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171 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Hugh Dickins
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be5ef2d9b0 |
mm,thp,rmap: subpages_mapcount of PTE-mapped subpages
Patch series "mm,thp,rmap: rework the use of subpages_mapcount", v2. This patch (of 3): Following suggestion from Linus, instead of counting every PTE map of a compound page in subpages_mapcount, just count how many of its subpages are PTE-mapped: this yields the exact number needed for NR_ANON_MAPPED and NR_FILE_MAPPED stats, without any need for a locked scan of subpages; and requires updating the count less often. This does then revert total_mapcount() and folio_mapcount() to needing a scan of subpages; but they are inherently racy, and need no locking, so Linus is right that the scans are much better done there. Plus (unlike in 6.1 and previous) subpages_mapcount lets us avoid the scan in the common case of no PTE maps. And page_mapped() and folio_mapped() remain scanless and just as efficient with the new meaning of subpages_mapcount: those are the functions which I most wanted to remove the scan from. The updated page_dup_compound_rmap() is no longer suitable for use by anon THP's __split_huge_pmd_locked(); but page_add_anon_rmap() can be used for that, so long as its VM_BUG_ON_PAGE(!PageLocked) is deleted. Evidence is that this way goes slightly faster than the previous implementation for most cases; but significantly faster in the (now scanless) pmds after ptes case, which started out at 870ms and was brought down to 495ms by the previous series, now takes around 105ms. Link: https://lkml.kernel.org/r/a5849eca-22f1-3517-bf29-95d982242742@google.com Link: https://lkml.kernel.org/r/eec17e16-4e1-7c59-f1bc-5bca90dac919@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dan Carpenter <error27@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: James Houghton <jthoughton@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Peter Xu <peterx@redhat.com> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Hugh Dickins
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9bd3155ed8 |
mm,thp,rmap: lock_compound_mapcounts() on THP mapcounts
Fix the races in maintaining compound_mapcount, subpages_mapcount and
subpage _mapcount by using PG_locked in the first tail of any compound
page for a bit_spin_lock() on such modifications; skipping the usual
atomic operations on those fields in this case.
Bring page_remove_file_rmap() and page_remove_anon_compound_rmap() back
into page_remove_rmap() itself. Rearrange page_add_anon_rmap() and
page_add_file_rmap() and page_remove_rmap() to follow the same "if
(compound) {lock} else if (PageCompound) {lock} else {atomic}" pattern
(with a PageTransHuge in the compound test, like before, to avoid BUG_ONs
and optimize away that block when THP is not configured). Move all the
stats updates outside, after the bit_spin_locked section, so that it is
sure to be a leaf lock.
Add page_dup_compound_rmap() to manage compound locking versus atomics in
sync with the rest. In particular, hugetlb pages are still using the
atomics: to avoid unnecessary interference there, and because they never
have subpage mappings; but this exception can easily be changed.
Conveniently, page_dup_compound_rmap() turns out to suit an anon THP's
__split_huge_pmd_locked() too.
bit_spin_lock() is not popular with PREEMPT_RT folks: but PREEMPT_RT
sensibly excludes TRANSPARENT_HUGEPAGE already, so its only exposure is to
the non-hugetlb non-THP pte-mapped compound pages (with large folios being
currently dependent on TRANSPARENT_HUGEPAGE). There is never any scan of
subpages in this case; but we have chosen to use PageCompound tests rather
than PageTransCompound tests to gate the use of lock_compound_mapcounts(),
so that page_mapped() is correct on all compound pages, whether or not
TRANSPARENT_HUGEPAGE is enabled: could that be a problem for PREEMPT_RT,
when there is contention on the lock - under heavy concurrent forking for
example? If so, then it can be turned into a sleeping lock (like
folio_lock()) when PREEMPT_RT.
A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took
18 seconds on small pages, and used to take 1 second on huge pages, but
now takes 115 milliseconds on huge pages. Mapping by pmds a second time
used to take 860ms and now takes 86ms; mapping by pmds after mapping by
ptes (when the scan is needed) used to take 870ms and now takes 495ms.
Mapping huge pages by ptes is largely unaffected but variable: between 5%
faster and 5% slower in what I've recorded. Contention on the lock is
likely to behave worse than contention on the atomics behaved.
