From: Lokesh Gidra <lokeshgidra@google.com>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
surenb@google.com, kernel-team@android.com, aarcange@redhat.com,
peterx@redhat.com, david@redhat.com, axelrasmussen@google.com,
bgeffon@google.com, jannh@google.com, kaleshsingh@google.com,
ngeoffray@google.com, rppt@kernel.org, hdanton@sina.com,
Lokesh Gidra <lokeshgidra@google.com>,
syzbot+49056626fe41e01f2ba7@syzkaller.appspotmail.com
Subject: [PATCH] userfaultfd: fix deadlock warning when locking src and dst VMAs
Date: Thu, 21 Mar 2024 16:58:18 -0700 [thread overview]
Message-ID: <20240321235818.125118-1-lokeshgidra@google.com> (raw)
Use down_read_nested() to avoid the warning.
Reported-by: syzbot+49056626fe41e01f2ba7@syzkaller.appspotmail.com
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
---
mm/userfaultfd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 712160cd41ec..3c3539c573e7 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1444,7 +1444,8 @@ static int uffd_move_lock(struct mm_struct *mm,
*/
down_read(&(*dst_vmap)->vm_lock->lock);
if (*dst_vmap != *src_vmap)
- down_read(&(*src_vmap)->vm_lock->lock);
+ down_read_nested(&(*src_vmap)->vm_lock->lock,
+ SINGLE_DEPTH_NESTING);
}
mmap_read_unlock(mm);
return err;
--
2.44.0.396.g6e790dbe36-goog
next reply other threads:[~2024-03-21 23:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 23:58 Lokesh Gidra [this message]
2024-03-22 0:47 ` Andrew Morton
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