The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

2ba99c5e0881 ("mm/khugepaged: fix GUP-fast interaction by sending IPI") 8d3c106e19e8 ("mm/khugepaged: take the right locks for page table retraction") 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE") 58ac9a8993a1 ("mm/khugepaged: attempt to map file/shmem-backed pte-mapped THPs by pmds") 780a4b6fb865 ("mm/khugepaged: check compound_order() in collapse_pte_mapped_thp()") b26e27015ec9 ("mm: thp: convert to use common struct mm_slot") 685405020b9f ("mm/khugepaged: stop using vma linked list") 7d2c4385c341 ("mm/khugepaged: rename prefix of shared collapse functions") 7d8faaf15545 ("mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse") 507228044236 ("mm/khugepaged: record SCAN_PMD_MAPPED when scan_pmd() finds hugepage") a7f4e6e4c47c ("mm/thp: add flag to enforce sysfs THP in hugepage_vma_check()") 50ad2f24b3b4 ("mm/khugepaged: propagate enum scan_result codes back to callers") 9710a78ab2ae ("mm/khugepaged: dedup and simplify hugepage alloc and charging") 34d6b470ab9c ("mm/khugepaged: add struct collapse_control") c6a7f445a272 ("mm: khugepaged: don't carry huge page to the next loop for !CONFIG_NUMA") 1064026bab9f ("mm: khugepaged: reorg some khugepaged helpers") 7da4e2cb8b1f ("mm: thp: kill __transhuge_page_enabled()") 9fec51689ff6 ("mm: thp: kill transparent_hugepage_active()") f707fa493784 ("mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate") 4fa6893faeaa ("mm: thp: consolidate vma size check to transhuge_vma_suitable")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2ba99c5e08812494bc57f319fb562f527d9bacd8 Mon Sep 17 00:00:00 2001 From: Jann Horn jannh@google.com Date: Fri, 25 Nov 2022 22:37:13 +0100 Subject: [PATCH] mm/khugepaged: fix GUP-fast interaction by sending IPI

Since commit 70cbc3cc78a99 ("mm: gup: fix the fast GUP race against THP collapse"), the lockless_pages_from_mm() fastpath rechecks the pmd_t to ensure that the page table was not removed by khugepaged in between.

However, lockless_pages_from_mm() still requires that the page table is not concurrently freed. Fix it by sending IPIs (if the architecture uses semi-RCU-style page table freeing) before freeing/reusing page tables.

Link: https://lkml.kernel.org/r/20221129154730.2274278-2-jannh@google.com Link: https://lkml.kernel.org/r/20221128180252.1684965-2-jannh@google.com Link: https://lkml.kernel.org/r/20221125213714.4115729-2-jannh@google.com Fixes: ba76149f47d8 ("thp: khugepaged") Signed-off-by: Jann Horn jannh@google.com Reviewed-by: Yang Shi shy828301@gmail.com Acked-by: David Hildenbrand david@redhat.com Cc: John Hubbard jhubbard@nvidia.com Cc: Peter Xu peterx@redhat.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 492dce43236e..cab7cfebf40b 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -222,12 +222,16 @@ extern void tlb_remove_table(struct mmu_gather *tlb, void *table); #define tlb_needs_table_invalidate() (true) #endif

+void tlb_remove_table_sync_one(void); + #else

#ifdef tlb_needs_table_invalidate #error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE #endif

+static inline void tlb_remove_table_sync_one(void) { } + #endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */

diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 0a11e132ad6b..294cb75d9c22 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1051,6 +1051,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, _pmd = pmdp_collapse_flush(vma, address, pmd); spin_unlock(pmd_ptl); mmu_notifier_invalidate_range_end(&range); + tlb_remove_table_sync_one();

spin_lock(pte_ptl); result = __collapse_huge_page_isolate(vma, address, pte, cc, @@ -1410,6 +1411,7 @@ static void collapse_and_free_pmd(struct mm_struct *mm, struct vm_area_struct *v lockdep_assert_held_write(&vma->anon_vma->root->rwsem);

pmd = pmdp_collapse_flush(vma, addr, pmdp); + tlb_remove_table_sync_one(); mm_dec_nr_ptes(mm); page_table_check_pte_clear_range(mm, addr, pmd); pte_free(mm, pmd_pgtable(pmd)); diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c index add4244e5790..3a2c3f8cad2f 100644 --- a/mm/mmu_gather.c +++ b/mm/mmu_gather.c @@ -153,7 +153,7 @@ static void tlb_remove_table_smp_sync(void *arg) /* Simply deliver the interrupt */ }

-static void tlb_remove_table_sync_one(void) +void tlb_remove_table_sync_one(void) { /* * This isn't an RCU grace period and hence the page-tables cannot be @@ -177,8 +177,6 @@ static void tlb_remove_table_free(struct mmu_table_batch *batch)

#else /* !CONFIG_MMU_GATHER_RCU_TABLE_FREE */

-static void tlb_remove_table_sync_one(void) { } - static void tlb_remove_table_free(struct mmu_table_batch *batch) { __tlb_remove_table_free(batch);