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+ mm-fix-folio_expected_ref_count-when-pg_private_2.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm: fix folio_expected_ref_count() when PG_private_2 has been added to the -mm mm-new branch. Its filename is mm-fix-folio_expected_ref_count-when-pg_private_2.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm: fix folio_expected_ref_count() when PG_private_2 Date: Sun, 31 Aug 2025 02:01:16 -0700 (PDT) 6.16's folio_expected_ref_count() is forgetting the PG_private_2 flag, which (like PG_private, but not in addition to PG_private) counts for 1 more reference: it needs to be using folio_has_private() in place of folio_test_private(). But this went wrong earlier: folio_expected_ref_count() was based on (and replaced) mm/migrate.c's folio_expected_refs(), which has been using folio_test_private() since 6.0 converted to folios(): before that, expected_page_refs() was correctly using page_has_private(). Just a few filesystems are still using PG_private_2 a.k.a. PG_fscache. Potentially, this fix re-enables page migration on their folios; but it would not be surprising to learn that in practice those folios are not migratable for other reasons. Link: https://lkml.kernel.org/r/f91ee36e-a8cb-e3a4-c23b-524ff3848da7@google.com Fixes: 86ebd50224c0 ("mm: add folio_expected_ref_count() for reference count calculation") Fixes: 108ca8358139 ("mm/migrate: Convert expected_page_refs() to folio_expected_refs()") Signed-off-by: Hugh Dickins <hughd(a)google.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: Will Deacon <will(a)kernel.org> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/mm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/include/linux/mm.h~mm-fix-folio_expected_ref_count-when-pg_private_2 +++ a/include/linux/mm.h @@ -2234,8 +2234,8 @@ static inline int folio_expected_ref_cou } else { /* One reference per page from the pagecache. */ ref_count += !!folio->mapping << order; - /* One reference from PG_private. */ - ref_count += folio_test_private(folio); + /* One reference from PG_private or PG_private_2. */ + ref_count += folio_has_private(folio); } /* One reference per page table mapping. */ _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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PCI: dwc: Ensure that dw_pcie_wait_for_link() waits 100 ms after link up

by Marek Vasut

Please backport the following commit into Linux v5.4 and newer stable releases: 80dc18a0cba8dea42614f021b20a04354b213d86 The backport will likely depend on macro rename commit: 817f989700fddefa56e5e443e7d138018ca6709d This part of commit description clarifies why this is a fix: " As per PCIe r6.0, sec 6.6.1, a Downstream Port that supports Link speeds greater than 5.0 GT/s, software must wait a minimum of 100 ms after Link training completes before sending a Configuration Request. " In practice, this makes detection of PCIe Gen3 and Gen4 SSDs reliable on Renesas R-Car V4H SoC. Without this commit, the SSDs sporadically do not get detected, or sometimes they link up in Gen1 mode. This fixes commit 886bc5ceb5cc ("PCI: designware: Add generic dw_pcie_wait_for_link()") which is in v4.5-rc1-4-g886bc5ceb5cc3 , so I think this fix should be backported to all currently maintained stable releases, i.e. v5.4+ . Thank you -- Best regards, Marek Vasut

1 week, 1 day

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+ mm-folio_may_be_cached-unless-folio_test_large.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm: folio_may_be_cached() unless folio_test_large() has been added to the -mm mm-new branch. Its filename is mm-folio_may_be_cached-unless-folio_test_large.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm: folio_may_be_cached() unless folio_test_large() Date: Sun, 31 Aug 2025 02:16:25 -0700 (PDT) mm/swap.c and mm/mlock.c agree to drain any per-CPU batch as soon as a large folio is added: so collect_longterm_unpinnable_folios() just wastes effort when calling lru_add_drain_all() on a large folio. But although there is good reason not to batch up PMD-sized folios, we might well benefit from batching a small number of low-order mTHPs (though unclear how that "small number" limitation will be implemented). So ask if folio_may_be_cached() rather than !folio_test_large(), to insulate those particular checks from future change. Name preferred to "folio_is_batchable" because large folios can well be put on a batch: it's just the per-CPU LRU caches, drained much later, which need care. Marked for stable, to counter the increase in lru_add_drain_all()s from "mm/gup: check ref_count instead of lru before migration". Link: https://lkml.kernel.org/r/861c061c-51cd-b940-49df-9f55e1fee2c8@google.com Signed-off-by: Hugh Dickins <hughd(a)google.com> Suggested-by: David Hildenbrand <david(a)redhat.com> Cc: <stable(a)vger.kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: Will Deacon <will(a)kernel.org> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/swap.h | 10 ++++++++++ mm/gup.c | 5 +++-- mm/mlock.c | 6 +++--- mm/swap.c | 2 +- 4 files changed, 17 insertions(+), 6 deletions(-) --- a/include/linux/swap.h~mm-folio_may_be_cached-unless-folio_test_large +++ a/include/linux/swap.h @@ -381,6 +381,16 @@ void folio_add_lru_vma(struct folio *, s void mark_page_accessed(struct page *); void folio_mark_accessed(struct folio *); +static inline bool folio_may_be_cached(struct folio *folio) +{ + /* + * Holding PMD-sized folios in per-CPU LRU cache unbalances accounting. + * Holding small numbers of low-order mTHP folios in per-CPU LRU cache + * will be sensible, but nobody has implemented and tested that yet. + */ + return !folio_test_large(folio); +} + extern atomic_t lru_disable_count; static inline bool lru_cache_disabled(void) --- a/mm/gup.c~mm-folio_may_be_cached-unless-folio_test_large +++ a/mm/gup.c @@ -2309,8 +2309,9 @@ static unsigned long collect_longterm_un continue; } - if (drain_allow && folio_ref_count(folio) != - folio_expected_ref_count(folio) + 1) { + if (drain_allow && folio_may_be_cached(folio) && + folio_ref_count(folio) != + folio_expected_ref_count(folio) + 1) { lru_add_drain_all(); drain_allow = false; } --- a/mm/mlock.c~mm-folio_may_be_cached-unless-folio_test_large +++ a/mm/mlock.c @@ -255,7 +255,7 @@ void mlock_folio(struct folio *folio) folio_get(folio); if (!folio_batch_add(fbatch, mlock_lru(folio)) || - folio_test_large(folio) || lru_cache_disabled()) + !folio_may_be_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock); } @@ -278,7 +278,7 @@ void mlock_new_folio(struct folio *folio folio_get(folio); if (!folio_batch_add(fbatch, mlock_new(folio)) || - folio_test_large(folio) || lru_cache_disabled()) + !folio_may_be_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock); } @@ -299,7 +299,7 @@ void munlock_folio(struct folio *folio) */ folio_get(folio); if (!folio_batch_add(fbatch, folio) || - folio_test_large(folio) || lru_cache_disabled()) + !folio_may_be_cached(folio) || lru_cache_disabled()) mlock_folio_batch(fbatch); local_unlock(&mlock_fbatch.lock); } --- a/mm/swap.c~mm-folio_may_be_cached-unless-folio_test_large +++ a/mm/swap.c @@ -192,7 +192,7 @@ static void __folio_batch_add_and_move(s local_lock(&cpu_fbatches.lock); if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || - folio_test_large(folio) || lru_cache_disabled()) + !folio_may_be_cached(folio) || lru_cache_disabled()) folio_batch_move_lru(this_cpu_ptr(fbatch), move_fn); if (disable_irq) _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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+ mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm: Revert "mm: vmscan.c: fix OOM on swap stress test" has been added to the -mm mm-new branch. Its filename is mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm: Revert "mm: vmscan.c: fix OOM on swap stress test" Date: Sun, 31 Aug 2025 02:13:55 -0700 (PDT) This reverts commit 0885ef4705607936fc36a38fd74356e1c465b023: that was a fix to the reverted 33dfe9204f29b415bbc0abb1a50642d1ba94f5e9. Link: https://lkml.kernel.org/r/bd440614-3d2c-31d6-1b8f-9635c69cef7c@google.com Fixes: 0885ef470560 ("mm: vmscan.c: fix OOM on swap stress test") Signed-off-by: Hugh Dickins <hughd(a)google.com> Cc: <stable(a)vger.kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: Will Deacon <will(a)kernel.org> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/vmscan.c~mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test +++ a/mm/vmscan.c @@ -4500,7 +4500,7 @@ static bool sort_folio(struct lruvec *lr } /* ineligible */ - if (!folio_test_lru(folio) || zone > sc->reclaim_idx) { + if (zone > sc->reclaim_idx) { gen = folio_inc_gen(lruvec, folio, false); list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]); return true; _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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+ mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm: Revert "mm/gup: clear the LRU flag of a page before adding to LRU batch" has been added to the -mm mm-new branch. Its filename is mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm: Revert "mm/gup: clear the LRU flag of a page before adding to LRU batch" Date: Sun, 31 Aug 2025 02:11:33 -0700 (PDT) This reverts commit 33dfe9204f29b415bbc0abb1a50642d1ba94f5e9: now that collect_longterm_unpinnable_folios() is checking ref_count instead of lru, and mlock/munlock do not participate in the revised LRU flag clearing, those changes are misleading, and enlarge the window during which mlock/munlock may miss an mlock_count update. It is possible (I'd hesitate to claim probable) that the greater likelihood of missed mlock_count updates