From: Mike Rapoport <rppt@linux.vnet.ibm.com>
To: Linux-MM <linux-mm@kvack.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Hillf Danton <hillf.zj@alibaba-inc.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
LKML <linux-kernel@vger.kernel.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: [RFC PATCH 5/5] userfaultfd_copy: return -ENOSPC in case mm has gone
Date: Tue, 24 Jan 2017 15:52:03 +0200 [thread overview]
Message-ID: <1485265923-20256-6-git-send-email-rppt@linux.vnet.ibm.com> (raw)
In-Reply-To: <1485265923-20256-1-git-send-email-rppt@linux.vnet.ibm.com>
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.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
---
fs/userfaultfd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 839ffd5..6587f40 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1603,6 +1603,8 @@ 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;
--
1.9.1
--
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next prev parent reply other threads:[~2017-01-24 13:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 13:51 [RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes Mike Rapoport
2017-01-24 13:51 ` [RFC PATCH 1/5] mm: call vm_munmap in munmap syscall instead of using open coded version Mike Rapoport
2017-01-24 13:52 ` [RFC PATCH 2/5] userfaultfd: non-cooperative: add event for memory unmaps Mike Rapoport
2017-01-24 13:52 ` [RFC PATCH 3/5] userfaultfd: non-cooperative: add event for exit() notification Mike Rapoport
2017-01-24 13:52 ` [RFC PATCH 4/5] userfaultfd: mcopy_atomic: return -ENOENT when no compatible VMA found Mike Rapoport
2017-01-24 13:52 ` Mike Rapoport [this message]
2017-01-26 5:50 ` [RFC PATCH 0/5] userfaultfd: non-cooperative: better tracking for mapping changes Hillf Danton
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