Link: https://lkml.kernel.org/r/1b42bd1a-8223-e827-602f-d466c2db7d3c@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Hugh Dickins
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cb67f4282b |
mm,thp,rmap: simplify compound page mapcount handling
Compound page (folio) mapcount calculations have been different for anon and file (or shmem) THPs, and involved the obscure PageDoubleMap flag. And each huge mapping and unmapping of a file (or shmem) THP involved atomically incrementing and decrementing the mapcount of every subpage of that huge page, dirtying many struct page cachelines. Add subpages_mapcount field to the struct folio and first tail page, so that the total of subpage mapcounts is available in one place near the head: then page_mapcount() and total_mapcount() and page_mapped(), and their folio equivalents, are so quick that anon and file and hugetlb don't need to be optimized differently. Delete the unloved PageDoubleMap. page_add and page_remove rmap functions must now maintain the subpages_mapcount as well as the subpage _mapcount, when dealing with pte mappings of huge pages; and correct maintenance of NR_ANON_MAPPED and NR_FILE_MAPPED statistics still needs reading through the subpages, using nr_subpages_unmapped() - but only when first or last pmd mapping finds subpages_mapcount raised (double-map case, not the common case). But are those counts (used to decide when to split an anon THP, and in vmscan's pagecache_reclaimable heuristic) correctly maintained? Not quite: since page_remove_rmap() (and also split_huge_pmd()) is often called without page lock, there can be races when a subpage pte mapcount 0<->1 while compound pmd mapcount 0<->1 is scanning - races which the previous implementation had prevented. The statistics might become inaccurate, and even drift down until they underflow through 0. That is not good enough, but is better dealt with in a followup patch. Update a few comments on first and second tail page overlaid fields. hugepage_add_new_anon_rmap() has to "increment" compound_mapcount, but subpages_mapcount and compound_pincount are already correctly at 0, so delete its reinitialization of compound_pincount. A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took 18 seconds on small pages, and used to take 1 second on huge pages, but now takes 119 milliseconds on huge pages. Mapping by pmds a second time used to take 860ms and now takes 92ms; mapping by pmds after mapping by ptes (when the scan is needed) used to take 870ms and now takes 495ms. But there might be some benchmarks which would show a slowdown, because tail struct pages now fall out of cache until final freeing checks them. Link: https://lkml.kernel.org/r/47ad693-717-79c8-e1ba-46c3a6602e48@google.com Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: James Houghton <jthoughton@google.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mina Almasry <almasrymina@google.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev> Cc: Peter Xu <peterx@redhat.com> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Cc: Zach O'Keefe <zokeefe@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Alexander Atanasov
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7c82b3b308 |
mm: Make failslab writable again
In (
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Linus Torvalds
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f2b220ef93 |
A handful of relatively simple documentation fixes, plus a set of patches
catching the Chinese translation up with the front-page rework. -----BEGIN PGP SIGNATURE----- iQFDBAABCAAtFiEEIw+MvkEiF49krdp9F0NaE2wMflgFAmNIPyAPHGNvcmJldEBs d24ubmV0AAoJEBdDWhNsDH5Y6UMH/2ZLziHH0jQkoBAIhxyUzU3ZfXLlq5Xqo6vS oBYfJlYLClY/dmfTc3HAI6UhhJLGTcTNDaC1H4YQdgeP6RVJruFThOYF9WgW0FFl SgsBKhTbi3dpfdzjID8bJM7ytkbIvV4voNh52J9L1TA3z/CPxKSiXCScFAH/o12t E+CMjtmgi2P8w3kqgX59FMavp3W8M8HsT6u/wVoKb+zXjjqXGFYEXTjjKUxufRf6 QWkaQGb0PHq9+2hAhgF4vdy4tWB9lr7r2ENZ8YKUkYUYfv5KGAqt39J7A4rC+g7w 4Rvzznd0BJv3nuZ4rdxom7cOJ77i3lmWSJ65FoDHNeQ/8VBNuZc= =UpLC -----END PGP SIGNATURE----- Merge tag 'docs-6.1-2' of git://git.lwn.net/linux Pull documentation fixes from Jonathan Corbet: "A handful of relatively simple documentation fixes, plus a set of patches catching the Chinese translation up with the front-page rework" * tag 'docs-6.1-2' of git://git.lwn.net/linux: Documentation: rtla: Correct command line example docs/zh_CN: add a man-pages link to zh_CN/index.rst docs/zh_CN: Rewrite the Chinese translation front page docs/zh_CN: add zh_CN/arch.rst docs/zh_CN: promote the title of zh_CN/process/index.rst docs/zh_CN: Update the translation of page_owner to 6.0-rc7 docs/zh_CN: Update the translation of ksm to 6.0-rc7 docs/howto: Replace abundoned URL of gmane.org Documentation: ubifs: Fix compression idiom Documentation/mm/page_owner.rst: delete frequently changing experimental data docs/zh_CN: Fix build warning docs: ftrace: Correct access mode |