would explain the "Realtime threads delayed due to kcompactd0" observed on 6.12 in the Link below. If that is the case, this reversion will help; but a complete solution needs also a further patch, beyond the scope of this series. Included some 80-column cleanup around folio_batch_add_and_move(). The role of folio_test_clear_lru() (before taking per-memcg lru_lock) is questionable since 6.13 removed mem_cgroup_move_account() etc; but perhaps there are still some races which need it - not examined here. Link: https://lore.kernel.org/linux-mm/DU0PR01MB10385345F7153F334100981888259A@DU… Link: https://lkml.kernel.org/r/0215a42b-99cd-612a-95f7-56f8251d99ef@google.com Fixes: 33dfe9204f29 ("mm/gup: clear the LRU flag of a page before adding to LRU batch") Signed-off-by: Hugh Dickins <hughd(a)google.com> Cc: <stable(a)vger.kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: Will Deacon <will(a)kernel.org> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/swap.c | 50 ++++++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 24 deletions(-) --- a/mm/swap.c~mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch +++ a/mm/swap.c @@ -164,6 +164,10 @@ static void folio_batch_move_lru(struct for (i = 0; i < folio_batch_count(fbatch); i++) { struct folio *folio = fbatch->folios[i]; + /* block memcg migration while the folio moves between lru */ + if (move_fn != lru_add && !folio_test_clear_lru(folio)) + continue; + folio_lruvec_relock_irqsave(folio, &lruvec, &flags); move_fn(lruvec, folio); @@ -176,14 +180,10 @@ static void folio_batch_move_lru(struct } static void __folio_batch_add_and_move(struct folio_batch __percpu *fbatch, - struct folio *folio, move_fn_t move_fn, - bool on_lru, bool disable_irq) + struct folio *folio, move_fn_t move_fn, bool disable_irq) { unsigned long flags; - if (on_lru && !folio_test_clear_lru(folio)) - return; - folio_get(folio); if (disable_irq) @@ -191,8 +191,8 @@ static void __folio_batch_add_and_move(s else local_lock(&cpu_fbatches.lock); - if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || folio_test_large(folio) || - lru_cache_disabled()) + if (!folio_batch_add(this_cpu_ptr(fbatch), folio) || + folio_test_large(folio) || lru_cache_disabled()) folio_batch_move_lru(this_cpu_ptr(fbatch), move_fn); if (disable_irq) @@ -201,13 +201,13 @@ static void __folio_batch_add_and_move(s local_unlock(&cpu_fbatches.lock); } -#define folio_batch_add_and_move(folio, op, on_lru) \ - __folio_batch_add_and_move( \ - &cpu_fbatches.op, \ - folio, \ - op, \ - on_lru, \ - offsetof(struct cpu_fbatches, op) >= offsetof(struct cpu_fbatches, lock_irq) \ +#define folio_batch_add_and_move(folio, op) \ + __folio_batch_add_and_move( \ + &cpu_fbatches.op, \ + folio, \ + op, \ + offsetof(struct cpu_fbatches, op) >= \ + offsetof(struct cpu_fbatches, lock_irq) \ ) static void lru_move_tail(struct lruvec *lruvec, struct folio *folio) @@ -231,10 +231,10 @@ static void lru_move_tail(struct lruvec void folio_rotate_reclaimable(struct folio *folio) { if (folio_test_locked(folio) || folio_test_dirty(folio) || - folio_test_unevictable(folio)) + folio_test_unevictable(folio) || !folio_test_lru(folio)) return; - folio_batch_add_and_move(folio, lru_move_tail, true); + folio_batch_add_and_move(folio, lru_move_tail); } void lru_note_cost_unlock_irq(struct lruvec *lruvec, bool file, @@ -328,10 +328,11 @@ static void folio_activate_drain(int cpu void folio_activate(struct folio *folio) { - if (folio_test_active(folio) || folio_test_unevictable(folio)) + if (folio_test_active(folio) || folio_test_unevictable(folio) || + !folio_test_lru(folio)) return; - folio_batch_add_and_move(folio, lru_activate, true); + folio_batch_add_and_move(folio, lru_activate); } #else @@ -507,7 +508,7 @@ void folio_add_lru(struct folio *folio) lru_gen_in_fault() && !(current->flags & PF_MEMALLOC)) folio_set_active(folio); - folio_batch_add_and_move(folio, lru_add, false); + folio_batch_add_and_move(folio, lru_add); } EXPORT_SYMBOL(folio_add_lru); @@ -685,13 +686,13 @@ void lru_add_drain_cpu(int cpu) void deactivate_file_folio(struct folio *folio) { /* Deactivating an unevictable folio will not accelerate reclaim */ - if (folio_test_unevictable(folio)) + if (folio_test_unevictable(folio) || !folio_test_lru(folio)) return; if (lru_gen_enabled() && lru_gen_clear_refs(folio)) return; - folio_batch_add_and_move(folio, lru_deactivate_file, true); + folio_batch_add_and_move(folio, lru_deactivate_file); } /* @@ -704,13 +705,13 @@ void deactivate_file_folio(struct folio */ void folio_deactivate(struct folio *folio) { - if (folio_test_unevictable(folio)) + if (folio_test_unevictable(folio) || !folio_test_lru(folio)) return; if (lru_gen_enabled() ? lru_gen_clear_refs(folio) : !folio_test_active(folio)) return; - folio_batch_add_and_move(folio, lru_deactivate, true); + folio_batch_add_and_move(folio, lru_deactivate); } /** @@ -723,10 +724,11 @@ void folio_deactivate(struct folio *foli void folio_mark_lazyfree(struct folio *folio) { if (!folio_test_anon(folio) || !folio_test_swapbacked(folio) || + !folio_test_lru(folio) || folio_test_swapcache(folio) || folio_test_unevictable(folio)) return; - folio_batch_add_and_move(folio, lru_lazyfree, true); + folio_batch_add_and_move(folio, lru_lazyfree); } void lru_add_drain(void) _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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+ mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm/gup: local lru_add_drain() to avoid lru_add_drain_all() has been added to the -mm mm-new branch. Its filename is mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm/gup: local lru_add_drain() to avoid lru_add_drain_all() Date: Sun, 31 Aug 2025 02:08:26 -0700 (PDT) In many cases, if collect_longterm_unpinnable_folios() does need to drain the LRU cache to release a reference, the cache in question is on this same CPU, and much more efficiently drained by a preliminary local lru_add_drain(), than the later cross-CPU lru_add_drain_all(). Marked for stable, to counter the increase in lru_add_drain_all()s from "mm/gup: check ref_count instead of lru before migration". Note for clean backports: can take 6.16 commit a03db236aebf ("gup: optimize longterm pin_user_pages() for large folio") first. Link: https://lkml.kernel.org/r/165ccfdb-16b5-ac11-0d66-2984293590c8@google.com Signed-off-by: Hugh Dickins <hughd(a)google.com> Cc: <stable(a)vger.kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: Will Deacon <will(a)kernel.org> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/gup.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/gup.c~mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all +++ a/mm/gup.c @@ -2291,6 +2291,8 @@ static unsigned long collect_longterm_un struct folio *folio; long i = 0; + lru_add_drain(); + for (folio = pofs_get_folio(pofs, i); folio; folio = pofs_next_folio(folio, pofs, &i)) { _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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+ mm-gup-check-ref_count-instead-of-lru-before-migration.patch added to mm-new branch

by Andrew Morton

The patch titled Subject: mm/gup: check ref_count instead of lru before migration has been added to the -mm mm-new branch. Its filename is mm-gup-check-ref_count-instead-of-lru-before-migration.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm/gup: check ref_count instead of lru before migration Date: Sun, 31 Aug 2025 02:05:56 -0700 (PDT) Will Deacon reports:- When taking a longterm GUP pin via pin_user_pages(), __gup_longterm_locked() tries to migrate target folios that should not be longterm pinned, for example because they reside in a CMA region or movable zone. This is done by first pinning all of the target folios anyway, collecting all of the longterm-unpinnable target folios into a list, dropping the pins that were just taken and finally handing the list off to migrate_pages() for the actual migration. It is critically important that no unexpected references are held on the folios being migrated, otherwise the migration will fail and pin_user_pages() will return -ENOMEM to its caller. Unfortunately, it is relatively easy to observe migration failures when running pKVM (which uses pin_user_pages() on crosvm's virtual address space to resolve stage-2 page faults from the guest) on a 6.15-based Pixel 6 device and this results in the VM terminating prematurely. In the failure case, 'crosvm' has called mlock(MLOCK_ONFAULT) on its mapping of guest memory prior to the pinning. Subsequently, when pin_user_pages() walks the page-table, the relevant 'pte' is not present and so the faulting logic allocates a new folio, mlocks it with mlock_folio() and maps it in the page-table. Since commit 2fbb0c10d1e8 ("mm/munlock: mlock_page() munlock_page() batch by pagevec"), mlock/munlock operations on a folio (formerly page), are deferred. For example, mlock_folio() takes an additional reference on the target folio before placing it into a per-cpu 'folio_batch' for later processing by mlock_folio_batch(), which drops the refcount once the operation is complete. Processing of the batches is coupled with the LRU batch logic and can be forcefully drained with lru_add_drain_all() but as long as a folio remains unprocessed on the batch, its refcount will be elevated. This deferred batching therefore interacts poorly with the pKVM pinning scenario as we can find ourselves in a situation where the migration code fails to migrate a folio due to the elevated refcount from the pending mlock operation. Hugh Dickins adds:- !folio_test_lru() has never been a very reliable way to tell if an lru_add_drain_all() is worth calling, to remove LRU cache references to make the folio migratable: the LRU flag may be set even while the folio is held with an extra reference in a per-CPU LRU cache. 