https://github.com/torvalds/linux
Revision f0e20b8943509d81200cef5e30af2adfddba0f5c authored by Pavel Begunkov on 06 March 2020, 22:15:22 UTC, committed by Jens Axboe on 07 March 2020, 15:35:56 UTC
There is a recipe to deadlock the kernel: submit a timeout sqe with a
linked_timeout (e.g.  test_single_link_timeout_ception() from liburing),
and SIGKILL the process.

Then, io_kill_timeouts() takes @ctx->completion_lock, but the timeout
isn't flagged with REQ_F_COMP_LOCKED, and will try to double grab it
during io_put_free() to cancel the linked timeout. Probably, the same
can happen with another io_kill_timeout() call site, that is
io_commit_cqring().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 parent c1e2148
History
Tip revision: f0e20b8943509d81200cef5e30af2adfddba0f5c authored by Pavel Begunkov on 06 March 2020, 22:15:22 UTC
io_uring: fix lockup with timeouts
Tip revision: f0e20b8
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