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https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git
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https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git
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https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git
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fix try_to_compact_pages() kerneldoc
Link: https://lore.kernel.org/DK7NM9RPUJOD.11PNJJ5N2OBED@linux.dev
Signed-off-by: "Brendan Jackman" <brendan.jackman@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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As we deployed defrag_mode into Meta production, pressure spikes and
excessive swapping were observed on some workloads. Tracing confirmed
that this is unmovable/reclaimable requests spinning in the allocator and
direct reclaim, causing excessive amounts of swap.
The initial plan for defrag_mode was to rely on kswapd/kcompactd to
produce blocks, and if those are overwhelmed under high pressure, let the
allocator fall back (__rmqueue_steal()) after its retry loops. However,
that retrying results in more reclaim on some of these workloads than we'd
hoped, sometimes excessively so, spurred on by the !costly order
conditions in should_reclaim_retry().
The storms are dependent on the request type. Reclaim will inevitably
make room in existing movable blocks, since that's where the LRU pages
live. So if movable requests retry on reclaim, they make progress.
When non-movable requests spin in reclaim that isn't productive. They
cannot use the individually freed pages, and the process is unlikely to
accidentally free whole blocks to meet the ALLOC_NOFRAGMENT bar. They
spin and overreclaim excessively, which tanks performance and triggers
userspace guards like swap exhaustion or pressure based OOM.
To fix this, send non-movable requests, regardless of order, into
pageblock reclaim/compaction. This way, they help move things along to
meet the ALLOC_NOFRAGMENT bar. After this patch, the reclaim storms and
excess OOM rates are no longer observed in production.
The longer-term plan is still to have all requests, including the movable
ones, help make blocks to spread the cost of defragmenting more evenly and
fairly; combined with proper watermarking to reduce allocation latencies
in the common case. However, doing this naively unearths scaling and
concurrency limitations in compaction that need to be addressed first.
Promoting just non-movables for now is the minimally viable bug fix for
the above issue.
Link: https://lore.kernel.org/20260722150006.3848560-5-hannes@cmpxchg.org
Fixes: e3aa7df331bc ("mm: page_alloc: defrag_mode")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The compaction capturing code assumes the allocation request order and
compaction target order are the same. That won't be true once defrag_mode
promotes sub-block allocations to pageblock-order compaction: compaction
targets the larger order, while capture should remain at the original
allocation order.
Move the capture_control to the page allocator and give it its own copies
of what the page freeing path matches against - zone, migratetype and the
allocation order - rather than reaching into compaction's live
compact_control. __alloc_pages_direct_compact() fills in migratetype and
order, and installs and hides current->capture_control around the whole
compaction call; try_to_compact_pages() aims capc->zone at each zone while
it is being compacted. compact_zone_order() no longer deals with capture
at all.
Pass the capture_control through try_to_compact_pages() /
compact_zone_order() in place of the bare struct page **.
No functional change.
Link: https://lore.kernel.org/20260722150006.3848560-4-hannes@cmpxchg.org
Fixes: e3aa7df331bc ("mm: page_alloc: defrag_mode")
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Co-developed-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Gregory Price <gourry@gourry.net>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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While trying to fix a reclaim storm in defrag_mode, I noticed that
non-movable direct compaction is extremely inefficient.
When searching for space to evacuate, compaction only allows blocks of the
same type as the incoming request. This is to prevent migratetype
pollution, where a small non-movable request frees space in a movable
block and provokes the allocator to fall back and pollute it.
This protection is reasonable on one hand, but the downside is that it
makes non-movable direct compaction nearly useless: if we get the type
annotations right, by definition there aren't any movable pages inside the
non-movable blocks it is allowed to scan.
With defrag_mode, the goal is the production of whole blocks, which are
essentially type neutral: __rmqueue_claim() will convert them wholesale on
alloc. This makes type mixing and pollution a non-issue.
Fix the pollution gates to take the requested order into account, and
allow whole-block requests to scan blocks of other types.
The only exception is CMA blocks. That type is sticky and these blocks
cannot be claimed to other types. Continue to be strict with them, and
allow only explicit ALLOC_CMA requests and kcompactd to evacuate them.
Link: https://lore.kernel.org/20260722150006.3848560-3-hannes@cmpxchg.org
Fixes: e3aa7df331bc ("mm: page_alloc: defrag_mode")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Gregory Price <gourry@gourry.net>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm: fix reclaim storms in defrag_mode", v2.
As we deployed vm.defrag_mode=1 in Meta production, some workloads
regressed with recurring pressure spikes and swap storms (which in turn
triggered userspace OOM rules on pressure and swap utilization levels).
Tracing pinned this to non-movable requests spinning and reclaiming
unproductively when kswapd/kcompactd are overwhelmed. Direct reclaim
predominantly frees up pages in movable blocks, but those requests cannot
use that space under defrag_mode rules; and it is unlikely to free up
whole blocks incidentally for __rmqueue_claim() to work.
This series fixes it by making non-movable requests participate in
pageblock production in the allocator slowpath - meaning, they will invoke
direct reclaim and direct compaction with pageblock_order.
That requires some small-ish adjustments up front in the allocator and the
compaction code: three prep patches and the fix last.