5.18 commit 2fbb0c10d1e8 may have made it more unreliable. Then 6.11 commit 33dfe9204f29 ("mm/gup: clear the LRU flag of a page before adding to LRU batch") tried to make it reliable, by moving LRU flag clearing; but missed the mlock/munlock batches, so still unreliable as reported. And it turns out to be difficult to extend 33dfe9204f29's LRU flag clearing to the mlock/munlock batches: if they do benefit from batching, mlock/munlock cannot be so effective when easily suppressed while !LRU. Instead, switch to an expected ref_count check, which was more reliable all along: some more false positives (unhelpful drains) than before, and never a guarantee that the folio will prove migratable, but better. Note for stable backports: requires 6.16 commit 86ebd50224c0 ("mm: add folio_expected_ref_count() for reference count calculation") and 6.17 commit ("mm: fix folio_expected_ref_count() when PG_private_2"). Link: https://lkml.kernel.org/r/47c51c9a-140f-1ea1-b692-c4bae5d1fa58@google.com Fixes: 9a4e9f3b2d73 ("mm: update get_user_pages_longterm to migrate pages allocated from CMA region") Signed-off-by: Hugh Dickins <hughd(a)google.com> Reported-by: Will Deacon <will(a)kernel.org> Link: https://lore.kernel.org/linux-mm/20250815101858.24352-1-will@kernel.org/ Cc: <stable(a)vger.kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar(a)kernel.org> Cc: Axel Rasmussen <axelrasmussen(a)google.com> Cc: Chris Li <chrisl(a)kernel.org> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: John Hubbard <jhubbard(a)nvidia.com> Cc: Keir Fraser <keirf(a)google.com> Cc: Konstantin Khlebnikov <koct9i(a)gmail.com> Cc: Li Zhe <lizhe.67(a)bytedance.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Peter Xu <peterx(a)redhat.com> Cc: Shivank Garg <shivankg(a)amd.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: Wei Xu <weixugc(a)google.com> Cc: yangge <yangge1116(a)126.com> Cc: Yuanchu Xie <yuanchu(a)google.com> Cc: Yu Zhao <yuzhao(a)google.com> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/gup.c~mm-gup-check-ref_count-instead-of-lru-before-migration +++ a/mm/gup.c @@ -2307,7 +2307,8 @@ static unsigned long collect_longterm_un continue; } - if (!folio_test_lru(folio) && drain_allow) { + if (drain_allow && folio_ref_count(folio) != + folio_expected_ref_count(folio) + 1) { lru_add_drain_all(); drain_allow = false; } _ Patches currently in -mm which might be from hughd(a)google.com are mm-fix-folio_expected_ref_count-when-pg_private_2.patch mm-gup-check-ref_count-instead-of-lru-before-migration.patch mm-gup-local-lru_add_drain-to-avoid-lru_add_drain_all.patch mm-revert-mm-gup-clear-the-lru-flag-of-a-page-before-adding-to-lru-batch.patch mm-revert-mm-vmscanc-fix-oom-on-swap-stress-test.patch mm-folio_may_be_cached-unless-folio_test_large.patch mm-lru_add_drain_all-do-local-lru_add_drain-first.patch

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+ mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Uladzislau Rezki (Sony)" <urezki(a)gmail.com> Subject: mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc() Date: Sun, 31 Aug 2025 14:10:58 +0200 kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and always allocate memory using the hardcoded GFP_KERNEL flag. This makes them inconsistent with vmalloc(), which was recently extended to support GFP_NOFS and GFP_NOIO allocations. Page table allocations performed during shadow population also ignore the external gfp_mask. To preserve the intended semantics of GFP_NOFS and GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate memalloc scope. This patch: - Extends kasan_populate_vmalloc() and helpers to take gfp_mask; - Passes gfp_mask down to alloc_pages_bulk() and __get_free_page(); - Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore() around apply_to_page_range(); - Updates vmalloc.c and percpu allocator call sites accordingly. Link: https://lkml.kernel.org/r/20250831121058.92971-1-urezki@gmail.com Fixes: 451769ebb7e7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc") Signed-off-by: Uladzislau Rezki (Sony) <urezki(a)gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Cc: Baoquan He <bhe(a)redhat.com> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Alexander Potapenko <glider(a)google.com> Cc: Andrey Konovalov <andreyknvl(a)gmail.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: Vincenzo Frascino <vincenzo.frascino(a)arm.