<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/include/linux/mm_types.h, branch v6.11.2</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>Merge tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2024-07-22T00:15:46+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-07-22T00:15:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fbc90c042cd1dc7258ebfebe6d226017e5b5ac8c'/>
<id>fbc90c042cd1dc7258ebfebe6d226017e5b5ac8c</id>
<content type='text'>
Pull MM updates from Andrew Morton:

 - In the series "mm: Avoid possible overflows in dirty throttling" Jan
   Kara addresses a couple of issues in the writeback throttling code.
   These fixes are also targetted at -stable kernels.

 - Ryusuke Konishi's series "nilfs2: fix potential issues related to
   reserved inodes" does that. This should actually be in the
   mm-nonmm-stable tree, along with the many other nilfs2 patches. My
   bad.

 - More folio conversions from Kefeng Wang in the series "mm: convert to
   folio_alloc_mpol()"

 - Kemeng Shi has sent some cleanups to the writeback code in the series
   "Add helper functions to remove repeated code and improve readability
   of cgroup writeback"

 - Kairui Song has made the swap code a little smaller and a little
   faster in the series "mm/swap: clean up and optimize swap cache
   index".

 - In the series "mm/memory: cleanly support zeropage in
   vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
   Hildenbrand has reworked the rather sketchy handling of the use of
   the zeropage in MAP_SHARED mappings. I don't see any runtime effects
   here - more a cleanup/understandability/maintainablity thing.

 - Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling
   of higher addresses, for aarch64. The (poorly named) series is
   "Restructure va_high_addr_switch".

 - The core TLB handling code gets some cleanups and possible slight
   optimizations in Bang Li's series "Add update_mmu_tlb_range() to
   simplify code".

 - Jane Chu has improved the handling of our
   fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in
   the series "Enhance soft hwpoison handling and injection".

 - Jeff Johnson has sent a billion patches everywhere to add
   MODULE_DESCRIPTION() to everything. Some landed in this pull.

 - In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang
   has simplified migration's use of hardware-offload memory copying.

 - Yosry Ahmed performs more folio API conversions in his series "mm:
   zswap: trivial folio conversions".

 - In the series "large folios swap-in: handle refault cases first",
   Chuanhua Han inches us forward in the handling of large pages in the
   swap code. This is a cleanup and optimization, working toward the end
   objective of full support of large folio swapin/out.

 - In the series "mm,swap: cleanup VMA based swap readahead window
   calculation", Huang Ying has contributed some cleanups and a possible
   fixlet to his VMA based swap readahead code.

 - In the series "add mTHP support for anonymous shmem" Baolin Wang has
   taught anonymous shmem mappings to use multisize THP. By default this
   is a no-op - users must opt in vis sysfs controls. Dramatic
   improvements in pagefault latency are realized.

 - David Hildenbrand has some cleanups to our remaining use of
   page_mapcount() in the series "fs/proc: move page_mapcount() to
   fs/proc/internal.h".

 - David also has some highmem accounting cleanups in the series
   "mm/highmem: don't track highmem pages manually".

 - Build-time fixes and cleanups from John Hubbard in the series
   "cleanups, fixes, and progress towards avoiding "make headers"".

 - Cleanups and consolidation of the core pagemap handling from Barry
   Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
   and utilize them".

 - Lance Yang's series "Reclaim lazyfree THP without splitting" has
   reduced the latency of the reclaim of pmd-mapped THPs under fairly
   common circumstances. A 10x speedup is seen in a microbenchmark.

   It does this by punting to aother CPU but I guess that's a win unless
   all CPUs are pegged.

 - hugetlb_cgroup cleanups from Xiu Jianfeng in the series
   "mm/hugetlb_cgroup: rework on cftypes".

 - Miaohe Lin's series "Some cleanups for memory-failure" does just that
   thing.

 - Someone other than SeongJae has developed a DAMON feature in Honggyu
   Kim's series "DAMON based tiered memory management for CXL memory".
   This adds DAMON features which may be used to help determine the
   efficiency of our placement of CXL/PCIe attached DRAM.

 - DAMON user API centralization and simplificatio work in SeongJae
   Park's series "mm/damon: introduce DAMON parameters online commit
   function".

 - In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
   David Hildenbrand does some maintenance work on zsmalloc - partially
   modernizing its use of pageframe fields.

 - Kefeng Wang provides more folio conversions in the series "mm: remove
   page_maybe_dma_pinned() and page_mkclean()".

 - More cleanup from David Hildenbrand, this time in the series
   "mm/memory_hotplug: use PageOffline() instead of PageReserved() for
   !ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline()
   pages" and permits the removal of some virtio-mem hacks.

 - Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
   __folio_add_anon_rmap()" is a cleanup to the anon folio handling in
   preparation for mTHP (multisize THP) swapin.

 - Kefeng Wang's series "mm: improve clear and copy user folio"
   implements more folio conversions, this time in the area of large
   folio userspace copying.

 - The series "Docs/mm/damon/maintaier-profile: document a mailing tool
   and community meetup series" tells people how to get better involved
   with other DAMON developers. From SeongJae Park.

 - A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
   that.

 - David Hildenbrand sends along more cleanups, this time against the
   migration code. The series is "mm/migrate: move NUMA hinting fault
   folio isolation + checks under PTL".

 - Jan Kara has found quite a lot of strangenesses and minor errors in
   the readahead code. He addresses this in the series "mm: Fix various
   readahead quirks".

 - SeongJae Park's series "selftests/damon: test DAMOS tried regions and
   {min,max}_nr_regions" adds features and addresses errors in DAMON's
   self testing code.

 - Gavin Shan has found a userspace-triggerable WARN in the pagecache
   code. The series "mm/filemap: Limit page cache size to that supported
   by xarray" addresses this. The series is marked cc:stable.

 - Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
   and cleanup" cleans up and slightly optimizes KSM.

 - Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
   code motion. The series (which also makes the memcg-v1 code
   Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put
   under config option" and "mm: memcg: put cgroup v1-specific memcg
   data under CONFIG_MEMCG_V1"

 - Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
   adds an additional feature to this cgroup-v2 control file.

