| Message ID | 23852f6a-5bfa-1ffd-30db-30c5560ad426@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: mlock: avoid folio_within_range() on KSM pages | expand |
Hi Huge, On 10/24/23 14:38, Hugh Dickins wrote: > Since mm-hotfixes-stable 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). Checking folio_test_large() here looks fine to me now. If KSM could support large folio in the future (Not sure whether this will happen in the future), we could revise. > > Fixes: dc68badcede4 ("mm: mlock: update mlock_pte_range to handle large folio") > Signed-off-by: Hugh Dickins <hughd@google.com> Thanks a lot for catching this issue and fixing it. Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
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;
Since mm-hotfixes-stable 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). Fixes: dc68badcede4 ("mm: mlock: update mlock_pte_range to handle large folio") Signed-off-by: Hugh Dickins <hughd@google.com> --- mm/mlock.c | 4 ++++ 1 file changed, 4 insertions(+)