The series has been in production against one of the affected workloads
for several weeks and restores the OOM kill rate to !defrag_mode baseline.
This patch (of 4):
A subsequent patch will have some order-0 allocations participate in
compaction under defrag_mode, to stave off extfrag events.
Since this is a sprawling expansion of entry points, and compaction can
enter filesystem paths, add lockdep annotations that catches __GFP_FS
passing errors.
Direct reclaim has had this annotation for a while, and since reclaim and
compaction are usually used in conjunction, this is unlikely to unearth
old bugs. It's more about future proofing and peace of mind.
Link: https://lore.kernel.org/20260722150006.3848560-1-hannes@cmpxchg.org
Link: https://lore.kernel.org/20260722150006.3848560-2-hannes@cmpxchg.org
Fixes: e3aa7df331bc ("mm: page_alloc: defrag_mode")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Gregory Price <gourry@gourry.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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unlock_or_release_subpool() drops spool->lock before calling
subpool_is_free(). However, subpool_is_free() reads fields that are
updated under spool->lock, including count, used_hpages and rsv_hpages.
Keep the free-state evaluation under the same lock that protects those
fields. The reservation accounting and kfree() calls still happen after
dropping spool->lock.
Link: https://lore.kernel.org/20260721035207.1437935-1-chenyichong@uniontech.com
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Three function definitions terminate with '};' instead of '}', which is
unnecessary and inconsistent with kernel coding style:
- damon_pa_initcall() in paddr.c
- damon_va_initcall() in vaddr.c
- damos_get_some_mem_psi_total() in core.c
No functional change intended.
Link: https://lore.kernel.org/20260721135333.241106-1-sj@kernel.org
Signed-off-by: Xuewen Wang <wangxuewen@kylinos.cn>
Reviewed-by: SJ Park <sj@kernel.org>
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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DAMOS_MIGRATE_{HOT,COLD} passes a target NUMA node to migrate_pages().
But alloc_migration_target() only treats mtc->nid as a preferred node
unless __GFP_THISNODE is set. Hence target allocation can fall back to
another node, and migrate_pages() can report success without placing the
folio on the requested target node.
Consider a two-node tiered system where node 0 is a fast tier and node 1
is a CPU-less slow tier such as CXL memory, and the user wants to promote
hot regions from node 1 to node 0 with a command like:
sudo damo start --ops vaddr --target_pid ${workload_pid} \
--damos_action migrate_hot 0 \
--damos_access_rate 70% max
Without the __GFP_THISNODE flag, when the memory allocator finds that node
0 is nearly full, it can fall back to node 1 without waking up kswapd.
Then the pages allocated for migrate_pages() are still on node 1, and the
regions that are expected to be promoted to node 0 are only moved to
different physical pages on node 1.
Meanwhile, both the mm_migrate_pages tracepoint and DAMOS's own sz_applied
statistics (reported via the damos_stat_after_apply_interval tracepoint)
show the migrations as successful, which makes the failure practically
invisible and hard to investigate.
Running a demotion-purpose DAMOS scheme alongside the promotion scheme
does not fully avoid this either. If demotion cannot keep up with the
promotion rate, allocation can still fall back to node 1 during promotion,
and the same misleading statistics show up.
Make DAMON's migration target allocation strict by setting __GFP_THISNODE,
so that a failed allocation on the target node is reported as a failure
instead of silently landing on a different node. This is consistent with
alloc_misplaced_dst_folio(), alloc_demote_folio(), and with
do_move_pages_to_node(), which all use __GFP_THISNODE for migrations to an
explicit destination node.
Link: https://lore.kernel.org/20260721135607.251869-1-sj@kernel.org
Signed-off-by: Jiahui Zhang <jiahuitry@outlook.com>
Reviewed-by: SJ Park <sj@kernel.org>
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/early_ioremap: clarify and clean up
early_ioremap_reset()".
__late_set_fixmap() and __late_clear_fixmap() are only used after
early_ioremap_reset() has been called, but the comment above them does not
say anything about that. So arm64, riscv and powerpc, whose
__set_fixmap() works before and after paging_init(), describe the same
situation in three different ways:
calls reset defines the macros
arm64 yes yes
riscv no yes
powerpc no no
Patch 1 documents when early_ioremap_reset() needs to be called and that
only architectures calling it need to define the macros.
Patches 2 and 3 remove the unneeded riscv macros, which are unreachable,
and the arm64 reset call and macros, which change nothing.
No functional change.
This patch (of 3):
__late_set_fixmap() and __late_clear_fixmap() are only used after
early_ioremap_reset() has been called.
arm64, riscv and powerpc all have a __set_fixmap() that works before and
after paging_init(), so they do not need to call early_ioremap_reset() or
define the macros, but they describe the same situation in three different
ways:
calls reset defines the macros
arm64 yes yes
riscv no yes
powerpc no no
The existing comment is vague and allows all three. Replace it with
comments that make it clear when the reset and the macros are needed.
No functional change.
Link: https://lore.kernel.org/20260708170647.362562-1-ekffu200098@gmail.com
Link: https://lore.kernel.org/20260708170647.362562-2-ekffu200098@gmail.com
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Commit a67fe41e214f ("mm: rmap: support batched unmapping for file large
folios") extended batched unmapping for file folios. That also required
making pte_install_uffd_wp_if_needed() support batching, but that was left
out for the time being. Correctness was maintained by stopping batching
if the VMA the folio belongs to is marked uffd-wp.
