From b1454b463c217e5bc553acc44b2389d9257c9708 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 23 Oct 2023 23:38:41 -0700 Subject: mm: mlock: avoid folio_within_range() on KSM pages Since commit dc68badcede4 ("mm: mlock: update mlock_pte_range to handle large folio") I've just occasionally seen VM_WARN_ON_FOLIO(folio_test_ksm) warnings from folio_within_range(), in a splurge after testing with KSM hyperactive. folio_referenced_one()'s use of folio_within_vma() is safe because it checks folio_test_large() first; but allow_mlock_munlock() needs to do the same to avoid those warnings (or check !folio_test_ksm() itself? Or move either check into folio_within_range()? Hard to tell without more examples of its use). Link: https://lkml.kernel.org/r/23852f6a-5bfa-1ffd-30db-30c5560ad426@google.com Fixes: dc68badcede4 ("mm: mlock: update mlock_pte_range to handle large folio") Signed-off-by: Hugh Dickins Reviewed-by: Yin Fengwei Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Stefan Roesch Signed-off-by: Andrew Morton --- mm/mlock.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/mlock.c b/mm/mlock.c index aa44456200e3..086546ac5766 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -346,6 +346,10 @@ static inline bool allow_mlock_munlock(struct folio *folio, if (!(vma->vm_flags & VM_LOCKED)) return true; + /* folio_within_range() cannot take KSM, but any small folio is OK */ + if (!folio_test_large(folio)) + return true; + /* folio not in range [start, end), skip mlock */ if (!folio_within_range(folio, vma, start, end)) return false; -- cgit v1.2.3