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| author | Hugh Dickins <hughd@google.com> | 2023-10-23 23:38:41 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-25 16:47:14 -0700 |
| commit | b1454b463c217e5bc553acc44b2389d9257c9708 (patch) | |
| tree | d6fd21b602184f797eb246bce240a4ad23df0690 | |
| parent | 1cbf0a58847b30507611f92ad69964ef37264d14 (diff) | |
| download | lwn-b1454b463c217e5bc553acc44b2389d9257c9708.tar.gz lwn-b1454b463c217e5bc553acc44b2389d9257c9708.zip | |
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 <hughd@google.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Stefan Roesch <shr@devkernel.io>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/mlock.c | 4 |
1 files changed, 4 insertions, 0 deletions
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; |