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Linus Torvalds
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27bc50fc90 |
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any negative reports (or any positive ones, come to that). - Also the Maple Tree from Liam R. Howlett. An overlapping range-based tree for vmas. It it apparently slight more efficient in its own right, but is mainly targeted at enabling work to reduce mmap_lock contention. Liam has identified a number of other tree users in the kernel which could be beneficially onverted to mapletrees. Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat (https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com). This has yet to be addressed due to Liam's unfortunately timed vacation. He is now back and we'll get this fixed up. - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses clang-generated instrumentation to detect used-unintialized bugs down to the single bit level. KMSAN keeps finding bugs. New ones, as well as the legacy ones. - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of memory into THPs. - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support file/shmem-backed pages. - userfaultfd updates from Axel Rasmussen - zsmalloc cleanups from Alexey Romanov - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure - Huang Ying adds enhancements to NUMA balancing memory tiering mode's page promotion, with a new way of detecting hot pages. - memcg updates from Shakeel Butt: charging optimizations and reduced memory consumption. - memcg cleanups from Kairui Song. - memcg fixes and cleanups from Johannes Weiner. - Vishal Moola provides more folio conversions - Zhang Yi removed ll_rw_block() :( - migration enhancements from Peter Xu - migration error-path bugfixes from Huang Ying - Aneesh Kumar added ability for a device driver to alter the memory tiering promotion paths. For optimizations by PMEM drivers, DRM drivers, etc. - vma merging improvements from Jakub Matěn. - NUMA hinting cleanups from David Hildenbrand. - xu xin added aditional userspace visibility into KSM merging activity. - THP & KSM code consolidation from Qi Zheng. - more folio work from Matthew Wilcox. - KASAN updates from Andrey Konovalov. - DAMON cleanups from Kaixu Xia. - DAMON work from SeongJae Park: fixes, cleanups. - hugetlb sysfs cleanups from Muchun Song. - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core. -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY0HaPgAKCRDdBJ7gKXxA joPjAQDZ5LlRCMWZ1oxLP2NOTp6nm63q9PWcGnmY50FjD/dNlwEAnx7OejCLWGWf bbTuk6U2+TKgJa4X7+pbbejeoqnt5QU= =xfWx -----END PGP SIGNATURE----- Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in linux-next for a couple of months without, to my knowledge, any negative reports (or any positive ones, come to that). - Also the Maple Tree from Liam Howlett. An overlapping range-based tree for vmas. It it apparently slightly more efficient in its own right, but is mainly targeted at enabling work to reduce mmap_lock contention. Liam has identified a number of other tree users in the kernel which could be beneficially onverted to mapletrees. Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat at [1]. This has yet to be addressed due to Liam's unfortunately timed vacation. He is now back and we'll get this fixed up. - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses clang-generated instrumentation to detect used-unintialized bugs down to the single bit level. KMSAN keeps finding bugs. New ones, as well as the legacy ones. - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of memory into THPs. - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support file/shmem-backed pages. - userfaultfd updates from Axel Rasmussen - zsmalloc cleanups from Alexey Romanov - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure - Huang Ying adds enhancements to NUMA balancing memory tiering mode's page promotion, with a new way of detecting hot pages. - memcg updates from Shakeel Butt: charging optimizations and reduced memory consumption. - memcg cleanups from Kairui Song. - memcg fixes and cleanups from Johannes Weiner. - Vishal Moola provides more folio conversions - Zhang Yi removed ll_rw_block() :( - migration enhancements from Peter Xu - migration error-path bugfixes from Huang Ying - Aneesh Kumar added ability for a device driver to alter the memory tiering promotion paths. For optimizations by PMEM drivers, DRM drivers, etc. - vma merging improvements from Jakub Matěn. - NUMA hinting cleanups from David Hildenbrand. - xu xin added aditional userspace visibility into KSM merging activity. - THP & KSM code consolidation from Qi Zheng. - more folio work from Matthew Wilcox. - KASAN updates from Andrey Konovalov. - DAMON cleanups from Kaixu Xia. - DAMON work from SeongJae Park: fixes, cleanups. - hugetlb sysfs cleanups from Muchun Song. - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core. Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1] * tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits) hugetlb: allocate vma lock for all sharable vmas hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer hugetlb: fix vma lock handling during split vma and range unmapping mglru: mm/vmscan.c: fix imprecise comments mm/mglru: don't sync disk for each aging cycle mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol mm: memcontrol: use do_memsw_account() in a few more places mm: memcontrol: deprecate swapaccounting=0 mode mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled mm/secretmem: remove reduntant return value mm/hugetlb: add available_huge_pages() func mm: remove unused inline functions from include/linux/mm_inline.h selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd selftests/vm: add thp collapse shmem testing selftests/vm: add thp collapse file and tmpfs testing selftests/vm: modularize thp collapse memory operations selftests/vm: dedup THP helpers mm/khugepaged: add tracepoint to hpage_collapse_scan_file() mm/madvise: add file and shmem support to MADV_COLLAPSE ... |
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Yixuan Cao
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0719fdba54 |
Documentation/mm/page_owner.rst: delete frequently changing experimental data
The kernel size changes due to many factors, such as compiler version, configuration, and the build environment. This makes size comparison figures irrelevant to reader's setup. Remove these figures and describe the effects of page owner to the kernel size in general instead. Thanks for Jonathan Corbet, Bagas Sanjaya and Mike Rapoport's constructive suggestions. Signed-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn> Link: https://lore.kernel.org/r/20221005145525.10359-1-caoyixuan2019@email.szu.edu.cn Signed-off-by: Jonathan Corbet <corbet@lwn.net> |
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Linus Torvalds
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52abb27abf |
slab fixes for 6.1-rc1
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Merge tag 'slab-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab fixes from Vlastimil Babka:
- The "common kmalloc v4" series [1] by Hyeonggon Yoo.
While the plan after LPC is to try again if it's possible to get rid
of SLOB and SLAB (and if any critical aspect of those is not possible
to achieve with SLUB today, modify it accordingly), it will take a
while even in case there are no objections.
Meanwhile this is a nice cleanup and some parts (e.g. to the
tracepoints) will be useful even if we end up with a single slab
implementation in the future:
- Improves the mm/slab_common.c wrappers to allow deleting
duplicated code between SLAB and SLUB.
- Large kmalloc() allocations in SLAB are passed to page allocator
like in SLUB, reducing number of kmalloc caches.
- Removes the {kmem_cache_alloc,kmalloc}_node variants of
tracepoints, node id parameter added to non-_node variants.
- Addition of kmalloc_size_roundup()
The first two patches from a series by Kees Cook [2] that introduce
kmalloc_size_roundup(). This will allow merging of per-subsystem
patches using the new function and ultimately stop (ab)using ksize()
in a way that causes ongoing trouble for debugging functionality and
static checkers.
- Wasted kmalloc() memory tracking in debugfs alloc_traces
A patch from Feng Tang that enhances the existing debugfs
alloc_traces file for kmalloc caches with information about how much
space is wasted by allocations that needs less space than the
particular kmalloc cache provides.
- My series [3] to fix validation races for caches with enabled
debugging:
- By decoupling the debug cache operation more from non-debug
fastpaths, extra locking simplifications were possible and thus
done afterwards.
- Additional cleanup of PREEMPT_RT specific code on top, by Thomas
Gleixner.
- A late fix for slab page leaks caused by the series, by Feng
Tang.