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/kasan.h | 6 +++--- mm/kasan/shadow.c | 31 ++++++++++++++++++++++++------- mm/vmalloc.c | 8 ++++---- 3 files changed, 31 insertions(+), 14 deletions(-) --- a/include/linux/kasan.h~mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc +++ a/include/linux/kasan.h @@ -562,7 +562,7 @@ static inline void kasan_init_hw_tags(vo #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) void kasan_populate_early_vm_area_shadow(void *start, unsigned long size); -int kasan_populate_vmalloc(unsigned long addr, unsigned long size); +int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask); void kasan_release_vmalloc(unsigned long start, unsigned long end, unsigned long free_region_start, unsigned long free_region_end, @@ -574,7 +574,7 @@ static inline void kasan_populate_early_ unsigned long size) { } static inline int kasan_populate_vmalloc(unsigned long start, - unsigned long size) + unsigned long size, gfp_t gfp_mask) { return 0; } @@ -610,7 +610,7 @@ static __always_inline void kasan_poison static inline void kasan_populate_early_vm_area_shadow(void *start, unsigned long size) { } static inline int kasan_populate_vmalloc(unsigned long start, - unsigned long size) + unsigned long size, gfp_t gfp_mask) { return 0; } --- a/mm/kasan/shadow.c~mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc +++ a/mm/kasan/shadow.c @@ -336,13 +336,13 @@ static void ___free_pages_bulk(struct pa } } -static int ___alloc_pages_bulk(struct page **pages, int nr_pages) +static int ___alloc_pages_bulk(struct page **pages, int nr_pages, gfp_t gfp_mask) { unsigned long nr_populated, nr_total = nr_pages; struct page **page_array = pages; while (nr_pages) { - nr_populated = alloc_pages_bulk(GFP_KERNEL, nr_pages, pages); + nr_populated = alloc_pages_bulk(gfp_mask, nr_pages, pages); if (!nr_populated) { ___free_pages_bulk(page_array, nr_total - nr_pages); return -ENOMEM; @@ -354,25 +354,42 @@ static int ___alloc_pages_bulk(struct pa return 0; } -static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) +static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_t gfp_mask) { unsigned long nr_pages, nr_total = PFN_UP(end - start); struct vmalloc_populate_data data; + unsigned int flags; int ret = 0; - data.pages = (struct page **)__get_free_page(GFP_KERNEL | __GFP_ZERO); + data.pages = (struct page **)__get_free_page(gfp_mask | __GFP_ZERO); if (!data.pages) return -ENOMEM; while (nr_total) { nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0])); - ret = ___alloc_pages_bulk(data.pages, nr_pages); + ret = ___alloc_pages_bulk(data.pages, nr_pages, gfp_mask); if (ret) break; data.start = start; + + /* + * page tables allocations ignore external gfp mask, enforce it + * by the scope API + */ + if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO) + flags = memalloc_nofs_save(); + else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) + flags = memalloc_noio_save(); + ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE, kasan_populate_vmalloc_pte, &data); + + if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO) + memalloc_nofs_restore(flags); + else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) + memalloc_noio_restore(flags); + ___free_pages_bulk(data.pages, nr_pages); if (ret) break; @@ -386,7 +403,7 @@ static int __kasan_populate_vmalloc(unsi return ret; } -int kasan_populate_vmalloc(unsigned long addr, unsigned long size) +int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask) { unsigned long shadow_start, shadow_end; int ret; @@ -415,7 +432,7 @@ int kasan_populate_vmalloc(unsigned long shadow_start = PAGE_ALIGN_DOWN(shadow_start); shadow_end = PAGE_ALIGN(shadow_end); - ret = __kasan_populate_vmalloc(shadow_start, shadow_end); + ret = __kasan_populate_vmalloc(shadow_start, shadow_end, gfp_mask); if (ret) return ret; --- a/mm/vmalloc.c~mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc +++ a/mm/vmalloc.c @@ -2026,6 +2026,8 @@ static struct vmap_area *alloc_vmap_area if (unlikely(!vmap_initialized)) return ERR_PTR(-EBUSY); + /* Only reclaim behaviour flags are relevant. */ + gfp_mask = gfp_mask & GFP_RECLAIM_MASK; might_sleep(); /* @@ -2038,8 +2040,6 @@ static struct vmap_area *alloc_vmap_area */ va = node_alloc(size, align, vstart, vend, &addr, &vn_id); if (!va) { - gfp_mask = gfp_mask & GFP_RECLAIM_MASK; - va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node); if (unlikely(!va)) return ERR_PTR(-ENOMEM); @@ -2089,7 +2089,7 @@ retry: BUG_ON(va->va_start < vstart); BUG_ON(va->va_end > vend); - ret = kasan_populate_vmalloc(addr, size); + ret = kasan_populate_vmalloc(addr, size, gfp_mask); if (ret) { free_vmap_area(va); return ERR_PTR(ret); @@ -4826,7 +4826,7 @@ retry: /* populate the kasan shadow space */ for (area = 0; area < nr_vms; area++) { - if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area])) + if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area], GFP_KERNEL)) goto err_free_shadow; } _ Patches currently in -mm which might be from urezki(a)gmail.com are mm-vmalloc-mm-kasan-respect-gfp-mask-in-kasan_populate_vmalloc.patch

