path: root/mm/mmu_notifier.c
diff options
authorJann Horn <>2020-10-15 20:07:43 -0700
committerLinus Torvalds <>2020-10-16 11:11:17 -0700
commitc9682d10271e1025ebfbb1675c7afffbef5c6856 (patch)
tree6f203c4e411b658fdadeab493e4b51311bfa0d6d /mm/mmu_notifier.c
parent295a17302348bc38704ef0f11ca2ce4ce58db2e9 (diff)
mm/mmu_notifier: fix mmget() assert in __mmu_interval_notifier_insert
The comment talks about having to hold mmget() (which means mm_users), but the actual check is on mm_count (which would be mmgrab()). Given that MMU notifiers are torn down in mmput() -> __mmput() -> exit_mmap() -> mmu_notifier_release(), I believe that the comment is correct and the check should be on mm->mm_users. Fix it up accordingly. Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier") Signed-off-by: Jann Horn <> Signed-off-by: Andrew Morton <> Reviewed-by: Jason Gunthorpe <> Cc: John Hubbard <> Cc: Christoph Hellwig <> Cc: Christian K├Ânig < Link: Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/mmu_notifier.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 4fc918163dd3..5654dd19addc 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -913,7 +913,7 @@ static int __mmu_interval_notifier_insert(
return -EOVERFLOW;
/* Must call with a mmget() held */
- if (WARN_ON(atomic_read(&mm->mm_count) <= 0))
+ if (WARN_ON(atomic_read(&mm->mm_users) <= 0))
return -EINVAL;
/* pairs with mmdrop in mmu_interval_notifier_remove() */