 - The series "Userspace controls soft-offline pages" from Jiaqi Yan
   permits userspace to stop the kernel's automatic treatment of
   excessive correctable memory errors. In order to permit userspace to
   monitor and handle this situation.

 - Kefeng Wang's series "mm: migrate: support poison recover from
   migrate folio" teaches the kernel to appropriately handle migration
   from poisoned source folios rather than simply panicing.

 - SeongJae Park's series "Docs/damon: minor fixups and improvements"
   does those things.

 - In the series "mm/zsmalloc: change back to per-size_class lock"
   Chengming Zhou improves zsmalloc's scalability and memory
   utilization.

 - Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
   pinning memfd folios" makes the GUP code use FOLL_PIN rather than
   bare refcount increments. So these paes can first be moved aside if
   they reside in the movable zone or a CMA block.

 - Andrii Nakryiko has added a binary ioctl()-based API to
   /proc/pid/maps for much faster reading of vma information. The series
   is "query VMAs from /proc/&lt;pid&gt;/maps".

 - In the series "mm: introduce per-order mTHP split counters" Lance
   Yang improves the kernel's presentation of developer information
   related to multisize THP splitting.

 - Michael Ellerman has developed the series "Reimplement huge pages
   without hugepd on powerpc (8xx, e500, book3s/64)". This permits
   userspace to use all available huge page sizes.

 - In the series "revert unconditional slab and page allocator fault
   injection calls" Vlastimil Babka removes a performance-affecting and
   not very useful feature from slab fault injection.

* tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits)
  mm/mglru: fix ineffective protection calculation
  mm/zswap: fix a white space issue
  mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio
  mm/hugetlb: fix possible recursive locking detected warning
  mm/gup: clear the LRU flag of a page before adding to LRU batch
  mm/numa_balancing: teach mpol_to_str about the balancing mode
  mm: memcg1: convert charge move flags to unsigned long long
  alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
  lib: reuse page_ext_data() to obtain codetag_ref
  lib: add missing newline character in the warning message
  mm/mglru: fix overshooting shrinker memory
  mm/mglru: fix div-by-zero in vmpressure_calc_level()
  mm/kmemleak: replace strncpy() with strscpy()
  mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
  mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
  mm: ignore data-race in __swap_writepage
  hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
  mm: shmem: rename mTHP shmem counters
  mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async()
  mm/migrate: putback split folios when numa hint migration fails
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull MM updates from Andrew Morton:

 - In the series "mm: Avoid possible overflows in dirty throttling" Jan
   Kara addresses a couple of issues in the writeback throttling code.
   These fixes are also targetted at -stable kernels.

 - Ryusuke Konishi's series "nilfs2: fix potential issues related to
   reserved inodes" does that. This should actually be in the
   mm-nonmm-stable tree, along with the many other nilfs2 patches. My
   bad.

 - More folio conversions from Kefeng Wang in the series "mm: convert to
   folio_alloc_mpol()"

 - Kemeng Shi has sent some cleanups to the writeback code in the series
   "Add helper functions to remove repeated code and improve readability
   of cgroup writeback"

 - Kairui Song has made the swap code a little smaller and a little
   faster in the series "mm/swap: clean up and optimize swap cache
   index".

 - In the series "mm/memory: cleanly support zeropage in
   vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David
   Hildenbrand has reworked the rather sketchy handling of the use of
   the zeropage in MAP_SHARED mappings. I don't see any runtime effects
   here - more a cleanup/understandability/maintainablity thing.

 - Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling
   of higher addresses, for aarch64. The (poorly named) series is
   "Restructure va_high_addr_switch".

 - The core TLB handling code gets some cleanups and possible slight
   optimizations in Bang Li's series "Add update_mmu_tlb_range() to
   simplify code".

 - Jane Chu has improved the handling of our
   fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in
   the series "Enhance soft hwpoison handling and injection".

 - Jeff Johnson has sent a billion patches everywhere to add
   MODULE_DESCRIPTION() to everything. Some landed in this pull.

 - In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang
   has simplified migration's use of hardware-offload memory copying.

 - Yosry Ahmed performs more folio API conversions in his series "mm:
   zswap: trivial folio conversions".

 - In the series "large folios swap-in: handle refault cases first",
   Chuanhua Han inches us forward in the handling of large pages in the
   swap code. This is a cleanup and optimization, working toward the end
   objective of full support of large folio swapin/out.

 - In the series "mm,swap: cleanup VMA based swap readahead window
   calculation", Huang Ying has contributed some cleanups and a possible
   fixlet to his VMA based swap readahead code.

 - In the series "add mTHP support for anonymous shmem" Baolin Wang has
   taught anonymous shmem mappings to use multisize THP. By default this
   is a no-op - users must opt in vis sysfs controls. Dramatic
   improvements in pagefault latency are realized.

 - David Hildenbrand has some cleanups to our remaining use of
   page_mapcount() in the series "fs/proc: move page_mapcount() to
   fs/proc/internal.h".

 - David also has some highmem accounting cleanups in the series
   "mm/highmem: don't track highmem pages manually".

 - Build-time fixes and cleanups from John Hubbard in the series
   "cleanups, fixes, and progress towards avoiding "make headers"".

 - Cleanups and consolidation of the core pagemap handling from Barry
   Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers
   and utilize them".

 - Lance Yang's series "Reclaim lazyfree THP without splitting" has
   reduced the latency of the reclaim of pmd-mapped THPs under fairly
   common circumstances. A 10x speedup is seen in a microbenchmark.

   It does this by punting to aother CPU but I guess that's a win unless
   all CPUs are pegged.

 - hugetlb_cgroup cleanups from Xiu Jianfeng in the series
   "mm/hugetlb_cgroup: rework on cftypes".

 - Miaohe Lin's series "Some cleanups for memory-failure" does just that
   thing.

 - Someone other than SeongJae has developed a DAMON feature in Honggyu
   Kim's series "DAMON based tiered memory management for CXL memory".
   This adds DAMON features which may be used to help determine the
   efficiency of our placement of CXL/PCIe attached DRAM.