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+ ocfs2-fix-recursive-semaphore-deadlock-in-fiemap-call.patch added to mm-hotfixes-unstable branch

by Andrew Morton

The patch titled Subject: ocfs2: fix recursive semaphore deadlock in fiemap call has been added to the -mm mm-hotfixes-unstable branch. Its filename is ocfs2-fix-recursive-semaphore-deadlock-in-fiemap-call.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche… This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Mark Tinguely <mark.tinguely(a)oracle.com> Subject: ocfs2: fix recursive semaphore deadlock in fiemap call Date: Fri, 29 Aug 2025 10:18:15 -0500 syzbot detected a OCFS2 hang due to a recursive semaphore on a FS_IOC_FIEMAP of the extent list on a specially crafted mmap file. context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115 rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185 __down_write_common kernel/locking/rwsem.c:1317 [inline] __down_write kernel/locking/rwsem.c:1326 [inline] down_write+0x1ab/0x1f0 kernel/locking/rwsem.c:1591 ocfs2_page_mkwrite+0x2ff/0xc40 fs/ocfs2/mmap.c:142 do_page_mkwrite+0x14d/0x310 mm/memory.c:3361 wp_page_shared mm/memory.c:3762 [inline] do_wp_page+0x268d/0x5800 mm/memory.c:3981 handle_pte_fault mm/memory.c:6068 [inline] __handle_mm_fault+0x1033/0x5440 mm/memory.c:6195 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1387 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:copy_user_generic arch/x86/include/asm/uaccess_64.h:126 [inline] RIP: 0010:raw_copy_to_user arch/x86/include/asm/uaccess_64.h:147 [inline] RIP: 0010:_inline_copy_to_user include/linux/uaccess.h:197 [inline] RIP: 0010:_copy_to_user+0x85/0xb0 lib/usercopy.c:26 Code: e8 00 bc f7 fc 4d 39 fc 72 3d 4d 39 ec 77 38 e8 91 b9 f7 fc 4c 89 f7 89 de e8 47 25 5b fd 0f 01 cb 4c 89 ff 48 89 d9 4c 89 f6 <f3> a4 0f 1f 00 48 89 cb 0f 01 ca 48 89 d8 5b 41 5c 41 5d 41 5e 41 RSP: 0018:ffffc9000403f950 EFLAGS: 00050256 RAX: ffffffff84c7f101 RBX: 0000000000000038 RCX: 0000000000000038 RDX: 0000000000000000 RSI: ffffc9000403f9e0 RDI: 0000200000000060 RBP: ffffc9000403fa90 R08: ffffc9000403fa17 R09: 1ffff92000807f42 R10: dffffc0000000000 R11: fffff52000807f43 R12: 0000200000000098 R13: 00007ffffffff000 R14: ffffc9000403f9e0 R15: 0000200000000060 copy_to_user include/linux/uaccess.h:225 [inline] fiemap_fill_next_extent+0x1c0/0x390 fs/ioctl.c:145 ocfs2_fiemap+0x888/0xc90 fs/ocfs2/extent_map.c:806 ioctl_fiemap fs/ioctl.c:220 [inline] do_vfs_ioctl+0x1173/0x1430 fs/ioctl.c:532 __do_sys_ioctl fs/ioctl.c:596 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5f13850fd9 RSP: 002b:00007ffe3b3518b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007f5f13850fd9 RDX: 0000200000000040 RSI: 00000000c020660b RDI: 0000000000000004 RBP: 6165627472616568 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3b3518f0 R13: 00007ffe3b351b18 R14: 431bde82d7b634db R15: 00007f5f1389a03b ocfs2_fiemap() takes a read lock of the ip_alloc_sem semaphore (since v2.6.22-527-g7307de80510a) and calls fiemap_fill_next_extent() to read the extent list of this running mmap executable. The user supplied buffer to hold the fiemap information page faults calling ocfs2_page_mkwrite() which will take a write lock (since v2.6.27-38-g00dc417fa3e7) of the same semaphore. This recursive semaphore will hold filesystem locks and causes a hang of the fileystem. The ip_alloc_sem protects the inode extent list and size. Release the read semphore before calling fiemap_fill_next_extent() in ocfs2_fiemap() and ocfs2_fiemap_inline(). This does an unnecessary semaphore lock/unlock on the last extent but simplifies the error path. Link: https://lkml.kernel.org/r/61d1a62b-2631-4f12-81e2-cd689914360b@oracle.com Fixes: 00dc417fa3e7 ("ocfs2: fiemap support") Signed-off-by: Mark Tinguely <mark.tinguely(a)oracle.com> Reported-by: syzbot+541dcc6ee768f77103e7(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=541dcc6ee768f77103e7 Reviewed-by: Joseph Qi <joseph.qi(a)linux.alibaba.com> Cc: Mark Fasheh <mark(a)fasheh.com> Cc: Joel Becker <jlbec(a)evilplan.org> Cc: Junxiao Bi <junxiao.bi(a)oracle.com> Cc: Changwei Ge <gechangwei(a)live.cn> Cc: Jun Piao <piaojun(a)huawei.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/ocfs2/extent_map.