- Smaller fixes and cleanups:
- Unneeded variable removals, by ye xingchen
- A cleanup removing a BUG_ON() in create_unique_id(), by Chao Yu
Link: https://lore.kernel.org/all/20220817101826.236819-1-42.hyeyoo@gmail.com/ [1]
Link: https://lore.kernel.org/all/20220923202822.2667581-1-keescook@chromium.org/ [2]
Link: https://lore.kernel.org/all/20220823170400.26546-1-vbabka@suse.cz/ [3]
* tag 'slab-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab: (30 commits)
mm/slub: fix a slab missed to be freed problem
slab: Introduce kmalloc_size_roundup()
slab: Remove __malloc attribute from realloc functions
mm/slub: clean up create_unique_id()
mm/slub: enable debugging memory wasting of kmalloc
slub: Make PREEMPT_RT support less convoluted
mm/slub: simplify __cmpxchg_double_slab() and slab_[un]lock()
mm/slub: convert object_map_lock to non-raw spinlock
mm/slub: remove slab_lock() usage for debug operations
mm/slub: restrict sysfs validation to debug caches and make it safe
mm/sl[au]b: check if large object is valid in __ksize()
mm/slab_common: move declaration of __ksize() to mm/slab.h
mm/slab_common: drop kmem_alloc & avoid dereferencing fields when not using
mm/slab_common: unify NUMA and UMA version of tracepoints
mm/sl[au]b: cleanup kmem_cache_alloc[_node]_trace()
mm/sl[au]b: generalize kmalloc subsystem
mm/slub: move free_debug_processing() further
mm/sl[au]b: introduce common alloc/free functions without tracepoint
mm/slab: kmalloc: pass requests larger than order-1 page to page allocator
mm/slab_common: cleanup kmalloc_large()
...
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Qi Zheng
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21fbd59136 |
ksm: add the ksm prefix to the names of the ksm private structures
In order to prevent the name of the private structure of ksm from being the same as the name of the common structure used in subsequent patches, prefix their names with ksm in advance. Link: https://lkml.kernel.org/r/20220831031951.43152-5-zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Vernon Yang
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9a7d7a80e1 |
Documentation/mm: modify page_referenced to folio_referenced
Since commit
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Yu Zhao
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8be976a093 |
mm: multi-gen LRU: design doc
Add a design doc. Link: https://lkml.kernel.org/r/20220918080010.2920238-15-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Brian Geffon <bgeffon@google.com> Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org> Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name> Acked-by: Steven Barrett <steven@liquorix.net> Acked-by: Suleiman Souhlal <suleiman@google.com> Tested-by: Daniel Byrne <djbyrne@mtu.edu> Tested-by: Donald Carr <d@chaos-reins.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru> Tested-by: Shuang Zhai <szhai2@cs.rochester.edu> Tested-by: Sofia Trinh <sofia.trinh@edi.works> Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michael Larabel <Michael@MichaelLarabel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Feng Tang
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6edf2576a6 |
mm/slub: enable debugging memory wasting of kmalloc
kmalloc's API family is critical for mm, with one nature that it will
round up the request size to a fixed one (mostly power of 2). Say
when user requests memory for '2^n + 1' bytes, actually 2^(n+1) bytes
could be allocated, so in worst case, there is around 50% memory
space waste.
The wastage is not a big issue for requests that get allocated/freed
quickly, but may cause problems with objects that have longer life
time.
We've met a kernel boot OOM panic (v5.10), and from the dumped slab
info:
[ 26.062145] kmalloc-2k 814056KB 814056KB
From debug we found there are huge number of 'struct iova_magazine',
whose size is 1032 bytes (1024 + 8), so each allocation will waste
1016 bytes. Though the issue was solved by giving the right (bigger)
size of RAM, it is still nice to optimize the size (either use a
kmalloc friendly size or create a dedicated slab for it).
And from lkml archive, there was another crash kernel OOM case [1]
back in 2019, which seems to be related with the similar slab waste
situation, as the log is similar:
[ 4.332648] iommu: Adding device 0000:20:02.0 to group 16
[ 4.338946] swapper/0 invoked oom-killer: gfp_mask=0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null), order=0, oom_score_adj=0
...
[ 4.857565] kmalloc-2048 59164KB 59164KB
The crash kernel only has 256M memory, and 59M is pretty big here.
(Note: the related code has been changed and optimised in recent
kernel [2], these logs are just picked to demo the problem, also
a patch changing its size to 1024 bytes has been merged)
So add an way to track each kmalloc's memory waste info, and
leverage the existing SLUB debug framework (specifically
SLUB_STORE_USER) to show its call stack of original allocation,
so that user can evaluate the waste situation, identify some hot
spots and optimize accordingly, for a better utilization of memory.
