arm.com
Co-developed-by: Mikołaj Lenczewski 
Signed-off-by: Mikołaj Lenczewski 
Signed-off-by: Ryan Roberts 
Closes: https://lore.kernel.org/linux-mm/810b44a8-d2ae-4107-b665-5a42eae2d948@arm.com/
Fixes: 63b2d4174c4a ("userfaultfd: wp: add the writeprotect API to userfaultfd ioctl")
Cc: David Hildenbrand 
Cc: Jann Horn 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: Mark Rutland 
Cc: Muchun Song 
Cc: Peter Xu 
Cc: Shuah Khan 
Cc: Vlastimil Babka 
Cc: 
Signed-off-by: Andrew Morton

mm: huge_memory: handle strsep not finding delimiter

2024-12-19T03:04:47+00:00

split_huge_pages_write() does not handle the case where strsep finds no
delimiter in the given string and sets the input buffer to NULL, which
allows this reproducer to trigger a protection fault.

Link: https://lkml.kernel.org/r/20241216042752.257090-2-leocstone@gmail.com
Signed-off-by: Leo Stone 
Reported-by: syzbot+8a3da2f1bbf59227c289@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8a3da2f1bbf59227c289
Signed-off-by: Andrew Morton

mm: convert partially_mapped set/clear operations to be atomic

2024-12-19T03:04:45+00:00

Other page flags in the 2nd page, like PG_hwpoison and PG_anon_exclusive
can get modified concurrently.  Changes to other page flags might be lost
if they are happening at the same time as non-atomic partially_mapped
operations.  Hence, make partially_mapped operations atomic.

Link: https://lkml.kernel.org/r/20241212183351.1345389-1-usamaarif642@gmail.com
Fixes: 8422acdc97ed ("mm: introduce a pageflag for partially mapped folios")
Reported-by: David Hildenbrand 
Link: https://lore.kernel.org/all/e53b04ad-1827-43a2-a1ab-864c7efecf6e@redhat.com/
Signed-off-by: Usama Arif 
Acked-by: David Hildenbrand 
Acked-by: Johannes Weiner 
Acked-by: Roman Gushchin 
Cc: Barry Song 
Cc: Domenico Cerasuolo 
Cc: Jonathan Corbet 
Cc: Matthew Wilcox 
Cc: Mike Rapoport (Microsoft) 
Cc: Nico Pache 
Cc: Rik van Riel 
Cc: Ryan Roberts 
Cc: Shakeel Butt 
Cc: Yu Zhao 
Cc: 
Signed-off-by: Andrew Morton

mm: use clear_user_(high)page() for arch with special user folio handling

2024-12-19T03:04:43+00:00

Some architectures have special handling after clearing user folios:
architectures, which set cpu_dcache_is_aliasing() to true, require
flushing dcache; arc, which sets cpu_icache_is_aliasing() to true, changes
folio->flags to make icache coherent to dcache.  So __GFP_ZERO using only
clear_page() is not enough to zero user folios and clear_user_(high)page()
must be used.  Otherwise, user data will be corrupted.

Fix it by always clearing user folios with clear_user_(high)page() when
cpu_dcache_is_aliasing() is true or cpu_icache_is_aliasing() is true. 
Rename alloc_zeroed() to user_alloc_needs_zeroing() and invert the logic
to clarify its intend.

Link: https://lkml.kernel.org/r/20241209182326.2955963-2-ziy@nvidia.com
Fixes: 5708d96da20b ("mm: avoid zeroing user movable page twice with init_on_alloc=1")
Signed-off-by: Zi Yan 
Reported-by: Geert Uytterhoeven 
Closes: https://lore.kernel.org/linux-mm/CAMuHMdV1hRp_NtR5YnJo=HsfgKQeH91J537Gh4gKk3PFZhSkbA@mail.gmail.com/
Tested-by: Geert Uytterhoeven 
Acked-by: Vlastimil Babka 
Cc: Alexander Potapenko 
Cc: David Hildenbrand 
Cc: John Hubbard 
Cc: Kees Cook 
Cc: Kefeng Wang 
Cc: Mathieu Desnoyers 
Cc: Matthew Wilcox 
Cc: Miaohe Lin 
Cc: Ryan Roberts 
Cc: Vineet Gupta 
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
...