 - DAMON user API centralization and simplificatio work in SeongJae
   Park's series "mm/damon: introduce DAMON parameters online commit
   function".

 - In the series "mm: page_type, zsmalloc and page_mapcount_reset()"
   David Hildenbrand does some maintenance work on zsmalloc - partially
   modernizing its use of pageframe fields.

 - Kefeng Wang provides more folio conversions in the series "mm: remove
   page_maybe_dma_pinned() and page_mkclean()".

 - More cleanup from David Hildenbrand, this time in the series
   "mm/memory_hotplug: use PageOffline() instead of PageReserved() for
   !ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline()
   pages" and permits the removal of some virtio-mem hacks.

 - Barry Song's series "mm: clarify folio_add_new_anon_rmap() and
   __folio_add_anon_rmap()" is a cleanup to the anon folio handling in
   preparation for mTHP (multisize THP) swapin.

 - Kefeng Wang's series "mm: improve clear and copy user folio"
   implements more folio conversions, this time in the area of large
   folio userspace copying.

 - The series "Docs/mm/damon/maintaier-profile: document a mailing tool
   and community meetup series" tells people how to get better involved
   with other DAMON developers. From SeongJae Park.

 - A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does
   that.

 - David Hildenbrand sends along more cleanups, this time against the
   migration code. The series is "mm/migrate: move NUMA hinting fault
   folio isolation + checks under PTL".

 - Jan Kara has found quite a lot of strangenesses and minor errors in
   the readahead code. He addresses this in the series "mm: Fix various
   readahead quirks".

 - SeongJae Park's series "selftests/damon: test DAMOS tried regions and
   {min,max}_nr_regions" adds features and addresses errors in DAMON's
   self testing code.

 - Gavin Shan has found a userspace-triggerable WARN in the pagecache
   code. The series "mm/filemap: Limit page cache size to that supported
   by xarray" addresses this. The series is marked cc:stable.

 - Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations
   and cleanup" cleans up and slightly optimizes KSM.

 - Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of
   code motion. The series (which also makes the memcg-v1 code
   Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put
   under config option" and "mm: memcg: put cgroup v1-specific memcg
   data under CONFIG_MEMCG_V1"

 - Dan Schatzberg's series "Add swappiness argument to memory.reclaim"
   adds an additional feature to this cgroup-v2 control file.

 - The series "Userspace controls soft-offline pages" from Jiaqi Yan
   permits userspace to stop the kernel's automatic treatment of
   excessive correctable memory errors. In order to permit userspace to
   monitor and handle this situation.

 - Kefeng Wang's series "mm: migrate: support poison recover from
   migrate folio" teaches the kernel to appropriately handle migration
   from poisoned source folios rather than simply panicing.

 - SeongJae Park's series "Docs/damon: minor fixups and improvements"
   does those things.

 - In the series "mm/zsmalloc: change back to per-size_class lock"
   Chengming Zhou improves zsmalloc's scalability and memory
   utilization.

 - Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for
   pinning memfd folios" makes the GUP code use FOLL_PIN rather than
   bare refcount increments. So these paes can first be moved aside if
   they reside in the movable zone or a CMA block.

 - Andrii Nakryiko has added a binary ioctl()-based API to
   /proc/pid/maps for much faster reading of vma information. The series
   is "query VMAs from /proc/&lt;pid&gt;/maps".

 - In the series "mm: introduce per-order mTHP split counters" Lance
   Yang improves the kernel's presentation of developer information
   related to multisize THP splitting.

 - Michael Ellerman has developed the series "Reimplement huge pages
   without hugepd on powerpc (8xx, e500, book3s/64)". This permits
   userspace to use all available huge page sizes.

 - In the series "revert unconditional slab and page allocator fault
   injection calls" Vlastimil Babka removes a performance-affecting and
   not very useful feature from slab fault injection.

* tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits)
  mm/mglru: fix ineffective protection calculation
  mm/zswap: fix a white space issue
  mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio
  mm/hugetlb: fix possible recursive locking detected warning
  mm/gup: clear the LRU flag of a page before adding to LRU batch
  mm/numa_balancing: teach mpol_to_str about the balancing mode
  mm: memcg1: convert charge move flags to unsigned long long
  alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting
  lib: reuse page_ext_data() to obtain codetag_ref
  lib: add missing newline character in the warning message
  mm/mglru: fix overshooting shrinker memory
  mm/mglru: fix div-by-zero in vmpressure_calc_level()
  mm/kmemleak: replace strncpy() with strscpy()
  mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC
  mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB
  mm: ignore data-race in __swap_writepage
  hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr
  mm: shmem: rename mTHP shmem counters
  mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async()
  mm/migrate: putback split folios when numa hint migration fails
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/memcg: alignment memcg_data define condition</title>
<updated>2024-07-15T08:42:30+00:00</updated>
<author>
<name>Alex Shi (Tencent)</name>
<email>alexs@kernel.org</email>
</author>
<published>2024-07-12T04:14:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a52c6330ff2fe1163333fa6609bdc6e8763ec286'/>
<id>a52c6330ff2fe1163333fa6609bdc6e8763ec286</id>
<content type='text'>
commit 21c690a349ba ("mm: introduce slabobj_ext to support slab object
extensions") changed the folio/page-&gt;memcg_data define condition from
MEMCG to SLAB_OBJ_EXT. This action make memcg_data exposed while !MEMCG.

As Vlastimil Babka suggested, let's add _unused_slab_obj_exts for
SLAB_MATCH for slab.obj_exts while !MEMCG. That could resolve the match
issue, clean up the feature logical.

Signed-off-by: Alex Shi (Tencent) &lt;alexs@kernel.org&gt;
Cc: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Cc: Yoann Congal &lt;yoann.congal@smile.fr&gt;
Cc: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 21c690a349ba ("mm: introduce slabobj_ext to support slab object
extensions") changed the folio/page-&gt;memcg_data define condition from
MEMCG to SLAB_OBJ_EXT. This action make memcg_data exposed while !MEMCG.

As Vlastimil Babka suggested, let's add _unused_slab_obj_exts for
SLAB_MATCH for slab.obj_exts while !MEMCG. That could resolve the match
issue, clean up the feature logical.