The waste info is integrated into existing interface:
'/sys/kernel/debug/slab/kmalloc-xx/alloc_traces', one example of
'kmalloc-4k' after boot is:
126 ixgbe_alloc_q_vector+0xbe/0x830 [ixgbe] waste=233856/1856 age=280763/281414/282065 pid=1330 cpus=32 nodes=1
__kmem_cache_alloc_node+0x11f/0x4e0
__kmalloc_node+0x4e/0x140
ixgbe_alloc_q_vector+0xbe/0x830 [ixgbe]
ixgbe_init_interrupt_scheme+0x2ae/0xc90 [ixgbe]
ixgbe_probe+0x165f/0x1d20 [ixgbe]
local_pci_probe+0x78/0xc0
work_for_cpu_fn+0x26/0x40
...
which means in 'kmalloc-4k' slab, there are 126 requests of
2240 bytes which got a 4KB space (wasting 1856 bytes each
and 233856 bytes in total), from ixgbe_alloc_q_vector().
And when system starts some real workload like multiple docker
instances, there could are more severe waste.
[1]. https://lkml.org/lkml/2019/8/12/266
[2]. https://lore.kernel.org/lkml/2920df89-9975-5785-f79b-257d3052dfaf@huawei.com/
[Thanks Hyeonggon for pointing out several bugs about sorting/format]
[Thanks Vlastimil for suggesting way to reduce memory usage of
orig_size and keep it only for kmalloc objects]
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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Kassey Li
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8f0efa81df |
mm/page_owner.c: add llseek for page_owner
It is too slow to dump all the pages, in some usage we just want to dump a given start pfn, for example: a CMA range or a single page. To speed up and save time, this change allows specifying of a start pfn by adding llseek for page_owner. Link: https://lkml.kernel.org/r/20220818022425.31056-1-quic_yingangl@quicinc.com Signed-off-by: Kassey Li <quic_yingangl@quicinc.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Fabio M. De Francesco
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a9e9c93966 |
Documentation/mm: add details about kmap_local_page() and preemption
What happens if a thread is preempted after mapping pages with
kmap_local_page() was questioned recently.[1]
Commit
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Fabio M. De Francesco
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84b86f6054 |
Documentation/mm: rrefer kmap_local_page() and avoid kmap()
The reasoning for converting kmap() to kmap_local_page() was questioned recently.[1] There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) kmap() also requires global TLB invalidation when its pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. Warn users to avoid the use of kmap() and instead use kmap_local_page(), by designing their code to map pages in the same context the mapping will be used. [1] https://lore.kernel.org/lkml/1891319.taCxCBeP46@opensuse/ Link: https://lkml.kernel.org/r/20220728154844.10874-6-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Suggested-by: Ira Weiny <ira.weiny@intel.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Peter Collingbourne <pcc@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Fabio M. De Francesco
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6b3afe2eee |
Documentation/mm: avoid invalid use of addresses from kmap_local_page()
Users of kmap_local_page() must be absolutely sure to not hand kernel virtual address obtained calling kmap_local_page() on highmem pages to other contexts because those pointers are thread local, therefore, they are no longer valid across different contexts. Extend the documentation of kmap_local_page() to warn users about the above-mentioned potential invalid use of pointers returned by kmap_local_page(). Link: https://lkml.kernel.org/r/20220728154844.10874-5-fmdefrancesco@gmail.com Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Suggested-by: Ira Weiny <ira.weiny@intel.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Peter Collingbourne <pcc@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Fabio M. De Francesco
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516ea046ec |
Documentation/mm: don't kmap*() pages which can't come from HIGHMEM
There is no need to kmap*() pages which are guaranteed to come from
ZONE_NORMAL (or lower). Linux has currently several call sites of
kmap{,_atomic,_local_page}() on pages which are clearly known which can't
come from ZONE_HIGHMEM.
Therefore, add a paragraph to highmem.rst, to explain better that a plain
page_address() may be used for getting the address of pages which cannot
come from ZONE_HIGHMEM, although it is always safe to use
kmap_local_page() / kunmap_local() also on those pages.