Now that cond_install_uffd_wp_ptes() supports batching, call it with the
full batch length and allow folio_unmap_pte_batch() to batch file folios
belonging to uffd-wp VMAs.
For file folios, if the uffd-wp bit is set, unmapping converts present
PTEs into uffd-wp markers. We must ensure that the same PTE range is not
reprocessed by the try_to_unmap_one() loop.
The page_vma_mapped_walk API ensures this: check_pte() only returns true
if any PFN in [pvmw->pfn, pvmw->pfn + nr_pages) is mapped by the PTE.
There is no PFN underlying a uffd-wp marker PTE, so check_pte() returns
false and the walk skips ahead until it reaches a present entry again.
Link: https://lore.kernel.org/20260720065508.2695106-4-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Enable batch setting of uffd-wp PTE markers.
The code paths passing nr > 1 to zap_install_uffd_wp_if_needed() produce
that nr through either folio_pte_batch() or swap_pte_batch(), therefore
batching is correct:
1) All PTEs belong to the same type of VMA: anonymous or non-anonymous,
wp-armed or non-wp-armed.
2) All PTEs are either marked with uffd-wp or not marked with uffd-wp;
the same applies to the pte_swp_uffd_any() check.
3) uffd_supports_wp_marker() is independent of the function parameters.
Use set_pte_at() in a loop instead of set_ptes(), because set_ptes()
cannot handle nonpresent to nonpresent conversion for nr_pages > 1.
Rename the helper to cond_install_uffd_wp_ptes().
Link: https://lore.kernel.org/20260720065508.2695106-3-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Batch unmap of uffd-wp file folios", v2.
Currently, batched unmapping is supported if:
1) folio is a file folio, not belonging to uffd-wp VMA
2) folio is anonymous and not swapbacked (lazyfree), not belonging to
uffd-wp VMA
So the cases which are not supported are
1) folio belonging to uffd-wp VMA
2) folio is anonymous and swapbacked
It is easy to see that this adds a lot of cognitive load while reading
try_to_unmap_one - we need to remember throughout whether nr_pages == 1 or
> 1.
The uffd-wp handling in try_to_unmap_one is regarding preserving the
uffd-wp state for file folios via pte_install_uffd_wp_if_needed (for anon
folio, we handle that while constructing the swap pte).
Stop special casing on uffd-wp VMAs by simply adding batching support to
pte_install_uffd_wp_if_needed.
This patch (of 3):
pte_install_uffd_wp_if_needed() has grown too large for mm_inline.h. Move
it to memory.c.
This helper is only used inside mm/, so declare it in mm/internal.h
instead of a public header.
While at it, convert the comment to kerneldoc and rename the local
arguments from pte/pteval to ptep/pte so the pointer and PTE value are
easier to distinguish.
Link: https://lore.kernel.org/20260720065508.2695106-1-dev.jain@arm.com
Link: https://lore.kernel.org/20260720065508.2695106-2-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Both callers of hugepage_put_subpool() check whether the subpool pointer
is NULL before calling it. Move the NULL check into
hugepage_put_subpool() so callers can use the helper unconditionally.
This is a follow-up cleanup after using hugepage_put_subpool() from the
hugetlbfs_fill_super() failure path.
Link: https://lore.kernel.org/20260720073841.1389354-1-chenyichong@uniontech.com
Signed-off-by: Yichong Chen <chenyichong@uniontech.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Classical LRU protects mapped executable file folios through commit
8cab4754d24a0 ("vmscan: make mapped executable pages the first class
citizen") and commit c909e99364c8 ("vmscan: activate executable pages
after first usage"), giving executable code a better chance to stay in
memory, avoiding IO thrashing and improving workload performance.
However, MGLRU's protection of mapped executable file folios is less
reliable. Although shrink_folio_list() checks references, the access flag
of mapped executable file folios may have already been checked and cleared
by lru_gen_look_around() or walk_mm(). Additionally, folio_update_gen()
or lru_gen_set_refs() only sets the 'PG_referenced' flag for mapped
executable file folios, which causes shrink_folio_list() to ignore the
first usage of these mapped executable file folios and reclaim them
easily.
Follow the classical LRU's logic, promoting mapped executable file folios
after their first usage in folio_update_gen() and lru_gen_set_refs(),
giving executable code a better chance to stay in memory.
On my 32-core Arm machine, with the memcg limit set to 2G, running 'make
-j32' to build kernel showed some improvement in sys time.
base patched
9248.543s 7861.579s
Link: https://lore.kernel.org/f57d94b1d85bb3d620d89bb739128f0d929bf9c6.1784509721.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Add a helper to identify file-backed executable folios to avoid duplicate
code.
No functional changes.
Link: https://lore.kernel.org/2ee74f9f98ac45a2f0db0ceb018e086bdb671d17.1784509721.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "promote mapped executable folios after first usage for
MGLRU", v4.
Now MGLRU's protection of mapped executable file folios is less reliable.
Follow the classical LRU's logic, promoting mapped executable file folios
after their first usage to give executable code a better chance to stay in
memory and improve workload performance (See patch 2 for more details).