Signed-off-by: Alex Shi (Tencent) &lt;alexs@kernel.org&gt;
Cc: Randy Dunlap &lt;rdunlap@infradead.org&gt;
Cc: Yoann Congal &lt;yoann.congal@smile.fr&gt;
Cc: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Cc: Petr Mladek &lt;pmladek@suse.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: allow reuse of the lower 16 bit of the page type with an actual type</title>
<updated>2024-07-04T02:30:16+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2024-05-29T11:19:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8db00ad5646171880239b7f10e333278f63d8fcf'/>
<id>8db00ad5646171880239b7f10e333278f63d8fcf</id>
<content type='text'>
As long as the owner sets a page type first, we can allow reuse of the
lower 16 bit: sufficient to store an offset into a 64 KiB page, which is
the maximum base page size in *common* configurations (ignoring the 256
KiB variant).  Restrict it to the head page.

We'll use that for zsmalloc next, to set a proper type while still reusing
that field to store information (offset into a base page) that cannot go
elsewhere for now.

Let's reserve the lower 16 bit for that purpose and for catching mapcount
underflows, and let's reduce PAGE_TYPE_BASE to a single bit.

Note that we will still have to overflow the mapcount quite a lot until we
would actually indicate a valid page type.

Start handing out the type bits from highest to lowest, to make it clearer
how many bits for types we have left.  Out of 15 bit we can use for types,
we currently use 6.  If we run out of bits before we have better typing
(e.g., memdesc), we can always investigate storing a value instead [1].

[1] https://lore.kernel.org/all/00ba1dff-7c05-46e8-b0d9-a78ac1cfc198@redhat.com/

[akpm@linux-foundation.org: fix PG_hugetlb typo, per David]
Link: https://lkml.kernel.org/r/20240529111904.2069608-3-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Tested-by: Sergey Senozhatsky &lt;senozhatsky@chromium.org&gt;	[zram/zsmalloc workloads]
Cc: Hyeonggon Yoo &lt;42.hyeyoo@gmail.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Mike Rapoport (IBM) &lt;rppt@kernel.org&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As long as the owner sets a page type first, we can allow reuse of the
lower 16 bit: sufficient to store an offset into a 64 KiB page, which is
the maximum base page size in *common* configurations (ignoring the 256
KiB variant).  Restrict it to the head page.

We'll use that for zsmalloc next, to set a proper type while still reusing
that field to store information (offset into a base page) that cannot go
elsewhere for now.

Let's reserve the lower 16 bit for that purpose and for catching mapcount
underflows, and let's reduce PAGE_TYPE_BASE to a single bit.

Note that we will still have to overflow the mapcount quite a lot until we
would actually indicate a valid page type.

Start handing out the type bits from highest to lowest, to make it clearer
how many bits for types we have left.  Out of 15 bit we can use for types,
we currently use 6.  If we run out of bits before we have better typing
(e.g., memdesc), we can always investigate storing a value instead [1].

[1] https://lore.kernel.org/all/00ba1dff-7c05-46e8-b0d9-a78ac1cfc198@redhat.com/

[akpm@linux-foundation.org: fix PG_hugetlb typo, per David]
Link: https://lkml.kernel.org/r/20240529111904.2069608-3-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Tested-by: Sergey Senozhatsky &lt;senozhatsky@chromium.org&gt;	[zram/zsmalloc workloads]
Cc: Hyeonggon Yoo &lt;42.hyeyoo@gmail.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Mike Rapoport (IBM) &lt;rppt@kernel.org&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: update _mapcount and page_type documentation</title>
<updated>2024-07-04T02:30:16+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2024-05-29T11:18:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6d21dde7adc0a2deb9e0c6b06f42be3f88ca180d'/>
<id>6d21dde7adc0a2deb9e0c6b06f42be3f88ca180d</id>
<content type='text'>
Patch series "mm: page_type, zsmalloc and page_mapcount_reset()", v2.

Wanting to remove the remaining abuser of _mapcount/page_type along with
page_mapcount_reset(), I stumbled over zsmalloc, which is yet to be
converted away from "struct page" [1].

Unfortunately, we cannot stop using the page_type field in zsmalloc code
completely for its own purposes.  All other fields in "struct page" are
used one way or the other.  Could we simply store a 2-byte offset value at
the beginning of each page?  Likely, but that will require a bit more
work; and once we have memdesc we might want to move the offset in there
(struct zsalloc?) again.

...  but we can limit the abuse to 16 bit, glue it to a page type that
must be set, and document it.  page_has_type() will always successfully
indicate such zsmalloc pages, and such zsmalloc pages only.

We lose zsmalloc support for PAGE_SIZE &gt; 64KB, which should be tolerable. 
We could use more bits from the page type, but 16 bit sounds like a good
idea for now.

So clarify the _mapcount/page_type documentation, use a proper page_type
for zsmalloc, and remove page_mapcount_reset().

[1] https://lore.kernel.org/all/20231130101242.2590384-1-42.hyeyoo@gmail.com/


This patch (of 6):

Let's make it clearer that _mapcount must no longer be used for own
purposes, and how _mapcount and page_type behaves nowadays (also in the
context of hugetlb folios, which are typed folios that will be mapped to
user space).

Move the documentation regarding "-1" over from page_mapcount_reset(),
which we will remove next.  Move "page_type" before "mapcount", to make it
clearer what typed folios are.

Link: https://lkml.kernel.org/r/20240529111904.2069608-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240529111904.2069608-2-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Tested-by: Sergey Senozhatsky &lt;senozhatsky@chromium.org&gt;	[zram/zsmalloc workloads]
Cc: Hyeonggon Yoo &lt;42.hyeyoo@gmail.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Mike Rapoport (IBM) &lt;rppt@kernel.org&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mm: page_type, zsmalloc and page_mapcount_reset()", v2.

Wanting to remove the remaining abuser of _mapcount/page_type along with
page_mapcount_reset(), I stumbled over zsmalloc, which is yet to be
converted away from "struct page" [1].

