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Commit 96333187 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

userfaultfd_copy: 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.

Link: http://lkml.kernel.org/r/1485542673-24387-6-git-send-email-rppt@linux.vnet.ibm.com


Signed-off-by: default avatarMike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: default avatarHillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 27d02568

fs/userfaultfd.c

+2 −0
Original line number Diff line number Diff line
@@ -1607,6 +1607,8 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx, 
		ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src,

				   uffdio_copy.len);

		mmput(ctx->mm);

	} else {

		return -ENOSPC;

	}

	if (unlikely(put_user(ret, &user_uffdio_copy->copy)))

		return -EFAULT;