This patch (of 3):
Replace use of the legacy vm_flags_t flags with vma_flags_t values for
folio_referenced() and related logic. This is also a preparation for the
following changes.
No functional changes.
Link: https://lore.kernel.org/cover.1784509721.git.baolin.wang@linux.alibaba.com
Link: https://lore.kernel.org/2bd39e16ec19e3e3c4716aa9a1a25775c26cac57.1784509721.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Harry Yoo <harry@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
kmemleak_scan() can run for ages on large debug kernels. It was
causing some soft-lockups which I got fixed with commit
3175fcfec8b16baeb ("mm/kmemleak: avoid soft lockup when scanning task
stacks") with our beloved cond_resched().
I've got the fix above deployed in the Meta fleet, and now I am seeing:
INFO: rcu_tasks detected stalls on tasks:
task:kmemleak state:R ... nvcsw: 274/274 holdout: 1 idle_cpu: -1/3
scan_block
scan_gray_list
kmemleak_scan
and, worse, blocks the callers waiting on that grace period. Here a BPF
struct_ops map free, which waits via synchronize_rcu_mult(call_rcu,
call_rcu_tasks), is stuck long enough to also trip the hung task check:
INFO: task kworker/...:bpf_map_free_deferred blocked for 122 seconds
__wait_rcu_gp
bpf_struct_ops_map_free
Then I've learned that cond_resched() is not an RCU-tasks quiescent
state, so, we need to use stronger primitives.
Use cond_resched_tasks_rcu_qs() at the scan reschedule points so the scan
reports an RCU-tasks quiescent state as it proceeds.
Inspired by commit b96285e10aad ("tracing: Have osnoise_main() add a
quiescent state for task rcu").
Link: https://lore.kernel.org/20260720-kmemleak_rcu_task-v1-1-5b460ade777d@debian.org
Fixes: c4b28963fd79 ("mm/kmemleak: rely on rcu for task stack scanning")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: Breno Leitao <leitao@debian.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Puranjay Mohan <puranjay@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
When mapping /dev/zero with MAP_PRIVATE, one ends up with strange VMAs
originating from Linux's distant past.
These have vma->vm_file set but NULL vma->vm_ops, meaning they satisfy
vma_is_anonymous() but otherwise resemble a file-backed VMA.
The introduction of virtual page offsets and their subsequent use as
indexes for MAP_PRIVATE-file-backed mappings mean the rmap does the right
thing with these but we are left with inconsistencies.
The vma_start_pgoff(vma) == vma_start_virt_pgoff(vma) invariant is true
for all other anonymous VMAs, but not these.
These VMAs are also observable as files in /proc/<pid>/[s]maps but
otherwise behave like anonymous mappings.
Therefore let's make these VMAs actually anonymous at mapping time which
will activate the anonymous code path for mappings.
This means we no longer have to account for this discrepancy anywhere and
no longer have to think about these at all.
A previous commit gave us map_is_dev_zero() to positively identify these
mappings, so we expressly only do so for these alone.
The impact of this change should be low as likely very few are relying
upon this in any case, and in using them are asking for anonymous memory,
so no longer seeing these as file mappings in smaps should have no
meaningful impact.
Update assert_sane_pgoff(), the comment for vma_start_pgoff() and
linear_virt_page_index() to reflect the change.
We make this change in call_mmap_prepare() alone as /dev/zero has been
converted to an mmap_prepare hook and we do not permit nested MAP_PRIVATE
mapping of /dev/zero.
We also remove the now defunct vma_desc_set_anonymous() and eliminate the
temporary bisection hazard fix from the previous commit.
Also update the VMA userland tests to reflect the change.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-13-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In order to use mmap_prepare() with MAP_PRIVATE mappings of /dev/zero
without the success_hook hack we explicitly permitted mmap_prepare
handlers to set NULL vm_ops.
However this is dangerous and we really only want to allow this for
MAP_PRIVATE-mapped /dev/zero.
Make it possible to explicitly identify /dev/zero by setting a global
DEVZERO_MINOR device minor number then explicitly check for this in mmap
code for a MAP_PRIVATE mapping and only set the VMA anonymous if we have
positively identified it.
Then remove all ability for mmap_prepare or mmap hooks to set a VMA
anonymous and update mmap_zero_prepare() to leave it to the core mmap code
to mark the VMA anonymous.
Note that this disallows nested MAP_PRIVATE-mappings of /dev/zero regions.
Doing this would be broken in any case.
We therefore do not need to update the mmap_prepare() compatibility layer
to reflect these changes, as the mmap hook check suffices to disallow this
behaviour.
Now we're setting vma->vm_ops to NULL for an mmap_prepare-initialised
MAP_PRIVATE-/dev/zero mapping, we have to avoid a subtle issue when
updating user-defined fields via set_vma_user_defined_fields().
The default for vma->vm_ops for all mmap_prepare-initialised mappings is
vma_dummy_vm_ops, so map->vm_ops will be set to this and setting
vma->vm_ops to this will render the VMA mistakenly non-anon.
In general, we should never be setting user-defined fields for an
anonymous VMA, so explicitly check for this to avoid doing so for the one
case where a mapping can be both mmap_prepare and anonymous.