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/ocfs2/extent_map.c~ocfs2-fix-recursive-semaphore-deadlock-in-fiemap-call +++ a/fs/ocfs2/extent_map.c @@ -706,6 +706,8 @@ out: * it not only handles the fiemap for inlined files, but also deals * with the fast symlink, cause they have no difference for extent * mapping per se. + * + * Must be called with ip_alloc_sem semaphore held. */ static int ocfs2_fiemap_inline(struct inode *inode, struct buffer_head *di_bh, struct fiemap_extent_info *fieinfo, @@ -717,6 +719,7 @@ static int ocfs2_fiemap_inline(struct in u64 phys; u32 flags = FIEMAP_EXTENT_DATA_INLINE|FIEMAP_EXTENT_LAST; struct ocfs2_inode_info *oi = OCFS2_I(inode); + lockdep_assert_held_read(&oi->ip_alloc_sem); di = (struct ocfs2_dinode *)di_bh->b_data; if (ocfs2_inode_is_fast_symlink(inode)) @@ -732,8 +735,11 @@ static int ocfs2_fiemap_inline(struct in phys += offsetof(struct ocfs2_dinode, id2.i_data.id_data); + /* Release the ip_alloc_sem to prevent deadlock on page fault */ + up_read(&OCFS2_I(inode)->ip_alloc_sem); ret = fiemap_fill_next_extent(fieinfo, 0, phys, id_count, flags); + down_read(&OCFS2_I(inode)->ip_alloc_sem); if (ret < 0) return ret; } @@ -802,9 +808,11 @@ int ocfs2_fiemap(struct inode *inode, st len_bytes = (u64)le16_to_cpu(rec.e_leaf_clusters) << osb->s_clustersize_bits; phys_bytes = le64_to_cpu(rec.e_blkno) << osb->sb->s_blocksize_bits; virt_bytes = (u64)le32_to_cpu(rec.e_cpos) << osb->s_clustersize_bits; - + /* Release the ip_alloc_sem to prevent deadlock on page fault */ + up_read(&OCFS2_I(inode)->ip_alloc_sem); ret = fiemap_fill_next_extent(fieinfo, virt_bytes, phys_bytes, len_bytes, fe_flags); + down_read(&OCFS2_I(inode)->ip_alloc_sem); if (ret) break; _ Patches currently in -mm which might be from mark.tinguely(a)oracle.com are ocfs2-fix-recursive-semaphore-deadlock-in-fiemap-call.patch

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[PATCH v2] uio_hv_generic: Let userspace take care of interrupt mask

by Naman Jain

Remove the logic to set interrupt mask by default in uio_hv_generic driver as the interrupt mask value is supposed to be controlled completely by the user space. If the mask bit gets changed by the driver, concurrently with user mode operating on the ring, the mask bit may be set when it is supposed to be clear, and the user-mode driver will miss an interrupt which will cause a hang. For eg- when the driver sets inbound ring buffer interrupt mask to 1, the host does not interrupt the guest on the UIO VMBus channel. However, setting the mask does not prevent the host from putting a message in the inbound ring buffer. So let’s assume that happens, the host puts a message into the ring buffer but does not interrupt. Subsequently, the user space code in the guest sets the inbound ring buffer interrupt mask to 0, saying “Hey, I’m ready for interrupts”. User space code then calls pread() to wait for an interrupt. Then one of two things happens: * The host never sends another message. So the pread() waits forever. * The host does send another message. But because there’s already a message in the ring buffer, it doesn’t generate an interrupt. This is the correct behavior, because the host should only send an interrupt when the inbound ring buffer transitions from empty to not-empty. Adding an additional message to a ring buffer that is not empty is not supposed to generate an interrupt on the guest. Since the guest is waiting in pread() and not removing messages from the ring buffer, the pread() waits forever. This could be easily reproduced in hv_fcopy_uio_daemon if we delay setting interrupt mask to 0. Similarly if hv_uio_channel_cb() sets the interrupt_mask to 1, there’s a race condition. Once user space empties the inbound ring buffer, but before user space sets interrupt_mask to 0, the host could put another message in the ring buffer but it wouldn’t interrupt. Then the next pread() would hang. Fix these by removing all instances where interrupt_mask is changed, while keeping the one in set_event() unchanged to enable userspace control the interrupt mask by writing 0/1 to /dev/uioX. Fixes: 95096f2fbd10 ("uio-hv-generic: new userspace i/o driver for VMBus") Suggested-by: John Starks <jostarks(a)microsoft.com> Signed-off-by: Naman Jain <namjain(a)linux.microsoft.com> Cc: <stable(a)vger.kernel.org> --- Changes since v1: https://lore.kernel.org/all/20250818064846.271294-1-namjain@linux.microsoft… * Added Fixes and Cc stable tags. --- drivers/uio/uio_hv_generic.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c index f19efad4d6f8..3f8e2e27697f 100644 --- a/drivers/uio/uio_hv_generic.c +++ b/drivers/uio/uio_hv_generic.c @@ -111,7 +111,6 @@ static void hv_uio_channel_cb(void *context) struct hv_device *hv_dev; struct hv_uio_private_data *pdata; - chan->inbound.ring_buffer->interrupt_mask = 1; virt_mb(); /* @@ -183,8 +182,6 @@ hv_uio_new_channel(struct vmbus_channel *new_sc) return; } - /* Disable interrupts on sub channel */ - new_sc->inbound.ring_buffer->interrupt_mask = 1; set_channel_read_mode(new_sc, HV_CALL_ISR); ret = hv_create_ring_sysfs(new_sc, hv_uio_ring_mmap); if (ret) { @@ -227,9 +224,7 @@ hv_uio_open(struct uio_info *info, struct inode *inode) ret = vmbus_connect_ring(dev->channel, hv_uio_channel_cb, dev->channel); - if (ret == 0) - dev->channel->inbound.ring_buffer->interrupt_mask = 1; - else + if (ret) atomic_dec(&pdata->refcnt); return ret; -- 2.34.1

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