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Now that powerpc no longer uses arch_unmap() to handle VDSO unmapping,
there are no meaningful implementions left. Drop support for it entirely,
and update comments which refer to it.
Link: https://lkml.kernel.org/r/20240812082605.743814-3-mpe@ellerman.id.au
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add an optional close() callback to struct vm_special_mapping. It will be
used, by powerpc at least, to handle unmapping of the VDSO.
Although support for unmapping the VDSO was initially added for CRIU[1],
it is not desirable to guard that support behind
CONFIG_CHECKPOINT_RESTORE.
There are other known users of unmapping the VDSO which are not related to
CRIU, eg. Valgrind [2] and void-ship [3].
The powerpc arch_unmap() hook has been in place for ~9 years, with no
ifdef, so there may be other unknown users that have come to rely on
unmapping the VDSO. Even if the code was behind an ifdef, major distros
enable CHECKPOINT_RESTORE so users may not realise unmapping the VDSO
depends on that configuration option.
It's also undesirable to have such core mm behaviour behind a relatively
obscure CONFIG option.
Longer term the unmap behaviour should be standardised across
architectures, however that is complicated by the fact the VDSO pointer is
stored differently across architectures. There was a previous attempt to
unify that handling [4], which could be revived.
See [5] for further discussion.
[1]: commit 83d3f0e90c6c ("powerpc/mm: tracking vDSO remap")
[2]: https://sourceware.org/git/?p=valgrind.git;a=commit;h=3a004915a2cbdcdebafc1612427576bf3321eef5
[3]: https://github.com/insanitybit/void-ship
[4]: https://lore.kernel.org/lkml/20210611180242.711399-17-dima@arista.com/
[5]: https://lore.kernel.org/linuxppc-dev/shiq5v3jrmyi6ncwke7wgl76ojysgbhrchsk32q4lbx2hadqqc@kzyy2igem256
Link: https://lkml.kernel.org/r/20240812082605.743814-1-mpe@ellerman.id.au
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jeff Xu <jeffxu@google.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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For kmem_cache with SLAB_TYPESAFE_BY_RCU, the freeing trace stack at
calling kmem_cache_free() is more useful. While the following stack is
meaningless and provides no help:
freed by task 46 on cpu 0 at 656.840729s:
rcu_do_batch+0x1ab/0x540
nocb_cb_wait+0x8f/0x260
rcu_nocb_cb_kthread+0x25/0x80
kthread+0xd2/0x100
ret_from_fork+0x34/0x50
ret_from_fork_asm+0x1a/0x30
Link: https://lkml.kernel.org/r/20240812095517.2357-1-dtcccc@linux.alibaba.com
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Batch the HVO work, including de-HVO of the source and HVO of the
destination hugeTLB folios, to speed up demotion.
After commit bd225530a4c7 ("mm/hugetlb_vmemmap: fix race with speculative
PFN walkers"), each request of HVO or de-HVO, batched or not, invokes
synchronize_rcu() once. For example, when not batched, demoting one 1GB
hugeTLB folio to 512 2MB hugeTLB folios invokes synchronize_rcu() 513
times (1 de-HVO plus 512 HVO requests), whereas when batched, only twice
(1 de-HVO plus 1 HVO request). And the performance difference between the
two cases is significant, e.g.,
echo 2048kB >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote_size
time echo 100 >/sys/kernel/mm/hugepages/hugepages-1048576kB/demote
Before this patch:
real 8m58.158s
user 0m0.009s
sys 0m5.900s
After this patch:
real 0m0.900s
user 0m0.000s
sys 0m0.851s
Note that this patch changes the behavior of the `demote` interface when
de-HVO fails. Before, the interface aborts immediately upon failure; now,
it tries to finish an entire batch, meaning it can make extra progress if
the rest of the batch contains folios that do not need to de-HVO.
Link: https://lkml.kernel.org/r/20240812224823.3914837-1-yuzhao@google.com
Fixes: bd225530a4c7 ("mm/hugetlb_vmemmap: fix race with speculative PFN walkers")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Whoever passes a folio to __folio_batch_add_and_move() must hold a
reference, otherwise something else would already be messed up. If the
folio is referenced, it will not be freed elsewhere, so we can safely
clear the folio's lru flag. As discussed with David in [1], we should
take the reference after testing the LRU flag, not before.
Link: https://lore.kernel.org/lkml/d41865b4-d6fa-49ba-890a-921eefad27dd@redhat.com/ [1]
Link: https://lkml.kernel.org/r/1723542743-32179-1-git-send-email-yangge1116@126.com
Signed-off-by: yangge <yangge1116@126.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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To allow precise tracking of page caches accessed, add new tracepoints
that trigger when a process actually accesses them.
The ureadahead program used by ChromeOS traces the disk access of programs
as they start up at boot up. It uses mincore(2) or the
'mm_filemap_add_to_page_cache' trace event to accomplish this. It stores
this information in a "pack" file and on subsequent boots, it will read
the pack file and call readahead(2) on the information so that disk
storage can be loaded into RAM before the applications actually need it.
A problem we see is that due to the kernel's readahead algorithm that can
aggressively pull in more data than needed (to try and accomplish the same
goal) and this data is also recorded. The end result is that the pack
file contains a lot of pages on disk that are never actually used.
Calling readahead(2) on these unused pages can slow down the system boot
up times.
To solve this, add 3 new trace events, get_pages, map_pages, and fault.
These will be used to trace the pages are not only pulled in from disk,
but are actually used by the application. Only those pages will be stored
in the pack file, and this helps out the performance of boot up.