Also, in order to avoid a single commit bisection hazard, add a temporary
workaround to set the VMA anonymous only after vma->vm_file is assigned in
__mmap_new_file_vma().
This is because vma_set_range() calls vma_set_pgoff() and
assert_sane_pgoff() in turn, prior to the vma->vm_file being assigned. If
we set the VMA anonymous early then this assert will fail.
This is removed in the subsequent commit.
Also update the VMA userland tests to reflect the change.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-12-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently, anonymous folios belonging to CoW'd MAP_PRIVATE file-backed
mappings are indexed by their page offset within the file in which they
were originally mapped.
This differs from anonymous folios belonging to pure anon mappings which
are indexed by their virtual page offset (the address at which they'd
belong in the VMA when first faulted).
This change fixes this inconsistency, always indexing anonymous folios by
their virtual page offset regardless of the VMA to which they belong.
We have laid the foundations for making this change to the point where we
need only 'switch it on', and this patch switches it on by:
* Using linear_virt_page_index() in __folio_set_anon() to assign the
folio's index to the anonymous linear index rather than the file-backed
one.
* Otherwise using linear_virt_page_index() in all instances where
anonymous folios are being referenced or manipulated.
* Replacing vma_address() with vma_filebacked_address() or
vma_anon_address() as appropriate.
* Updating the rmap lock logic in copy_vma() to also account for virtual
page offsets.
* Updating the merging logic to check that virtual page offsets are
aligned as well as filebacked ones for anonymous or MAP_PRIVATE
file-backed VMAs.
* Updating linear_folio_page_index() to invoke linear_virt_page_index()
if the folio is anonymous.
* Correcting folio_within_range() to use virtual page offset for anonymous
folios.
This will have no impact on merging of anonymous VMAs or shared
file-backed VMAs, whose page offset and anonymous page offset will be
identical.
However, MAP_PRIVATE file-backed mappings must now be aligned on virtual
page offset as well.
In most instances this should have no impact on merging of file-backed
mappings, which are usually not merged all that often, let alone
MAP_PRIVATE mapped ones, and rarely remapped and faulted before being
moved back in place (the case in which a merge may now fail).
One subtle impact of this change is in NUMA interleaving - since commit
88c91dc58582 ("mempolicy: migration attempt to match interleave nodes"),
migration heuristically tries to maintain interleaving behaviour matching
the policy using folio indices.
When doing migration of CoW'd MAP_PRIVATE-file backed ranges, the 'base'
upon which the interleaving behaviour is performed will vary for these
ranges. However the commit notes that ranges spanning multiple VMAs will
already cause varying bases, and that this is an acceptable approximation.
It is very unlikely real world use-cases will be impacted by this
(MAP_PRIVATE file-backed mappings are already an edge case), and all that
will happen is that such ranges will cause interleaving to be rotated over
the CoW'd range, with little to no impact.
This commit lays the foundations for future scalable CoW work which needs
to track some remaps, meaning that most remap tracking can be avoided, and
in nearly all cases the anonymous page offset will be able to be used to
quickly find the VMA in an mm.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-9-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This function is, for now, a placeholder; it will be used in future to
determine whether to use the virtual page index or not, based on whether
the folio is anonymous or not.
Currently it simply wraps linear_page_index(), so this does not change
behaviour.
We update callers that will, once the change is introduced to track
anonymous folios by virtual page offset if MAP_PRIVATE file-backed, need
to determine which index to use based on folio type.
No functional change intended.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-8-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Update the page_vma_mapped_walk structure to track whether the walk is
over an anonymous folio or not.
This is necessary in order to determine the correct VMA page offset
(virtual or not) in vma_address_end() ready for a subsequent change which
adjusts which page offset to use depending on this parameter, and update
the comment slightly.
No functional change intended.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-7-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We must correctly update VMA virtual page offset state on all VMA
operations that would result in it changing, with special attention given
to remapping.
We cover most cases by simply updating vma_set_range() to do so (with a
new virtual page offset parameter), but also notably must update the
merging and mapping logic to propagate this parameter correctly.
The remap logic remains the same - we may update the virtual page offset
if the VMA is unfaulted, but now this applies to MAP_PRIVATE file-backed
mappings too, so we update the code to reflect this.
Note that we use __linear_virt_page_index() upon remap as the VMA may be
shared, in order that we update the field consistently regardless of VMA
type.
Also while we're here, replace a VM_BUG_ON_VMA() with a
VM_WARN_ON_ONCE_VMA().
We also introduce vma_anon_pgoff_addr(), vma_start_anon_pgoff(), and
vma_end_anon_pgoff() which differ from their virtual page offset
equivalents in that a shared file-backed mapping returns its file page
offset otherwise the virtual page offset is used.
This means we don't predicate merges for shared file-backed mappings on
virtual page offset.
We simply ensure state is correctly propagated here, so no functional
changes are intended.
Finally, we update insert_vm_struct() to correctly set the virtual page
offset on insertion of a VMA.
Also update VMA userland tests to reflect this change.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-6-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In cases where we know that the VMA is file-backed, use
vma_filebacked_address() rather than vma_address().
This lays the foundation for using the virtual page offset for anonymous
VMAs via vma_anon_address().
Also add an assert to ensure that the VMA whose address is required is not
anonymous.