Unfortunately, we cannot stop using the page_type field in zsmalloc code
completely for its own purposes.  All other fields in "struct page" are
used one way or the other.  Could we simply store a 2-byte offset value at
the beginning of each page?  Likely, but that will require a bit more
work; and once we have memdesc we might want to move the offset in there
(struct zsalloc?) again.

...  but we can limit the abuse to 16 bit, glue it to a page type that
must be set, and document it.  page_has_type() will always successfully
indicate such zsmalloc pages, and such zsmalloc pages only.

We lose zsmalloc support for PAGE_SIZE &gt; 64KB, which should be tolerable. 
We could use more bits from the page type, but 16 bit sounds like a good
idea for now.

So clarify the _mapcount/page_type documentation, use a proper page_type
for zsmalloc, and remove page_mapcount_reset().

[1] https://lore.kernel.org/all/20231130101242.2590384-1-42.hyeyoo@gmail.com/


This patch (of 6):

Let's make it clearer that _mapcount must no longer be used for own
purposes, and how _mapcount and page_type behaves nowadays (also in the
context of hugetlb folios, which are typed folios that will be mapped to
user space).

Move the documentation regarding "-1" over from page_mapcount_reset(),
which we will remove next.  Move "page_type" before "mapcount", to make it
clearer what typed folios are.

Link: https://lkml.kernel.org/r/20240529111904.2069608-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240529111904.2069608-2-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Tested-by: Sergey Senozhatsky &lt;senozhatsky@chromium.org&gt;	[zram/zsmalloc workloads]
Cc: Hyeonggon Yoo &lt;42.hyeyoo@gmail.com&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Mike Rapoport (IBM) &lt;rppt@kernel.org&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/ksm: fix ksm_zero_pages accounting</title>
<updated>2024-06-06T02:19:26+00:00</updated>
<author>
<name>Chengming Zhou</name>
<email>chengming.zhou@linux.dev</email>
</author>
<published>2024-05-28T05:15:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6'/>
<id>c2dc78b86e0821ecf9a9d0c35dba2618279a5bb6</id>
<content type='text'>
We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.

So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.

Fix it by changing to use atomic_long_t, and the same case with the
mm-&gt;ksm_zero_pages.

Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e01d ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f0704 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou &lt;chengming.zhou@linux.dev&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Ran Xiaokai &lt;ran.xiaokai@zte.com.cn&gt;
Cc: Stefan Roesch &lt;shr@devkernel.io&gt;
Cc: xu xin &lt;xu.xin16@zte.com.cn&gt;
Cc: Yang Yang &lt;yang.yang29@zte.com.cn&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We normally ksm_zero_pages++ in ksmd when page is merged with zero page,
but ksm_zero_pages-- is done from page tables side, where there is no any
accessing protection of ksm_zero_pages.

So we can read very exceptional value of ksm_zero_pages in rare cases,
such as -1, which is very confusing to users.

Fix it by changing to use atomic_long_t, and the same case with the
mm-&gt;ksm_zero_pages.

Link: https://lkml.kernel.org/r/20240528-b4-ksm-counters-v3-2-34bb358fdc13@linux.dev
Fixes: e2942062e01d ("ksm: count all zero pages placed by KSM")
Fixes: 6080d19f0704 ("ksm: add ksm zero pages for each process")
Signed-off-by: Chengming Zhou &lt;chengming.zhou@linux.dev&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: Ran Xiaokai &lt;ran.xiaokai@zte.com.cn&gt;
Cc: Stefan Roesch &lt;shr@devkernel.io&gt;
Cc: xu xin &lt;xu.xin16@zte.com.cn&gt;
Cc: Yang Yang &lt;yang.yang29@zte.com.cn&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/madvise: introduce clear_young_dirty_ptes() batch helper</title>
<updated>2024-05-06T00:53:42+00:00</updated>
<author>
<name>Lance Yang</name>
<email>ioworker0@gmail.com</email>
</author>
<published>2024-04-18T13:44:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1b68112c40395b3b0fed3c8bb648e2d9d0b37ec2'/>
<id>1b68112c40395b3b0fed3c8bb648e2d9d0b37ec2</id>
<content type='text'>
Patch series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free",
v10.

This patchset adds support for lazyfreeing multi-size THP (mTHP) without
needing to first split the large folio via split_folio().  However, we
still need to split a large folio that is not fully mapped within the
target range.

If a large folio is locked or shared, or if we fail to split it, we just
leave it in place and advance to the next PTE in the range.  But note that
the behavior is changed; previously, any failure of this sort would cause
the entire operation to give up.  As large folios become more common,
sticking to the old way could result in wasted opportunities.

Performance Testing
===================

On an Intel I5 CPU, lazyfreeing a 1GiB VMA backed by PTE-mapped folios of
the same size results in the following runtimes for madvise(MADV_FREE) in
seconds (shorter is better):

Folio Size |   Old    |   New    | Change
------------------------------------------
      4KiB | 0.590251 | 0.590259 |    0%
     16KiB | 2.990447 | 0.185655 |  -94%
     32KiB | 2.547831 | 0.104870 |  -95%
     64KiB | 2.457796 | 0.052812 |  -97%
    128KiB | 2.281034 | 0.032777 |  -99%
    256KiB | 2.230387 | 0.017496 |  -99%
    512KiB | 2.189106 | 0.010781 |  -99%
   1024KiB | 2.183949 | 0.007753 |  -99%
   2048KiB | 0.002799 | 0.002804 |    0%


This patch (of 4):

This commit introduces clear_young_dirty_ptes() to replace mkold_ptes(). 
By doing so, we can use the same function for both use cases
(madvise_pageout and madvise_free), and it also provides the flexibility
to only clear the dirty flag in the future if needed.

Link: https://lkml.kernel.org/r/20240418134435.6092-1-ioworker0@gmail.com
Link: https://lkml.kernel.org/r/20240418134435.6092-2-ioworker0@gmail.com
Signed-off-by: Lance Yang &lt;ioworker0@gmail.com&gt;
Suggested-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Barry Song &lt;21cnbao@gmail.com&gt;
Cc: Jeff Xie &lt;xiehuan09@gmail.com&gt;
Cc: Kefeng Wang &lt;wangkefeng.wang@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Cc: Muchun Song &lt;songmuchun@bytedance.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: Yin Fengwei &lt;fengwei.yin@intel.com&gt;
Cc: Zach O'Keefe &lt;zokeefe@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free",
v10.