With the combination of these 3 new trace events and
mm_filemap_add_to_page_cache, we observed a reduction in the pack file by
7.3% - 20% on ChromeOS varying by device.
Link: https://lkml.kernel.org/r/20240813100312.3930505-1-takayas@chromium.org
Signed-off-by: Takaya Saeki <takayas@chromium.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Junichi Uekawa <uekawa@chromium.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This is only relevant to the two archs that support PUD dax, aka, x86_64
and ppc64. PUD THPs do not yet exist elsewhere, and hugetlb PUDs do not
count in this case.
DAX have had PUD mappings for years, but change protection path never
worked. When the path is triggered in any form (a simple test program
would be: call mprotect() on a 1G dev_dax mapping), the kernel will report
"bad pud". This patch should fix that.
The new change_huge_pud() tries to keep everything simple. For example,
it doesn't optimize write bit as that will need even more PUD helpers.
It's not too bad anyway to have one more write fault in the worst case
once for 1G range; may be a bigger thing for each PAGE_SIZE, though.
Neither does it support userfault-wp bits, as there isn't such PUD
mappings that is supported; file mappings always need a split there.
The same to TLB shootdown: the pmd path (which was for x86 only) has the
trick of using _ad() version of pmdp_invalidate*() which can avoid one
redundant TLB, but let's also leave that for later. Again, the larger the
mapping, the smaller of such effect.
There's some difference on handling "retry" for change_huge_pud() (where
it can return 0): it isn't like change_huge_pmd(), as the pmd version is
safe with all conditions handled in change_pte_range() later, thanks to
Hugh's new pte_offset_map_lock(). In short, change_pte_range() is simply
smarter. For that, change_pud_range() will need proper retry if it races
with something else when a huge PUD changed from under us.
The last thing to mention is currently the PUD path ignores the huge pte
numa counter (NUMA_HUGE_PTE_UPDATES), not only because DAX is not
applicable to NUMA, but also that it's ambiguous on its own to decide how
to account pud in this case. In one earlier version of this patchset I
proposed to remove the counter as it doesn't even look right to do the
accounting as of now [1], but then a further discussion suggests we can
leave that for later, as that doesn't block this series if we choose to
ignore that counter. That's what this patch does, by ignoring it.
When at it, touch up the comment in pgtable_split_needed() to make it
generic to either pmd or pud file THPs.
[1] https://lore.kernel.org/all/20240715192142.3241557-3-peterx@redhat.com/
[2] https://lore.kernel.org/r/added2d0-b8be-4108-82ca-1367a388d0b1@redhat.com
Link: https://lkml.kernel.org/r/20240812181225.1360970-8-peterx@redhat.com
Fixes: a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent hugepages")
Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD
zaps. It has the same logic as the PMD helper.
One thing to mention is, it might be a good idea to use page_table_check
in the future for trapping wrong setups of shadow stack pgtable entries
[1]. That is left for the future as a separate effort.
[1] https://lore.kernel.org/all/59d518698f664e07c036a5098833d7b56b953305.camel@intel.com
Link: https://lkml.kernel.org/r/20240812181225.1360970-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mprotect() does mmu notifiers in PMD levels. It's there since 2014 of
commit a5338093bfb4 ("mm: move mmu notifier call from change_protection to
change_pmd_range").
At that time, the issue was that NUMA balancing can be applied on a huge
range of VM memory, even if nothing was populated. The notification can
be avoided in this case if no valid pmd detected, which includes either
THP or a PTE pgtable page.
Now to pave way for PUD handling, this isn't enough. We need to generate
mmu notifications even on PUD entries properly. mprotect() is currently
broken on PUD (e.g., one can easily trigger kernel error with dax 1G
mappings already), this is the start to fix it.
To fix that, this patch proposes to push such notifications to the PUD
layers.
There is risk on regressing the problem Rik wanted to resolve before, but I
think it shouldn't really happen, and I still chose this solution because
of a few reasons:
1) Consider a large VM that should definitely contain more than GBs of
memory, it's highly likely that PUDs are also none. In this case there
will have no regression.
2) KVM has evolved a lot over the years to get rid of rmap walks, which
might be the major cause of the previous soft-lockup. At least TDP MMU
already got rid of rmap as long as not nested (which should be the major
use case, IIUC), then the TDP MMU pgtable walker will simply see empty VM
pgtable (e.g. EPT on x86), the invalidation of a full empty region in
most cases could be pretty fast now, comparing to 2014.
3) KVM has explicit code paths now to even give way for mmu notifiers
just like this one, e.g. in commit d02c357e5bfa ("KVM: x86/mmu: Retry
fault before acquiring mmu_lock if mapping is changing"). It'll also
avoid contentions that may also contribute to a soft-lockup.
4) Stick with PMD layer simply don't work when PUD is there... We need
one way or another to fix PUD mappings on mprotect().
Pushing it to PUD should be the safest approach as of now, e.g. there's yet
no sign of huge P4D coming on any known archs.
Link: https://lkml.kernel.org/r/20240812181225.1360970-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When non-leaf pmd accessed bits are available, MGLRU page table walks can
clear the non-leaf pmd accessed bit and ignore the accessed bit on the pte
if it's on a different node, skipping a generation update as well. If
another scan occurs on the same node as said skipped pte.
The non-leaf pmd accessed bit might remain cleared and the pte accessed
bits won't be checked. While this is sufficient for reclaim-driven aging,
where the goal is to select a reasonably cold page, the access can be
missed when aging proactively for workingset estimation of a node/memcg.
