The patch below does not apply to the 6.0-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@xxxxxxxxxxxxxxx>.
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")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 2ba99c5e08812494bc57f319fb562f527d9bacd8 Mon Sep 17 00:00:00 2001
From: Jann Horn <jannh@xxxxxxxxxx>
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@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20221128180252.1684965-2-jannh@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20221125213714.4115729-2-jannh@xxxxxxxxxx
Fixes: ba76149f47d8 ("thp: khugepaged")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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);