This patchset adds support for lazyfreeing multi-size THP (mTHP) without
needing to first split the large folio via split_folio().  However, we
still need to split a large folio that is not fully mapped within the
target range.

If a large folio is locked or shared, or if we fail to split it, we just
leave it in place and advance to the next PTE in the range.  But note that
the behavior is changed; previously, any failure of this sort would cause
the entire operation to give up.  As large folios become more common,
sticking to the old way could result in wasted opportunities.

Performance Testing
===================

On an Intel I5 CPU, lazyfreeing a 1GiB VMA backed by PTE-mapped folios of
the same size results in the following runtimes for madvise(MADV_FREE) in
seconds (shorter is better):

Folio Size |   Old    |   New    | Change
------------------------------------------
      4KiB | 0.590251 | 0.590259 |    0%
     16KiB | 2.990447 | 0.185655 |  -94%
     32KiB | 2.547831 | 0.104870 |  -95%
     64KiB | 2.457796 | 0.052812 |  -97%
    128KiB | 2.281034 | 0.032777 |  -99%
    256KiB | 2.230387 | 0.017496 |  -99%
    512KiB | 2.189106 | 0.010781 |  -99%
   1024KiB | 2.183949 | 0.007753 |  -99%
   2048KiB | 0.002799 | 0.002804 |    0%


This patch (of 4):

This commit introduces clear_young_dirty_ptes() to replace mkold_ptes(). 
By doing so, we can use the same function for both use cases
(madvise_pageout and madvise_free), and it also provides the flexibility
to only clear the dirty flag in the future if needed.

Link: https://lkml.kernel.org/r/20240418134435.6092-1-ioworker0@gmail.com
Link: https://lkml.kernel.org/r/20240418134435.6092-2-ioworker0@gmail.com
Signed-off-by: Lance Yang &lt;ioworker0@gmail.com&gt;
Suggested-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Barry Song &lt;21cnbao@gmail.com&gt;
Cc: Jeff Xie &lt;xiehuan09@gmail.com&gt;
Cc: Kefeng Wang &lt;wangkefeng.wang@huawei.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Minchan Kim &lt;minchan@kernel.org&gt;
Cc: Muchun Song &lt;songmuchun@bytedance.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: Yin Fengwei &lt;fengwei.yin@intel.com&gt;
Cc: Zach O'Keefe &lt;zokeefe@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: track mapcount of large folios in single value</title>
<updated>2024-05-06T00:53:28+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2024-04-09T19:22:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=05c5323b2a344c19c51cd1b91a4ab9ae90853794'/>
<id>05c5323b2a344c19c51cd1b91a4ab9ae90853794</id>
<content type='text'>
Let's track the mapcount of large folios in a single value.  The mapcount
of a large folio currently corresponds to the sum of the entire mapcount
and all page mapcounts.

This sum is what we actually want to know in folio_mapcount() and it is
also sufficient for implementing folio_mapped().

With PTE-mapped THP becoming more important and more widely used, we want
to avoid looping over all pages of a folio just to obtain the mapcount of
large folios.  The comment "In the common case, avoid the loop when no
pages mapped by PTE" in folio_total_mapcount() does no longer hold for
mTHP that are always mapped by PTE.

Further, we are planning on using folio_mapcount() more frequently, and
might even want to remove page mapcounts for large folios in some kernel
configs.  Therefore, allow for reading the mapcount of large folios
efficiently and atomically without looping over any pages.

Maintain the mapcount also for hugetlb pages for simplicity.  Use the new
mapcount to implement folio_mapcount() and folio_mapped().  Make
page_mapped() simply call folio_mapped().  We can now get rid of
folio_large_is_mapped().

_nr_pages_mapped is now only used in rmap code and for debugging purposes.
Keep folio_nr_pages_mapped() around, but document that its use should be
limited to rmap internals and debugging purposes.

This change implies one additional atomic add/sub whenever
mapping/unmapping (parts of) a large folio.

As we now batch RMAP operations for PTE-mapped THP during fork(), during
unmap/zap, and when PTE-remapping a PMD-mapped THP, and we adjust the
large mapcount for a PTE batch only once, the added overhead in the common
case is small.  Only when unmapping individual pages of a large folio
(e.g., during COW), the overhead might be bigger in comparison, but it's
essentially one additional atomic operation.

Note that before the new mapcount would overflow, already our refcount
would overflow: each mapping requires a folio reference.  Extend the
focumentation of folio_mapcount().

Link: https://lkml.kernel.org/r/20240409192301.907377-5-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Yin Fengwei &lt;fengwei.yin@intel.com&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: John Paul Adrian Glaubitz &lt;glaubitz@physik.fu-berlin.de&gt;
Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Richard Chang &lt;richardycc@google.com&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Let's track the mapcount of large folios in a single value.  The mapcount
of a large folio currently corresponds to the sum of the entire mapcount
and all page mapcounts.

This sum is what we actually want to know in folio_mapcount() and it is
also sufficient for implementing folio_mapped().

With PTE-mapped THP becoming more important and more widely used, we want
to avoid looping over all pages of a folio just to obtain the mapcount of
large folios.  The comment "In the common case, avoid the loop when no
pages mapped by PTE" in folio_total_mapcount() does no longer hold for
mTHP that are always mapped by PTE.

Further, we are planning on using folio_mapcount() more frequently, and
might even want to remove page mapcounts for large folios in some kernel
configs.  Therefore, allow for reading the mapcount of large folios
efficiently and atomically without looping over any pages.

Maintain the mapcount also for hugetlb pages for simplicity.  Use the new
mapcount to implement folio_mapcount() and folio_mapped().  Make
page_mapped() simply call folio_mapped().  We can now get rid of
folio_large_is_mapped().

_nr_pages_mapped is now only used in rmap code and for debugging purposes.
Keep folio_nr_pages_mapped() around, but document that its use should be
limited to rmap internals and debugging purposes.