In more detail, get_pfn_folio returns NULL if the folio's nid != node
under scanning, so the page table walk skips processing of said pte. Now
the pmd_young flag on this pmd is cleared, and if none of the pte's are
accessed before another scan occurs on the folio's node, the pmd_young
check fails and the pte accessed bit is skipped.
Since force_scan disables various other optimizations, we check force_scan
to ignore the non-leaf pmd accessed bit.
Link: https://lkml.kernel.org/r/20240813163759.742675-1-yuanchu@google.com
Signed-off-by: Yuanchu Xie <yuanchu@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Lance Yang <ioworker0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In commit 21e516b913c1 ("mm: vmalloc: dump page owner info if page is
already mapped"), a BUG_ON macro was changed into an if statement, where
the compiler optimization hint introduced in the BUG_ON macro was removed
along with this change. This patch adds back the hint.
Link: https://lkml.kernel.org/r/20240814-fix_vmap_unlikely-v1-1-cd7954775f12@gmail.com
Fixes: 21e516b913c1 ("mm: vmalloc: dump page owner info if page is already mapped")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hariom Panthi <hariom1.p@samsung.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Commit c574bbe91703 ("NUMA balancing: optimize page placement for memory
tiering system") introduced a new watermark above "high" -- "promo".
Accept memory memory to the highest watermark which is WMARK_PROMO now.
Link: https://lkml.kernel.org/r/20240809114854.3745464-9-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Page isolation machinery doesn't know anything about unaccepted memory and
considers it non-free. It leads to alloc_contig_pages() failure.
Treat unaccepted memory as free and accept memory on pageblock isolation.
Once memory is accepted it becomes PageBuddy() and page isolation knows
how to deal with them.
Link: https://lkml.kernel.org/r/20240809114854.3745464-8-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Accept a given struct page and add it free list.
The help is useful for physical memory scanners that want to use free
unaccepted memory.
Link: https://lkml.kernel.org/r/20240809114854.3745464-7-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Make accept_memory() and range_contains_unaccepted_memory() take 'start'
and 'size' arguments instead of 'start' and 'end'.
Remove accept_page(), replacing it with direct calls to accept_memory().
The accept_page() name is going to be used for a different function.
Link: https://lkml.kernel.org/r/20240809114854.3745464-6-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The new page type allows physical memory scanners to detect unaccepted
memory and handle it accordingly.
The page type is serialized with zone lock.
Link: https://lkml.kernel.org/r/20240809114854.3745464-5-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently, the kernel only accepts memory in get_page_from_freelist(), but
there is another path that directly takes pages from free lists -
__alloc_page_bulk(). This function can consume all accepted memory and
will resort to __alloc_pages_noprof() if necessary.
Conditionally accepted in __alloc_pages_bulk().
The same issue may arise due to deferred page initialization. Kick the
deferred initialization machinery before abandoning the zone, as the
kernel does in get_page_from_freelist().
Link: https://lkml.kernel.org/r/20240809114854.3745464-4-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: Fix several issues with unaccepted memory", v2.
The patchset addresses several issues related to unaccepted memory.
Pacth 1/7 preparatory cleanup.
Patch 2/7 ensures that __alloc_pages_bulk() will not exhaust all
accepted memory without accepting more.
Patches 3/7-5/7 are preparations for patch 6/7, which fixes
alloc_config_page() on machines with unaccepted memory. This allows, for
example, the allocation of gigantic pages at runtime.
Patch 7/7 enables the kernel to accept memory up to the promo watermark.
This patch (of 7):
Add dummy _deferred_grow_zone() for !DEFERRED_STRUCT_PAGE_INIT and remove
#ifdefs in two places.
No functional changes.
Link: https://lkml.kernel.org/r/20240809114854.3745464-1-kirill.shutemov@linux.intel.com
Link: https://lkml.kernel.org/r/20240809114854.3745464-3-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
do_numa_page() and do_huge_pmd_numa_page() share a lot of common code. To
reduce redundancy, move common code to numa_migrate_prep() and rename the
function to numa_migrate_check() to reflect its functionality.
Now do_huge_pmd_numa_page() also checks shared folios to set TNF_SHARED
flag.
Link: https://lkml.kernel.org/r/20240809145906.1513458-4-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
At the moment memcg IDs are managed through IDR which requires external
synchronization mechanisms and makes the allocation code a bit awkward.
Let's switch to xarray and make the code simpler.
[shakeel.butt@linux.dev: fix error path in mem_cgroup_alloc(), per Dan]
Link: https://lkml.kernel.org/r/20240815155402.3630804-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20240809172618.2946790-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The unuse_pte_range() caller only wants the folio while do_swap_page()
wants both the page and the folio. Since do_swap_page() already has logic
for handling both the folio and the page, move the folio-to-page logic
there. This also lets us allocate larger folios in the SWP_SYNCHRONOUS_IO
path in future.
Link: https://lkml.kernel.org/r/20240807193734.1865400-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Nobody checks the folio error flag any more, so we can stop setting and
clearing it. Also remove the documentation suggesting to not bother
setting the error bit.
Link: https://lkml.kernel.org/r/20240807193528.1865100-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Print the elapsed time for the allocated or freed track, which can be
useful in some debugging scenarios.
Link: https://lkml.kernel.org/r/20240807025627.37419-1-qiwu.chen@transsion.com
Signed-off-by: qiwu.chen <qiwu.chen@transsion.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: chenqiwu <qiwu.chen@transsion.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
pcpu_alloc_size() was added in 7ac5c53e0073 "mm/percpu.c: introduce
pcpu_alloc_size()", which is used to get the allocated memory size in bpf.
