The patch titled
Subject: mm/mmu_notifier: fix mmget() assert in __mmu_interval_notifier_insert
has been added to the -mm tree. Its filename is
mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert.patch
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------------------------------------------------------
From: Jann Horn <jannh@xxxxxxxxxx>
Subject: 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.
Link: https://lkml.kernel.org/r/20200901000143.207585-1-jannh@xxxxxxxxxx
Fixes: 99cb252f5e68 ("mm/mmu_notifier: add an interval tree notifier")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmu_notifier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mmu_notifier.c~mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert
+++ a/mm/mmu_notifier.c
@@ -913,7 +913,7 @@ static int __mmu_interval_notifier_inser
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() */
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
mm-mmu_notifier-fix-mmget-assert-in-__mmu_interval_notifier_insert.patch
binfmt_elf_fdpic-stop-using-dump_emit-on-user-pointers-on-mmu.patch
coredump-let-dump_emit-bail-out-on-short-writes.patch
coredump-refactor-page-range-dumping-into-common-helper.patch
coredump-rework-elf-elf_fdpic-vma_dump_size-into-common-helper.patch
binfmt_elf-binfmt_elf_fdpic-use-a-vma-list-snapshot.patch
mm-gup-take-mmap_lock-in-get_dump_page.patch
mm-remove-the-now-unnecessary-mmget_still_valid-hack.patch
