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Use helper > folio_expected_ref_count() + 1 to compare with folio_ref_count() > instead of using is_refcount_suitable(). > > Fixes: 05c5323b2a34 ("mm: track mapcount of large folios in single value") > Reported-by: syzbot+2b99589e33edbe9475ca@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6828470d.a70a0220.38f255.000c.GAE@google.com > Suggested-by: David Hildenbrand > Acked-by: David Hildenbrand > Signed-off-by: Shivank Garg > --- The patch looks fine. I was just wondering about the implications of this on migration. Earlier we had a refcount race between migration and shmem page fault via filemap_get_entry() taking a reference and not releasing it till we take the folio lock, which was held by the migration path. I would like to *think* that real workloads, when migrating pages, will *not* be faulting on those pages simultaneously, just guessing. But now we have a kernel thread (khugepaged) racing against migration. I may just be over-speculating.