However, pcpu_alloc_size() is no longer used in "bpf: Use c->unit_size to
select target cache during free" because its actuall allocated memory size
may change at runtime due to its slab merging mechanism. Therefore,
pcpu_alloc_size() can be removed.
Link: https://lkml.kernel.org/r/tencent_AD5C50E8D78C07A3CE539BD5F6BF39706507@qq.com
Signed-off-by: Jianhui Zhou <912460177@qq.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: JonasZhou <JonasZhou@zhaoxin.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
It is not immediately obvious, but we can move the folio->_nr_pages_mapped
update out of the loop and reduce the number of atomic ops without
affecting the stats.
The important point to realize is that only removing the last PMD mapping
will result in _nr_pages_mapped going below ENTIRELY_MAPPED, not the
individual atomic_inc_return_relaxed() calls. Concurrent races with
removal of PMD mappings should be handled as expected, just like when we
would have such races right now on a single mapcount update.
In a simple munmap() microbenchmark [1] on 1 GiB of memory backed by the
same PTE-mapped folio size (only mapped by a single process such that they
will get completely unmapped), this change results in a speedup (positive
is good) per folio size on a x86-64 Intel machine of roughly (a bit of
noise expected):
* 16 KiB: +10%
* 32 KiB: +15%
* 64 KiB: +17%
* 128 KiB: +21%
* 256 KiB: +22%
* 512 KiB: +22%
* 1024 KiB: +23%
* 2048 KiB: +27%
[1] https://gitlab.com/davidhildenbrand/scratchspace/-/blob/main/pte-mapped-folio-benchmarks.c
Link: https://lkml.kernel.org/r/20240807115515.1640951-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Introduce burst mode, which can be configured with kfence.burst=$count,
where the burst count denotes the additional successive slab allocations
to be allocated through KFENCE for each sample interval.
The idea is that this can give developers an additional knob to make
KFENCE more aggressive when debugging specific issues of systems where
either rebooting or recompiling the kernel with KASAN is not possible.
Experiment: To assess the effectiveness of the new option, we randomly
picked a recent out-of-bounds [1] and use-after-free bug [2], each with a
reproducer provided by syzbot, that initially detected these bugs with
KASAN. We then tried to reproduce the bugs with KFENCE below.
[1] Fixed by: 7c55b78818cf ("jfs: xattr: fix buffer overflow for invalid xattr")
https://syzkaller.appspot.com/bug?id=9d1b59d4718239da6f6069d3891863c25f9f24a2
[2] Fixed by: f8ad00f3fb2a ("l2tp: fix possible UAF when cleaning up tunnels")
https://syzkaller.appspot.com/bug?id=4f34adc84f4a3b080187c390eeef60611fd450e1
The following KFENCE configs were compared. A pool size of 1023 objects
was used for all configurations.
Baseline
kfence.sample_interval=100
kfence.skip_covered_thresh=75
kfence.burst=0
Aggressive
kfence.sample_interval=1
kfence.skip_covered_thresh=10
kfence.burst=0
AggressiveBurst
kfence.sample_interval=1
kfence.skip_covered_thresh=10
kfence.burst=1000
Each reproducer was run 10 times (after a fresh reboot), with the
following detection counts for each KFENCE config:
| Detection Count out of 10 |
| OOB [1] | UAF [2] |
------------------+-------------+-------------+
Default | 0/10 | 0/10 |
Aggressive | 0/10 | 0/10 |
AggressiveBurst | 8/10 | 8/10 |
With the Default and even the Aggressive configs the results are
unsurprising, given KFENCE has not been designed for deterministic bug
detection of small test cases.
However, when enabling burst mode with relatively large burst count,
KFENCE can start to detect heap memory-safety bugs even in simpler test
cases with high probability (in the above cases with ~80% probability).
Link: https://lkml.kernel.org/r/20240805124203.2692278-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There is a (harmless) type confusion in lock_vma_under_rcu(): After
vma_start_read(), we have taken the VMA lock but don't know yet whether
the VMA has already been detached and scheduled for RCU freeing. At this
point, ->vm_start and ->vm_end are accessed.
vm_area_struct contains a union such that ->vm_rcu uses the same memory as
->vm_start and ->vm_end; so accessing ->vm_start and ->vm_end of a
detached VMA is illegal and leads to type confusion between union members.
Fix it by reordering the vma->detached check above the address checks, and
document the rules for RCU readers accessing VMAs.
This will probably change the number of observed VMA_LOCK_MISS events
(since previously, trying to access a detached VMA whose ->vm_rcu has been
scheduled would bail out when checking the fault address against the
rcu_head members reinterpreted as VMA bounds).
Link: https://lkml.kernel.org/r/20240805-fix-vma-lock-type-confusion-v1-1-9f25443a9a71@google.com
Fixes: 50ee32537206 ("mm: introduce lock_vma_under_rcu to be used from arch-specific code")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently, there are a couple of issues with our disk swapin tracking for
dynamic zswap shrinker heuristics:
1. We only increment the swapin counter on pivot pages. This means we
are not taking into account pages that also need to be swapped in,
but are already taken care of as part of the readahead window.
2. We are also incrementing when the pages are read from the zswap pool,
which is inaccurate.
This patch rectifies these issues by incrementing the counter whenever we
need to perform a non-zswap read. Note that we are slightly overcounting,
as a page might be read into memory by the readahead algorithm even though
it will not be neeeded by users - however, this is an acceptable
inaccuracy, as the readahead logic itself will adapt to these kind of
scenarios.