This change implies one additional atomic add/sub whenever
mapping/unmapping (parts of) a large folio.

As we now batch RMAP operations for PTE-mapped THP during fork(), during
unmap/zap, and when PTE-remapping a PMD-mapped THP, and we adjust the
large mapcount for a PTE batch only once, the added overhead in the common
case is small.  Only when unmapping individual pages of a large folio
(e.g., during COW), the overhead might be bigger in comparison, but it's
essentially one additional atomic operation.

Note that before the new mapcount would overflow, already our refcount
would overflow: each mapping requires a folio reference.  Extend the
focumentation of folio_mapcount().

Link: https://lkml.kernel.org/r/20240409192301.907377-5-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Yin Fengwei &lt;fengwei.yin@intel.com&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: Hugh Dickins &lt;hughd@google.com&gt;
Cc: John Paul Adrian Glaubitz &lt;glaubitz@physik.fu-berlin.de&gt;
Cc: Jonathan Corbet &lt;corbet@lwn.net&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Miaohe Lin &lt;linmiaohe@huawei.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Naoya Horiguchi &lt;nao.horiguchi@gmail.com&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Cc: Richard Chang &lt;richardycc@google.com&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Yang Shi &lt;shy828301@gmail.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: switch mm-&gt;get_unmapped_area() to a flag</title>
<updated>2024-04-26T03:56:25+00:00</updated>
<author>
<name>Rick Edgecombe</name>
<email>rick.p.edgecombe@intel.com</email>
</author>
<published>2024-03-26T02:16:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=529ce23a764f25d172198b4c6ba90f1e2ad17f93'/>
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<content type='text'>
The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.

Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required.  In addition future changes will want to add versions of the
functions that take additional arguments.  So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.

Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags().  Most MM flags get clobbered on fork.  In the
pre-existing behavior mm-&gt;get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.

Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag.  Then drop the mm-&gt;get_unmapped_area() function pointer.  Leave the
get_unmapped_area() pointer in struct file_operations alone.  The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm-&gt;get_unmapped_area() from indirect
branches into a direct ones.

The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel.  On x86, the change yielded a ~1%
improvement there on a retpoline config.

In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct. 
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.

Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe &lt;rick.p.edgecombe@intel.com&gt;
Acked-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Acked-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Reviewed-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Aneesh Kumar K.V &lt;aneesh.kumar@kernel.org&gt;
Cc: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Deepak Gupta &lt;debug@rivosinc.com&gt;
Cc: Guo Ren &lt;guoren@kernel.org&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: H. Peter Anvin (Intel) &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Naveen N. Rao &lt;naveen.n.rao@linux.ibm.com&gt;
Cc: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
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<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The mm_struct contains a function pointer *get_unmapped_area(), which is
set to either arch_get_unmapped_area() or arch_get_unmapped_area_topdown()
during the initialization of the mm.

Since the function pointer only ever points to two functions that are
named the same across all arch's, a function pointer is not really
required.  In addition future changes will want to add versions of the
functions that take additional arguments.  So to save a pointers worth of
bytes in mm_struct, and prevent adding additional function pointers to
mm_struct in future changes, remove it and keep the information about
which get_unmapped_area() to use in a flag.

Add the new flag to MMF_INIT_MASK so it doesn't get clobbered on fork by
mmf_init_flags().  Most MM flags get clobbered on fork.  In the
pre-existing behavior mm-&gt;get_unmapped_area() would get copied to the new
mm in dup_mm(), so not clobbering the flag preserves the existing behavior
around inheriting the topdown-ness.

Introduce a helper, mm_get_unmapped_area(), to easily convert code that
refers to the old function pointer to instead select and call either
arch_get_unmapped_area() or arch_get_unmapped_area_topdown() based on the
flag.  Then drop the mm-&gt;get_unmapped_area() function pointer.  Leave the
get_unmapped_area() pointer in struct file_operations alone.  The main
purpose of this change is to reorganize in preparation for future changes,
but it also converts the calls of mm-&gt;get_unmapped_area() from indirect
branches into a direct ones.

The stress-ng bigheap benchmark calls realloc a lot, which calls through
get_unmapped_area() in the kernel.  On x86, the change yielded a ~1%
improvement there on a retpoline config.

In testing a few x86 configs, removing the pointer unfortunately didn't
result in any actual size reductions in the compiled layout of mm_struct. 
But depending on compiler or arch alignment requirements, the change could
shrink the size of mm_struct.

Link: https://lkml.kernel.org/r/20240326021656.202649-3-rick.p.edgecombe@intel.com
Signed-off-by: Rick Edgecombe &lt;rick.p.edgecombe@intel.com&gt;
Acked-by: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Acked-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Reviewed-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Acked-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Aneesh Kumar K.V &lt;aneesh.kumar@kernel.org&gt;
Cc: Borislav Petkov (AMD) &lt;bp@alien8.de&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Deepak Gupta &lt;debug@rivosinc.com&gt;
Cc: Guo Ren &lt;guoren@kernel.org&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: H. Peter Anvin (Intel) &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "James E.J. Bottomley" &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Naveen N. Rao &lt;naveen.n.rao@linux.ibm.com&gt;
Cc: Nicholas Piggin &lt;npiggin@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: optimize CONFIG_PER_VMA_LOCK member placement in vm_area_struct</title>
<updated>2024-04-26T03:56:24+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2024-03-27T14:35:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3b612c8f069fecb84af277c8b90e14832749ceca'/>
<id>3b612c8f069fecb84af277c8b90e14832749ceca</id>
<content type='text'>
Currently, we end up wasting some memory in each vm_area_struct. Pahole
states that:
	[...]
	int                        vm_lock_seq;          /*    40     4 */

	/* XXX 4 bytes hole, try to pack */

	struct vma_lock *          vm_lock;              /*    48     8 */
	bool                       detached;             /*    56     1 */

	/* XXX 7 bytes hole, try to pack */
	[...]

Let's reduce the holes and memory wastage by moving the bool:
	[...]
	bool                       detached;             /*    40     1 */

	/* XXX 3 bytes hole, try to pack */

	int                        vm_lock_seq;          /*    44     4 */
	struct vma_lock *          vm_lock;              /*    48     8 */
	[...]

