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Thu, 21 Mar 2024 16:58:51 -0700 (PDT) Date: Thu, 21 Mar 2024 16:58:18 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.44.0.396.g6e790dbe36-goog Message-ID: <20240321235818.125118-1-lokeshgidra@google.com> Subject: [PATCH] userfaultfd: fix deadlock warning when locking src and dst VMAs From: Lokesh Gidra 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 , syzbot+49056626fe41e01f2ba7@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: BA4C640004 X-Stat-Signature: 3kiawyt6uhnihqwrna599q5e5casreez X-HE-Tag: 1711065532-477940 X-HE-Meta: U2FsdGVkX18/Ssvxx+fe3icW/r2fSc5/8pwWLzXVepd9+g7UlKHqDzDpO/MRWNDhEJL+Noed1TKT4Lkx8l4Evee+RZyRGcw6McKHcRZlcYhH732Ihd40BfgXwEd9rqJEbJ9ZkS3M3e0XQ3dYnhg4Fg0eS0488FeIz4hd8fSON9Ya92tmoscTo8dDwZhHy9ZQ7aiZ8hc+9me5JJ61kZUcUYpnzhKl48Jgx8P2VJ/rqndbMY8bO3a0JY+Xlb983EPr7Y9GNZ+N542bmxR2yj3eceURQZpzQRl0ER/zMOA4wfPmeuVYxKWj7L+3fgIMS5pzGwnv3aM8EjvLWzeyw3YnFvUAVSP8eZQ5Rs25sJmrWIVj1XD4BeWy0kmRYPlk8ime1uNK3s49Kgz7r0qfOfL+YK2Cpbt5/+TILOnE5SMmUn1+T/PQOJJ93k+opLGIk8+9dqO5r8F0+kDfFB5KDl5mJTPHC/TJcFLdp8P+zuLh+FK5dn0He8nl5GyhRNUMnaj3GJ6zw0gWU8tWViBiChH5Lhl5bjns70cIEewCCe7/zyxzVBbHt6ZpNdJNJPU65gGpYmOSp5qXSEfPAXQUuF9jvdmGOu7syejjRZXtnQbmWSh/3RHhkZxLjN0DJUdu8cVzC5E2EfGbjI29cWLEs+qHabaMFh/BNmT/V37P/n0EGUegs1/XPaqUhJ4M/3cN17og5yeorVd5ENNfF322uRS/C4bHbXptf9bqL4/zN0w3hY+63orpkQIiAGqz0uxfTjcRkpxb2sPYnAi2xwbkXtsbpJEVtY+Yl2N9tRvR7jA0nIQUFwb7qBn/xGP8wX+gJh8EcpnmtD15FB2WLvEA3ypixiZ9dbVYlm+15rJwAC6eqMl4pkk5HNnZeDsQr9l1IcZs19WSZzfW2QdZ5XoUtxNYjFi9PRmIbYmCyCiH6OSZZnWyumZTc1VFHeGeKlmU7MoK8YNvb1SvmeV9TMSTNDN LfyDEcss 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000475, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Use down_read_nested() to avoid the warning. Reported-by: syzbot+49056626fe41e01f2ba7@syzkaller.appspotmail.com Signed-off-by: Lokesh Gidra --- 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