To test this change, I built the kernel under a cgroup with its memory.max
set to 2 GB:
real: 236.66s
user: 4286.06s
sys: 652.86s
swapins: 81552
For comparison, with just the new second chance algorithm, the build time
is as follows:
real: 244.85s
user: 4327.22s
sys: 664.39s
swapins: 94663
Without neither:
real: 263.89s
user: 4318.11s
sys: 673.29s
swapins: 227300.5
(average over 5 runs)
With this change, the kernel CPU time reduces by a further 1.7%, and the
real time is reduced by another 3.3%, compared to just the second chance
algorithm by itself. The swapins count also reduces by another 13.85%.
Combinng the two changes, we reduce the real time by 10.32%, kernel CPU
time by 3%, and number of swapins by 64.12%.
To gauge the new scheme's ability to offload cold data, I ran another
benchmark, in which the kernel was built under a cgroup with memory.max
set to 3 GB, but with 0.5 GB worth of cold data allocated before each
build (in a shmem file).
Under the old scheme:
real: 197.18s
user: 4365.08s
sys: 289.02s
zswpwb: 72115.2
Under the new scheme:
real: 195.8s
user: 4362.25s
sys: 290.14s
zswpwb: 87277.8
(average over 5 runs)
Notice that we actually observe a 21% increase in the number of written
back pages - so the new scheme is just as good, if not better at
offloading pages from the zswap pool when they are cold. Build time
reduces by around 0.7% as a result.
[nphamcs@gmail.com: squeeze a comment into a single line]
Link: https://lkml.kernel.org/r/20240806004518.3183562-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20240805232243.2896283-3-nphamcs@gmail.com
Fixes: b5ba474f3f51 ("zswap: shrink zswap pool based on memory pressure")
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Takero Funaki <flintglass@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "improving dynamic zswap shrinker protection scheme", v3.
When experimenting with the memory-pressure based (i.e "dynamic") zswap
shrinker in production, we observed a sharp increase in the number of
swapins, which led to performance regression. We were able to trace this
regression to the following problems with the shrinker's warm pages
protection scheme:
1. The protection decays way too rapidly, and the decaying is coupled with
zswap stores, leading to anomalous patterns, in which a small batch of
zswap stores effectively erase all the protection in place for the
warmer pages in the zswap LRU.
This observation has also been corroborated upstream by Takero Funaki
(in [1]).
2. We inaccurately track the number of swapped in pages, missing the
non-pivot pages that are part of the readahead window, while counting
the pages that are found in the zswap pool.
To alleviate these two issues, this patch series improve the dynamic zswap
shrinker in the following manner:
1. Replace the protection size tracking scheme with a second chance
algorithm. This new scheme removes the need for haphazard stats
decaying, and automatically adjusts the pace of pages aging with memory
pressure, and writeback rate with pool activities: slowing down when
the pool is dominated with zswpouts, and speeding up when the pool is
dominated with stale entries.
2. Fix the tracking of the number of swapins to take into account
non-pivot pages in the readahead window.
With these two changes in place, in a kernel-building benchmark without
any cold data added, the number of swapins is reduced by 64.12%. This
translate to a 10.32% reduction in build time. We also observe a 3%
reduction in kernel CPU time.
In another benchmark, with cold data added (to gauge the new algorithm's
ability to offload cold data), the new second chance scheme outperforms
the old protection scheme by around 0.7%, and actually written back around
21% more pages to backing swap device. So the new scheme is just as good,
if not even better than the old scheme on this front as well.
[1]: https://lore.kernel.org/linux-mm/CAPpodddcGsK=0Xczfuk8usgZ47xeyf4ZjiofdT+ujiyz6V2pFQ@mail.gmail.com/
This patch (of 2):
Current zswap shrinker's heuristics to prevent overshrinking is brittle
and inaccurate, specifically in the way we decay the protection size (i.e
making pages in the zswap LRU eligible for reclaim).
We currently decay protection aggressively in zswap_lru_add() calls. This
leads to the following unfortunate effect: when a new batch of pages enter
zswap, the protection size rapidly decays to below 25% of the zswap LRU
size, which is way too low.
We have observed this effect in production, when experimenting with the
zswap shrinker: the rate of shrinking shoots up massively right after a
new batch of zswap stores. This is somewhat the opposite of what we want
originally - when new pages enter zswap, we want to protect both these new
pages AND the pages that are already protected in the zswap LRU.
Replace existing heuristics with a second chance algorithm
1. When a new zswap entry is stored in the zswap pool, its referenced
bit is set.
2. When the zswap shrinker encounters a zswap entry with the referenced
bit set, give it a second chance - only flips the referenced bit and
rotate it in the LRU.
3. If the shrinker encounters the entry again, this time with its
referenced bit unset, then it can reclaim the entry.
In this manner, the aging of the pages in the zswap LRUs are decoupled
from zswap stores, and picks up the pace with increasing memory pressure
(which is what we want).
The second chance scheme allows us to modulate the writeback rate based on
recent pool activities. Entries that recently entered the pool will be
protected, so if the pool is dominated by such entries the writeback rate
will reduce proportionally, protecting the workload's workingset.On the
other hand, stale entries will be written back quickly, which increases
the effective writeback rate.
The referenced bit is added at the hole after the `length` field of struct
zswap_entry, so there is no extra space overhead for this algorithm.
We will still maintain the count of swapins, which is consumed and
subtracted from the lru size in zswap_shrinker_count(), to further
penalize past overshrinking that led to disk swapins. The idea is that
had we considered this many more pages in the LRU active/protected, they
would not have been written back and we would not have had to swapped them
in.
