The patch titled
Subject: userfaultfd_zeropage: return -ENOSPC in case mm has gone
has been added to the -mm tree. Its filename is
userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Subject: userfaultfd_zeropage: return -ENOSPC in case mm has gone
In the non-cooperative userfaultfd case, the process exit may race with
outstanding mcopy_atomic called by the uffd monitor. Returning -ENOSPC
instead of -EINVAL when mm is already gone will allow uffd monitor to
distinguish this case from other error conditions.
Unfortunately I overlooked userfaultfd_zeropage when updating
userfaultd_copy().
Link: http://lkml.kernel.org/r/1501136819-21857-1-git-send-email-rppt@xxxxxxxxxxxxxxxxxx
Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone")
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 2 ++
1 file changed, 2 insertions(+)
diff -puN fs/userfaultfd.c~userfaultfd_zeropage-return-enospc-in-case-mm-has-gone fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd_zeropage-return-enospc-in-case-mm-has-gone
+++ a/fs/userfaultfd.c
@@ -1643,6 +1643,8 @@ static int userfaultfd_zeropage(struct u
ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start,
uffdio_zeropage.range.len);
mmput(ctx->mm);
+ } else {
+ return -ENOSPC;
}
if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage)))
return -EFAULT;
_
Patches currently in -mm which might be from rppt@xxxxxxxxxxxxxxxxxx are
userfaultfd-non-cooperative-notify-about-unmap-of-destination-during-mremap.patch
userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
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