No functional change intended.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-5-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This is potentially useful debugging information and matches the existing
page offset provided.
Use the raw __linear_virt_page_index() function so as to always output
this value regardless of whether the mapping is file-backed or not.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-4-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Introduce __vma_address() which abstracts the VMA start page offset field
as pgoff_start, then update vma_address() to use it.
Then introduce vma_anon_address() which does the equivalent of
vma_address(), only using the virtual page offset of the VMA rather than
the file-backed one.
Also add an assert to ensure that the function is not called for mappings
which are file-backed but not MAP_PRIVATE to ensure it is only used in the
correct places.
This will be necessary for determining the address of a folio's index
within a VMA when the folio belongs to a MAP_PRIVATE file-backed VMA but
has been CoW'd, and thus is anonymous, once the anonymous VMA page offset
field is used for the reverse mapping.
No callers are updated, so no functional change intended.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-3-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/rmap: index MAP_PRIVATE file-backed folios by virt
pgoff", v2.
In memory management we've managed to manufacture a great deal of
confusion around the concept of anonymous memory. We have:
1. 'Pure anon' memory - anonymous VMAs whose folios are anonymous and
swap-backed (thus for reclaim purposes, treated as anonymous). These are
simple enough.
2. shmem - file-backed VMAs, file-backed folios (from rmap perspective) so
present in the page cache and mapped by an address_space object, but
whose folios are also swap-backed (thus treated as anonymous for reclaim
purposes).
3. MAP_PRIVATE-mapped /dev/zero - a strange beast whose VMAs have
vma->vm_file set, but whose mmap_prepare callback clears vma->vm_ops to
satisfy vma_is_anonymous(), which results in VMAs that were mmap()'d
referencing a file, but are in every other sense anonymous, including the
folios.
4. Other MAP_PRIVATE-file backed mappings - These possess file-backed VMAs
and have file-backed folios until CoW'd, at which point those CoW'd
folios are anonymous.
This series fixes issues 3 and 4.
In order for us to traverse VMAs using the reverse mapping, we require two
fields - folio->mapping and folio->index. The first tells the rmap code
where to look for VMAs, and the second tells it at which offset the folio
starts within the referenced object.
For anonymous folios, folio->mapping points at an anon_vma object. For
file-backed folios, it points at an address_space. And:
* For file-backed folios folio->index is simply the page offset of the start
of the folio within the file.
* For anonymous folios belonging to pure anon mappings, folio->index is
equal to the virtual page offset of the folio.
* For anonymous folios belonging to file-backed mappings (i.e. CoW'd folios
of a MAP_PRIVATE file-backed mapping), folio->index is equal to the file
page offset.
This series establishes a new virtual page offset property of VMAs to
allow us to map anonymous folios at their virtual page offset, consistent
with pure anon.
The purpose of doing so is to lay the foundations for the scalable CoW
work. This is necessary because scalable CoW looks in the maple tree for
the VMA located at folio->index << PAGE_SHIFT, before falling back to
looking up tracked remaps if necessary.
The MAP_PRIVATE file-backed case means that folio indices will very often
conflict with one another and this remap tracking becomes substantially
more contended, and of course the fast path can never be used.
This also makes it possible, in future, to unshare anonymously mapped
folios with deep fork hierarchies on remap, eliminating the need for remap
tracking in the vast majority of cases.
Similar to page offset of pure anonymous VMAs, we update the virtual page
offset of unfaulted file-backed VMAs on remap, but do not once CoW'd (i.e.
vma->anon_vma is non-NULL).
Overall, there is little impact on mergeability - for shared file-backed
mappings, we treat the anonymous page offset as equal to the file-backed
one (via vma_start_anon_pgoff()), so merge behaviour remains the same
there.
The only impact is on MAP_PRIVATE-mapped file-backed mappings, which must
now match on virtual page offset as well as file page offset to be merged.
To fail to merge like this would require CoW'ing the mapping, then finding
another VMA with identical file and compatible page offset to remap next
to. This is therefore very much an edge case that should have very little
impact (and which scalable CoW may very well address in any case).
We also address the outlier case of MAP_PRIVATE-/dev/zero mappings which
have file page offset but satisfy vma_is_anonymous() by making them truly
anonymous.
This is low-risk as for anything meaningful these mappings behave
anonymously, but it is very beneficial to do so as we eliminate an odd
corner case, and those are notorious for attracting subtle bugs.
This patch (of 15):
This patch establishes fields within the vm_area_struct type to store the
virtual page offset of VMAs.
The virtual page offset of a VMA is equal to vma->vm_start >> PAGE_SHIFT
if they are unfaulted or were not remapped, otherwise it is equal to this
value at the point of first fault.
Currently, anonymous folios belonging to CoW'd MAP_PRIVATE-mapped
file-backed VMAs are tracked by their file offset. By adding virtual
offset as a property of VMAs, we can now track them by their virtual page
offset instead.
By tracking this, we provide the means by which to eliminate this
inconsistency, and more importantly lay the foundations for future work
for the scalable CoW anonymous rmap rework.
This patch simply adds the fields and some simple helpers. Subsequent
patches will update mm code to make use of these fields correctly.
The fields chosen are packed in the VMA such that, for 64-bit kernel
builds, no additional space is taken up.