To test this new heuristics, I built the kernel under a cgroup with
memory.max set to 2G, on a host with 36 cores:
With the old shrinker:
real: 263.89s
user: 4318.11s
sys: 673.29s
swapins: 227300.5
With the second chance algorithm:
real: 244.85s
user: 4327.22s
sys: 664.39s
swapins: 94663
(average over 5 runs)
We observe an 1.3% reduction in kernel CPU usage, and around 7.2%
reduction in real time. Note that the number of swapped in pages
dropped by 58%.
[nphamcs@gmail.com: fix a small mistake in the referenced bit documentation]
Link: https://lkml.kernel.org/r/20240806003403.3142387-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20240805232243.2896283-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20240805232243.2896283-2-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Takero Funaki <flintglass@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The generic mmap_base code tries to leave a gap between the top of the
stack and the mmap base address, but enforces a minimum gap size (MIN_GAP)
of 128MB, which is too large on some setups. In particular, on arm tasks
without ADDR_LIMIT_32BIT, the STACK_TOP value is less than 128MB, so it's
impossible to fit such a gap in.
Only enforce this minimum if MIN_GAP < MAX_GAP, as we'd prefer to honour
MAX_GAP, which is defined proportionally, so scales better and always
leaves us with both _some_ stack space and some room for mmap.
This fixes the usercopy KUnit test suite on 32-bit arm, as it doesn't set
any personality flags so gets the default (in this case 26-bit) task size.
This test can be run with: ./tools/testing/kunit/kunit.py run --arch arm
usercopy --make_options LLVM=1
Link: https://lkml.kernel.org/r/20240803074642.1849623-2-davidgow@google.com
Fixes: dba79c3df4a2 ("arm: use generic mmap top-down layout and brk randomization")
Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The header files linux/bug.h is included twice in vma_internal.h, so one
inclusion of each can be removed.
Link: https://lkml.kernel.org/r/20240802060216.24591-1-yang.lee@linux.alibaba.com
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9636
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's simplify by reusing folio_walk. Keep the existing behavior by
handling migration entries and zeropages.
Link: https://lkml.kernel.org/r/20240802155524.517137-12-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
All users are gone, let's remove it and any leftovers in comments. We'll
leave any FOLL/follow_page_() naming cleanups as future work.
Link: https://lkml.kernel.org/r/20240802155524.517137-11-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's remove yet another follow_page() user. Note that we have to do the
split without holding the PTL, after folio_walk_end(). We don't care
about losing the secretmem check in follow_page().
[david@redhat.com: teach can_split_folio() that we are not holding an additional reference]
Link: https://lkml.kernel.org/r/c75d1c6c-8ea6-424f-853c-1ccda6c77ba2@redhat.com
Link: https://lkml.kernel.org/r/20240802155524.517137-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's use folio_walk instead, for example avoiding taking temporary folio
references if the folio does obviously not even apply and getting rid of
one more follow_page() user. We cannot move all handling under the PTL,
so leave the rmap handling (which implies an allocation) out.
Note that zeropages obviously don't apply: old code could just have
specified FOLL_DUMP. Further, we don't care about losing the secretmem
check in follow_page(): these are never anon pages and
vma_ksm_compatible() would never consider secretmem vmas (VM_SHARED |
VM_MAYSHARE must be set for secretmem, see secretmem_mmap()).
Link: https://lkml.kernel.org/r/20240802155524.517137-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's use folio_walk instead, for example avoiding taking temporary folio
references if the folio does not even apply and getting rid of one more
follow_page() user.
Note that zeropages obviously don't apply: old code could just have
specified FOLL_DUMP. Anon folios are never secretmem, so we don't care
about losing the check in follow_page().
Link: https://lkml.kernel.org/r/20240802155524.517137-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's use folio_walk instead, so we can avoid taking a folio reference
when we won't even be trying to migrate the folio and to get rid of
another follow_page()/FOLL_DUMP user. Use FW_ZEROPAGE so we can return
"-EFAULT" for it as documented.
We now perform the folio_likely_mapped_shared() check under PTL, which is
what we want: relying on the mapcount and friends after dropping the PTL
does not make too much sense, as the page can get unmapped concurrently
from this process.
Further, we perform the folio isolation under PTL, similar to how we
handle it for MADV_PAGEOUT.
The possible return values for follow_page() were confusing, especially
with FOLL_DUMP set. We'll handle it like documented in the man page:
* -EFAULT: This is a zero page or the memory area is not mapped by the
process.
* -ENOENT: The page is not present.
We'll keep setting -ENOENT for ZONE_DEVICE. Maybe not the right thing to
do, but it likely doesn't really matter (just like for weird devmap,
whereby we fake "not present").
The other errros are left as is, and match the documentation in the man
page.
While at it, rename add_page_for_migration() to add_folio_for_migration().
We'll lose the "secretmem" check, but that shouldn't really matter because
these folios cannot ever be migrated. Should vma_migratable() refuse
these VMAs? Maybe.
Link: https://lkml.kernel.org/r/20240802155524.517137-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's use folio_walk instead, so we can avoid taking a folio reference
just to read the nid and get rid of another follow_page()/FOLL_DUMP user.
Use FW_ZEROPAGE so we can return "-EFAULT" for it as documented.
The possible return values for follow_page() were confusing, especially
with FOLL_DUMP set. We'll handle it like documented in the man page:
* -EFAULT: This is a zero page or the memory area is not mapped by the
process.
* -ENOENT: The page is not present.