Link: https://lkml.kernel.org/r/20220728154844.10874-4-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Muchun Song
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838691a1c0 |
mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst
All the comments which explains how HVO works are moved to
vmemmap_dedup.rst since
commit
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Muchun Song
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dff033818a |
mm: hugetlb_vmemmap: introduce the name HVO
It it inconvenient to mention the feature of optimizing vmemmap pages associated with HugeTLB pages when communicating with others since there is no specific or abbreviated name for it when it is first introduced. Let us give it a name HVO (HugeTLB Vmemmap Optimization) from now. This commit also updates the document about "hugetlb_free_vmemmap" by the way discussed in thread [1]. Link: https://lore.kernel.org/all/21aae898-d54d-cc4b-a11f-1bb7fddcfffa@redhat.com/ [1] Link: https://lkml.kernel.org/r/20220628092235.91270-4-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Will Deacon <will@kernel.org> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Linus Torvalds
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6614a3c316 |
- The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
Lin, Yang Shi, Anshuman Khandual and Mike Rapoport
- Some kmemleak fixes from Patrick Wang and Waiman Long
- DAMON updates from SeongJae Park
- memcg debug/visibility work from Roman Gushchin
- vmalloc speedup from Uladzislau Rezki
- more folio conversion work from Matthew Wilcox
- enhancements for coherent device memory mapping from Alex Sierra
- addition of shared pages tracking and CoW support for fsdax, from
Shiyang Ruan
- hugetlb optimizations from Mike Kravetz
- Mel Gorman has contributed some pagealloc changes to improve latency
and realtime behaviour.
- mprotect soft-dirty checking has been improved by Peter Xu
- Many other singleton patches all over the place
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Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"Most of the MM queue. A few things are still pending.
Liam's maple tree rework didn't make it. This has resulted in a few
other minor patch series being held over for next time.
Multi-gen LRU still isn't merged as we were waiting for mapletree to
stabilize. The current plan is to merge MGLRU into -mm soon and to
later reintroduce mapletree, with a view to hopefully getting both
into 6.1-rc1.
Summary:
- The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
Lin, Yang Shi, Anshuman Khandual and Mike Rapoport
- Some kmemleak fixes from Patrick Wang and Waiman Long
- DAMON updates from SeongJae Park
- memcg debug/visibility work from Roman Gushchin
- vmalloc speedup from Uladzislau Rezki
- more folio conversion work from Matthew Wilcox
- enhancements for coherent device memory mapping from Alex Sierra
- addition of shared pages tracking and CoW support for fsdax, from
Shiyang Ruan
- hugetlb optimizations from Mike Kravetz
- Mel Gorman has contributed some pagealloc changes to improve
latency and realtime behaviour.
- mprotect soft-dirty checking has been improved by Peter Xu
- Many other singleton patches all over the place"
[ XFS merge from hell as per Darrick Wong in
https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ]
* tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits)
tools/testing/selftests/vm/hmm-tests.c: fix build
mm: Kconfig: fix typo
mm: memory-failure: convert to pr_fmt()
mm: use is_zone_movable_page() helper
hugetlbfs: fix inaccurate comment in hugetlbfs_statfs()
hugetlbfs: cleanup some comments in inode.c
hugetlbfs: remove unneeded header file
hugetlbfs: remove unneeded hugetlbfs_ops forward declaration
hugetlbfs: use helper macro SZ_1{K,M}
mm: cleanup is_highmem()
mm/hmm: add a test for cross device private faults
selftests: add soft-dirty into run_vmtests.sh
selftests: soft-dirty: add test for mprotect
mm/mprotect: fix soft-dirty check in can_change_pte_writable()
mm: memcontrol: fix potential oom_lock recursion deadlock
mm/gup.c: fix formatting in check_and_migrate_movable_page()
xfs: fail dax mount if reflink is enabled on a partition
mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
userfaultfd: don't fail on unrecognized features
hugetlb_cgroup: fix wrong hugetlb cgroup numa stat
...
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Mike Rapoport
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ee65728e10 |
docs: rename Documentation/vm to Documentation/mm
so it will be consistent with code mm directory and with Documentation/admin-guide/mm and won't be confused with virtual machines. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Tested-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Acked-by: Wu XiangCheng <bobwxc@email.cn> |