Effectively shrinking the vm_area_struct with CONFIG_PER_VMA_LOCK by
8 byte.

Likely, we could place "detached" in the lowest bit of vm_lock, but at
least on 64bit that won't really make a difference, so keep it simple.

Link: https://lkml.kernel.org/r/20240327143548.744070-1-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently, we end up wasting some memory in each vm_area_struct. Pahole
states that:
	[...]
	int                        vm_lock_seq;          /*    40     4 */

	/* XXX 4 bytes hole, try to pack */

	struct vma_lock *          vm_lock;              /*    48     8 */
	bool                       detached;             /*    56     1 */

	/* XXX 7 bytes hole, try to pack */
	[...]

Let's reduce the holes and memory wastage by moving the bool:
	[...]
	bool                       detached;             /*    40     1 */

	/* XXX 3 bytes hole, try to pack */

	int                        vm_lock_seq;          /*    44     4 */
	struct vma_lock *          vm_lock;              /*    48     8 */
	[...]

Effectively shrinking the vm_area_struct with CONFIG_PER_VMA_LOCK by
8 byte.

Likely, we could place "detached" in the lowest bit of vm_lock, but at
least on 64bit that won't really make a difference, so keep it simple.

Link: https://lkml.kernel.org/r/20240327143548.744070-1-david@redhat.com
Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: change inlined allocation helpers to account at the call site</title>
<updated>2024-04-26T03:55:59+00:00</updated>
<author>
<name>Suren Baghdasaryan</name>
<email>surenb@google.com</email>
</author>
<published>2024-04-15T02:07:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2c321f3f70bc284510598f712b702ce8d60c4d14'/>
<id>2c321f3f70bc284510598f712b702ce8d60c4d14</id>
<content type='text'>
Main goal of memory allocation profiling patchset is to provide accounting
that is cheap enough to run in production.  To achieve that we inject
counters using codetags at the allocation call sites to account every time
allocation is made.  This injection allows us to perform accounting
efficiently because injected counters are immediately available as opposed
to the alternative methods, such as using _RET_IP_, which would require
counter lookup and appropriate locking that makes accounting much more
expensive.  This method requires all allocation functions to inject
separate counters at their call sites so that their callers can be
individually accounted.  Counter injection is implemented by allocation
hooks which should wrap all allocation functions.

Inlined functions which perform allocations but do not use allocation
hooks are directly charged for the allocations they perform.  In most
cases these functions are just specialized allocation wrappers used from
multiple places to allocate objects of a specific type.  It would be more
useful to do the accounting at their call sites instead.  Instrument these
helpers to do accounting at the call site.  Simple inlined allocation
wrappers are converted directly into macros.  More complex allocators or
allocators with documentation are converted into _noprof versions and
allocation hooks are added.  This allows memory allocation profiling
mechanism to charge allocations to the callers of these functions.

Link: https://lkml.kernel.org/r/20240415020731.1152108-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Acked-by: Jan Kara &lt;jack@suse.cz&gt;		[jbd2]
Cc: Anna Schumaker &lt;anna@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Dennis Zhou &lt;dennis@kernel.org&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: Jakub Sitnicki &lt;jakub@cloudflare.com&gt;
Cc: Jiri Kosina &lt;jikos@kernel.org&gt;
Cc: Joerg Roedel &lt;joro@8bytes.org&gt;
Cc: Joonsoo Kim &lt;iamjoonsoo.kim@lge.com&gt;
Cc: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Paolo Abeni &lt;pabeni@redhat.com&gt;
Cc: Pekka Enberg &lt;penberg@kernel.org&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Theodore Ts'o &lt;tytso@mit.edu&gt;
Cc: Trond Myklebust &lt;trond.myklebust@hammerspace.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Main goal of memory allocation profiling patchset is to provide accounting
that is cheap enough to run in production.  To achieve that we inject
counters using codetags at the allocation call sites to account every time
allocation is made.  This injection allows us to perform accounting
efficiently because injected counters are immediately available as opposed
to the alternative methods, such as using _RET_IP_, which would require
counter lookup and appropriate locking that makes accounting much more
expensive.  This method requires all allocation functions to inject
separate counters at their call sites so that their callers can be
individually accounted.  Counter injection is implemented by allocation
hooks which should wrap all allocation functions.

Inlined functions which perform allocations but do not use allocation
hooks are directly charged for the allocations they perform.  In most
cases these functions are just specialized allocation wrappers used from
multiple places to allocate objects of a specific type.  It would be more
useful to do the accounting at their call sites instead.  Instrument these
helpers to do accounting at the call site.  Simple inlined allocation
wrappers are converted directly into macros.  More complex allocators or
allocators with documentation are converted into _noprof versions and
allocation hooks are added.  This allows memory allocation profiling
mechanism to charge allocations to the callers of these functions.

Link: https://lkml.kernel.org/r/20240415020731.1152108-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan &lt;surenb@google.com&gt;
Acked-by: Jan Kara &lt;jack@suse.cz&gt;		[jbd2]
Cc: Anna Schumaker &lt;anna@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Dennis Zhou &lt;dennis@kernel.org&gt;
Cc: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Herbert Xu &lt;herbert@gondor.apana.org.au&gt;
Cc: Jakub Kicinski &lt;kuba@kernel.org&gt;
Cc: Jakub Sitnicki &lt;jakub@cloudflare.com&gt;
Cc: Jiri Kosina &lt;jikos@kernel.org&gt;
Cc: Joerg Roedel &lt;joro@8bytes.org&gt;
Cc: Joonsoo Kim &lt;iamjoonsoo.kim@lge.com&gt;
Cc: Kent Overstreet &lt;kent.overstreet@linux.dev&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Cc: Paolo Abeni &lt;pabeni@redhat.com&gt;
Cc: Pekka Enberg &lt;penberg@kernel.org&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Theodore Ts'o &lt;tytso@mit.edu&gt;
Cc: Trond Myklebust &lt;trond.myklebust@hammerspace.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