We'll keep setting -ENOENT for ZONE_DEVICE. Maybe not the right thing to
do, but it likely doesn't really matter (just like for weird devmap,
whereby we fake "not present").
Note that the other errors (-EACCESS, -EBUSY, -EIO, -EINVAL, -ENOMEM) so
far only applied when actually moving pages, not when only querying stats.
We'll effectively drop the "secretmem" check we had in follow_page(), but
that shouldn't really matter here, we're not accessing folio/page content
after all.
Link: https://lkml.kernel.org/r/20240802155524.517137-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We want to get rid of follow_page(), and have a more reasonable way to
just lookup a folio mapped at a certain address, perform some checks while
still under PTL, and then only conditionally grab a folio reference if
really required.
Further, we might want to get rid of some walk_page_range*() users that
really only want to temporarily lookup a single folio at a single address.
So let's add a new page table walker that does exactly that, similarly to
GUP also being able to walk hugetlb VMAs.
Add folio_walk_end() as a macro for now: the compiler is not easy to
please with the pte_unmap()->kunmap_local().
Note that one difference between follow_page() and get_user_pages(1) is
that follow_page() will not trigger faults to get something mapped. So
folio_walk is at least currently not a replacement for get_user_pages(1),
but could likely be extended/reused to achieve something similar in the
future.
Link: https://lkml.kernel.org/r/20240802155524.517137-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: replace follow_page() by folio_walk".
Looking into a way of moving the last folio_likely_mapped_shared() call in
add_folio_for_migration() under the PTL, I found myself removing
follow_page(). This paves the way for cleaning up all the FOLL_, follow_*
terminology to just be called "GUP" nowadays.
The new page table walker will lookup a mapped folio and return to the
caller with the PTL held, such that the folio cannot get unmapped
concurrently. Callers can then conditionally decide whether they really
want to take a short-term folio reference or whether the can simply unlock
the PTL and be done with it.
folio_walk is similar to page_vma_mapped_walk(), except that we don't know
the folio we want to walk to and that we are only walking to exactly one
PTE/PMD/PUD.
folio_walk provides access to the pte/pmd/pud (and the referenced folio
page because things like KSM need that), however, as part of this series
no page table modifications are performed by users.
We might be able to convert some other walk_page_range() users that really
only walk to one address, such as DAMON with
damon_mkold_ops/damon_young_ops. It might make sense to extend folio_walk
in the future to optionally fault in a folio (if applicable), such that we
can replace some get_user_pages() users that really only want to lookup a
single page/folio under PTL without unconditionally grabbing a folio
reference.
I have plans to extend the approach to a range walker that will try
batching various page table entries (not just folio pages) to be a better
replace for walk_page_range() -- and users will be able to opt in which
type of page table entries they want to process -- but that will require
more work and more thoughts.
KSM seems to work just fine (ksm_functional_tests selftests) and
move_pages seems to work (migration selftest). I tested the leaf
implementation excessively using various hugetlb sizes (64K, 2M, 32M, 1G)
on arm64 using move_pages and did some more testing on x86-64. Cross
compiled on a bunch of architectures.
This patch (of 11):
We want to make use of vm_normal_page_pmd() in generic page table walking
code where we might walk hugetlb folios that are mapped by PMDs even
without CONFIG_TRANSPARENT_HUGEPAGE.
So let's expose vm_normal_page_pmd() + vm_normal_folio_pmd() with
CONFIG_PGTABLE_HAS_HUGE_LEAVES.
Link: https://lkml.kernel.org/r/20240802155524.517137-1-david@redhat.com
Link: https://lkml.kernel.org/r/20240802155524.517137-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Print the promo watermark in zoneinfo just like other watermarks. This
helps users check and verify all the watermarks are appropriate.
Link: https://lkml.kernel.org/r/20240801232548.36604-3-kaiyang2@cs.cmu.edu
Signed-off-by: Kaiyang Zhao <kaiyang2@cs.cmu.edu>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: print the promo watermark in zoneinfo", v2.
This patch (of 2):
Define promo_wmark_pages and convert current call sites of wmark_pages
with fixed WMARK_PROMO to using it instead.
Link: https://lkml.kernel.org/r/20240801232548.36604-1-kaiyang2@cs.cmu.edu
Link: https://lkml.kernel.org/r/20240801232548.36604-2-kaiyang2@cs.cmu.edu
Signed-off-by: Kaiyang Zhao <kaiyang2@cs.cmu.edu>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently in migrate_balanced_pgdat(), ALLOC_CMA flag is not passed when
checking watermark on the migration target node. This does not match the
gfp in alloc_misplaced_dst_folio() which allows allocation from CMA.
This causes promotion failures when there are a lot of available CMA
memory in the system.
Therefore, we change the alloc_flags passed to zone_watermark_ok() in
migrate_balanced_pgdat().
Link: https://lkml.kernel.org/r/20240801180456.25927-1-kaiyang2@cs.cmu.edu
Signed-off-by: Kaiyang Zhao <kaiyang2@cs.cmu.edu>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This patch fixes the zswap global shrinker, which did not shrink the zpool
as expected.
The issue addressed is that shrink_worker() did not distinguish between
unexpected errors and expected errors, such as failed writeback from an
empty memcg. The shrinker would stop shrinking after iterating through
the memcg tree 16 times, even if there was only one empty memcg.
With this patch, the shrinker no longer considers encountering an empty
memcg, encountering a memcg with writeback disabled, or reaching the end
of a memcg tree walk as a failure, as long as there are memcgs that are
candidates for writeback. Systems with one or more empty memcgs will now
observe significantly higher zswap writeback activity after the zswap pool
limit is hit.