The first field is present on cacheline 0 containing key VMA fields, and
the second on cacheline 3, which contains file-backed reverse mapping
fields.
Given the relative time spent accessing reverse mapping fields as well as
updating them, there shouldn't be any performance impact here from false
sharing.
Update the VMA userland tests to account for this change.
No callsites are updated yet, so no functional change intended.
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org
Link: https://lore.kernel.org/20260720-b4-scalable-cow-virt-pgoff-v2-1-2d549757a76f@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Xu Xin <xu.xin16@zte.com.cn>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damon_apply_min_nr_regions() repeatedly split each region until its size
becomes small enough to meet the user-defined low limit of the number of
regions. The loop assumes the split operation (damon_split_region_at())
will always succeed and create the new region. But the operation could
silently fail for memory allocation failures, for example.
If such failure happens and the region was the last region, the linked
list-based next region fetching returns invalid pointer. As a result,
invalid memory dereference and corruption could happen. Even if the
corner case is handled, it imposes stress to the allocator by trying split
regions for other targets. Fix the issue by breaking all the loops for
any region split failure.
This means there could be a min_nr_regions violation. It will only rarely
happen since the allocation is arguably too small to fail. Even if it
happens, it is only temporal. damon_apply_min_nr_regions() will be called
again after the aggregation interval.
The user impact of the issue should be minor, since the allocation is
arguably too small to fail. But, it could still theoretically happen, and
the consequence is very bad.
This issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260719155442.88794-1-sj@kernel.org
Link: https://lore.kernel.org/20260717011834.120715-1-sj@kernel.org [1]
Fixes: b1029f29eb1d ("mm/damon/core: split regions for min_nr_regions")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 7.1.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Since commit 42f994b71404 ("mm/damon/core: implement scheme-specific apply
interval"), DAMOS scheme can be applied at any time. At that time,
nr_accesses may not be fully aggregated. But the quota prioritization
score is calculated using the not fully aggregated count. As a result,
the performance of DAMOS could be degraded. Fix by using
damon_nr_accesses_mvsum() instead.
The user impact of the issue is suboptimum DAMOS performance under certain
setups. Nonetheless, the bug was there from the beginning of the setup
availability. In other words, the suboptimum performance is the baseline
of the setup and hence it didn't cause regression. Also the extent of the
suboptimality was not big enough to be found from users and testers.
Still, this is a clear bug that is better to be fixed, and can be easily
fixed.
Link: https://lore.kernel.org/20260719161136.90191-1-sj@kernel.org
Fixes: 42f994b71404 ("mm/damon/core: implement scheme-specific apply interval")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.7.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damon_migrate_folio_list()
In damon_migrate_folio_list(), we're redeclaring folio inside the first
while loop, but it just shadows the outer one. Since the second loop uses
the outer folio anyway, the inner declaration is pointless.
Remove it to consistently reuse the same variable throughout the
function and improve readability.
Link: https://lore.kernel.org/20260718002125.637104-1-lienze@kylinos.cn
Signed-off-by: Enze Li <lienze@kylinos.cn>
Reviewed-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damon_test_commit_target_regions_for() traverses expected values array
after damon_commit_target_regions() call. It assumes
damon_commit_target_regions() made expected number of regions. It might
not. Because the traversal is made based on the region count, it could do
out of bounds access to the expectation value array.
The consequent user impact (out-of-bound access) is quite bad. The
realistic user impact would be limited, though. It would affect only test
run setups.
Fix it by testing if the number of regions was also changed as expected
and exit early for the failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-8-sj@kernel.org
Link: https://lore.kernel.org/20260713144757.39740-1-sj@kernel.org [1]
Fixes: 603f67eb91e0 ("mm/damon/tests/core-kunit: add damon_commit_target_regions() test")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 6.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damos_test_commit_quota_goals_for() traverses damos quota goals after
damos_commit_quota_goals() call. It assumes damos_commit_quota_goals()
made expected numbers of goals. It might not. Because the traversal is
made based on destination struct length, it could do out of bounds access
for source expectation value array.
The consequent user impact (out-of-bound access ) is quite bad. The
realistic user impact would be limited though. It would affect only test
run setups.
Fix it by testing if the number of goals was also changed as expected and
exit early for the failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-7-sj@kernel.org
Link: https://lore.kernel.org/20260713144757.39740-1-sj@kernel.org [1]
Fixes: d9adfb8a28e7 ("mm/damon/tests/core-kunit: add damos_commit_quota_goals() test")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 6.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damos_test_commit_dests_for() traverse damos action destinations after
damos_commit_dests(). It assumes damos_commit_dests() made expected
numbers of destinations for source and destination structures. It might
not. Because the traversal is made based on destination struct length, it
could do out of bounds access for source value expectation.
The consequent user impact (out-of-bound access ) is quite bad. The
realistic user impact would be limited, though. It would affect only test
run setups.
Fix it by exiting early for the number of regions test failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-6-sj@kernel.org
Link: https://lore.kernel.org/20260713144757.39740-1-sj@kernel.org [1]
Fixes: eec573b8dd65 ("mm/damon/tests/core-kunit: add damos_commit_dests() test")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 6.19.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damos_test_filter_out() test checks if damos_filter_match() of an address
filter splits the region as expected under a given condition. But, the
test continued regardless of the split successes. As a result, the later
part of the test could dereference invalid pointers that returned from
damon_next_region(). Further, it could corrupt memory from
damon_destroy_region().