To avoid an infinite loop when there are no writeback candidates, this
patch tracks writeback attempts during memcg tree walks and limits reties
if no writeback candidates are found.
To handle the empty memcg case, the helper function shrink_memcg() is
modified to check if the memcg is empty and then return -ENOENT.
Link: https://lkml.kernel.org/r/20240731004918.33182-3-flintglass@gmail.com
Fixes: a65b0e7607cc ("zswap: make shrinking memcg-aware")
Signed-off-by: Takero Funaki <flintglass@gmail.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: zswap: fixes for global shrinker", v5.
This series addresses issues in the zswap global shrinker that could not
shrink stored pages. With this series, the shrinker continues to shrink
pages until it reaches the accept threshold more reliably, gives much
higher writeback when the zswap pool limit is hit.
This patch (of 2):
This patch fixes an issue where the zswap global shrinker stopped
iterating through the memcg tree.
The problem was that shrink_worker() would restart iterating memcg tree
from the tree root, considering an offline memcg as a failure, and abort
shrinking after encountering the same offline memcg 16 times even if there
is only one offline memcg. After this change, an offline memcg in the
tree is no longer considered a failure. This allows the shrinker to
continue shrinking the other online memcgs regardless of whether an
offline memcg exists, gives higher zswap writeback activity.
To avoid holding refcount of offline memcg encountered during the memcg
tree walking, shrink_worker() must continue iterating to release the
offline memcg to ensure the next memcg stored in the cursor is online.
The offline memcg cleaner has also been changed to avoid the same issue.
When the next memcg of the offlined memcg is also offline, the refcount
stored in the iteration cursor was held until the next shrink_worker()
run. The cleaner must release the offline memcg recursively.
[yosryahmed@google.com: make critical section more obvious, unify comments]
Link: https://lkml.kernel.org/r/CAJD7tkaScz+SbB90Q1d5mMD70UfM2a-J2zhXDT9sePR7Qap45Q@mail.gmail.com
Link: https://lkml.kernel.org/r/20240731004918.33182-1-flintglass@gmail.com
Link: https://lkml.kernel.org/r/20240731004918.33182-2-flintglass@gmail.com
Fixes: a65b0e7607cc ("zswap: make shrinking memcg-aware")
Signed-off-by: Takero Funaki <flintglass@gmail.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
It should be checked by filemap_get_folio() if SWAP_HAS_CACHE was
marked while reading a share swap page. It would re-allocate a folio
if the swap cache was not ready now. We save the new folio to avoid
page allocating again.
Link: https://lkml.kernel.org/r/20240731133101.GA2096752@bytedance
Signed-off-by: Zhaoyu Liu <liuzhaoyu.zackary@bytedance.com>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's simplify and reduce code indentation. In the RMAP_LEVEL_PTE case,
we already check for nr when computing partially_mapped.
For RMAP_LEVEL_PMD, it's a bit more confusing. Likely, we don't need the
"nr" check, but we could have "nr < nr_pmdmapped" also if we stumbled into
the "/* Raced ahead of another remove and an add? */" case. So let's
simply move the nr check in there.
Note that partially_mapped is always false for small folios.
No functional change intended.
Link: https://lkml.kernel.org/r/20240710214350.147864-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
After commit 73db3abdca58 ("init/modpost: conditionally check section
mismatch to __meminit*"), we can get rid of __ref annotations.
Link: https://lkml.kernel.org/r/20240726010157.6177-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
support large folios
Right now, swapcache_prepare() and swapcache_clear() supports one entry
only, to support large folios, we need to handle multiple swap entries.
To optimize stack usage, we iterate twice in __swap_duplicate(): the first
time to verify that all entries are valid, and the second time to apply
the modifications to the entries.
Currently, we're using nr=1 for the existing users.
[v-songbaohua@oppo.com: clarify swap_count_continued and improve readability for __swap_duplicate]
Link: https://lkml.kernel.org/r/20240802071817.47081-1-21cnbao@gmail.com
Link: https://lkml.kernel.org/r/20240730071339.107447-2-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Gao Xiang <xiang@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Compiling z3fold.c results in several sparse warnings:
z3fold.c:797:21: warning: incorrect type in initializer (different address spaces)
z3fold.c:797:21: expected void const [noderef] __percpu *__vpp_verify
z3fold.c:797:21: got struct list_head *
z3fold.c:852:37: warning: incorrect type in initializer (different address spaces)
z3fold.c:852:37: expected void const [noderef] __percpu *__vpp_verify
z3fold.c:852:37: got struct list_head *
z3fold.c:924:25: warning: incorrect type in assignment (different address spaces)
z3fold.c:924:25: expected struct list_head *unbuddied
z3fold.c:924:25: got void [noderef] __percpu *_res
z3fold.c:930:33: warning: incorrect type in initializer (different address spaces)
z3fold.c:930:33: expected void const [noderef] __percpu *__vpp_verify
z3fold.c:930:33: got struct list_head *
z3fold.c:949:25: warning: incorrect type in argument 1 (different address spaces)
z3fold.c:949:25: expected void [noderef] __percpu *__pdata
z3fold.c:949:25: got struct list_head *unbuddied
z3fold.c:979:25: warning: incorrect type in argument 1 (different address spaces)
z3fold.c:979:25: expected void [noderef] __percpu *__pdata
z3fold.c:979:25: got struct list_head *unbuddied
Add __percpu annotation to *unbuddied pointer to fix these warnings.
Link: https://lkml.kernel.org/r/20240730123445.5875-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