The consequent user impact (memory corruption) is quite bad. The
realistic user impact would be limited, though. It would affect only test
run setups.
Fix it by exiting early for the number of regions test failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-5-sj@kernel.org
Link: https://lore.kernel.org/20260714142352.100478-1-sj@kernel.org [1]
Fixes: 26713c890875 ("mm/damon/core-test: add a unit test for __damos_filter_out()")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 6.6.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
damon_do_test_apply_three_regions() iterates regions after
damon_set_regions() call assuming the function would succeed at setting
the number of regions the same to the expected one. It might have failed.
In this case, __nth_region_of() in the iteration could return NULL and
NULL dereference can happen in the test.
The consequent user impact (NULL dereference) is quite bad. The realistic
user impact would be limited, though. It would affect only test run
setups.
Fix it by testing if the number of regions was also changed as expected
and exit early for the failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-4-sj@kernel.org
Link: https://lore.kernel.org/20260713144757.39740-1-sj@kernel.org [1]
Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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damon_test_split_at() test next region that is assumed to be created by
damon_split_region_at() invocation. But the split might fail. In this
case, the succeeding test may dereference invalid pointers returned by
damon_next_region().
The invalid pointer may not cause a really bad user impact, because of the
implementation detail. It would only read wrong contents in the belonging
damon_target struct. Depending on the future change of the offset from
the link header to the accessing field, this could also be really
dangerous, though. Still, the realistic user impact would be limited. It
would affect only test run setups.
Fix it by testing if the number of regions was also changed as expected
and exit early for the failure.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-3-sj@kernel.org
Link: https://lore.kernel.org/20260714142352.100478-1-sj@kernel.org [1]
Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/damon: fix uninitialized DAMOS field and kunit exec
expectation bugs".
Fix a few Sashiko-found unurgent bugs. Patch 1 fixes use of uninitialized
damos->last_applied field. Patches 2-7 fix DAMON kunit tests that do
invalid memory access under test failures.
The bugs are better to be fixed and eventually merged into stable@ kernel.
That said, the fixes are arguably not urgent. Patch 1 only introduces
negligible DAMOS efficiency degradation in occasional cases. Kunit fixes
could introduce quite bad consequences but those are test code that affect
only test run setups.
This patch (of 7):
Multiple DAMON regions could exist across a folio. If they fulfill the
condition to apply a DAMOS scheme, the scheme could be applied multiple
times to the folio. To avoid this, each DAMOS scheme stores the folio
that the scheme was applied to last time in the damos->last_applied field
and skips repeatedly applying the same scheme to the same folio.
The field is being used without initialization, though. Hence, the
mechanism could wrongly skip applying a scheme to a folio at the very
first time of DAMOS run.
The user impact is trivial. DAMON might unexpectedly skip applying DAMOS
action for one folio for the first time per scheme. In the DAMON's
best-effort world, this is never a real problem. No critical consequences
such as kernel panic or memory corruption happen.
It is a clear bug, though, and the fix is straightforward. Fix the issue
by initializing the field in DAMOS scheme creation function,
damon_new_scheme().
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260718001442.87129-1-sj@kernel.org
Link: https://lore.kernel.org/20260718001442.87129-2-sj@kernel.org
Link: https://lore.kernel.org/20260714055436.120034-1-sj@kernel.org [1]
Fixes: 94ba17adaba0 ("mm/damon: avoid applying DAMOS action to same entity multiple times")
Signed-off-by: SJ Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: <stable@vger.kernel.org> # 6.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The !CONFIG_SWAP stub for swap_cluster_lock() has mismatched prototype: it
has an extra unused irq argument and uses pgoff_t instead of unsigned long
for offset. All callers are under CONFIG_SWAP so the extra parameter is
dead.
Delete the unused stub function entirely.
Link: https://lore.kernel.org/20260717071104.73467-1-hongfu.li@linux.dev
Signed-off-by: Hongfu Li <lihongfu@kylinos.cn>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Acked-by: Kairui Song <kasong@tencent.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hongfu Li <lihongfu@kylinos.cn>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use early returns to reduce indentation and improve readability.
Link: https://lore.kernel.org/20260717091347.1144789-7-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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- change unsigned long nr to const
- remove a local vec variable
Link: https://lore.kernel.org/20260720124252.1483984-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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walk_hugetlb_range() always passes a non-NULL pte, so remove the dead NULL
check. Replace the per-page iteration loop with memset() for better
performance.
Link: https://lore.kernel.org/20260717091347.1144789-6-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The swap_cache_get_folio() no longer returns shadow entries, so the
xa_is_value() check is unnecessary.
Link: https://lore.kernel.org/20260717091347.1144789-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Remove ugly casts by using the more natural kmalloc/kfree allocation, also
replace GFP_USER(pointless here) with GFP_KERNEL.
Link: https://lore.kernel.org/20260717091347.1144789-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Address David's comments
- rename mincore_pud_range to mincore_pud_entry
- change int nr to const unsigned long
- remove a local vec variable
Link: https://lore.kernel.org/20260720124151.1483820-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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