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WARNING: CPU: 1 PID: 27907 at fs/io_uring.c:7147 io_sq_thread_park+0xb5/0xd0 fs/io_uring.c:7147
CPU: 1 PID: 27907 Comm: iou-sqp-27905 Not tainted 5.12.0-rc4-syzkaller #0
RIP: 0010:io_sq_thread_park+0xb5/0xd0 fs/io_uring.c:7147
Call Trace:
io_ring_ctx_wait_and_kill+0x214/0x700 fs/io_uring.c:8619
io_uring_release+0x3e/0x50 fs/io_uring.c:8646
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
io_run_task_work fs/io_uring.c:2238 [inline]
io_run_task_work fs/io_uring.c:2228 [inline]
io_uring_try_cancel_requests+0x8ec/0xc60 fs/io_uring.c:8770
io_uring_cancel_sqpoll+0x1cf/0x290 fs/io_uring.c:8974
io_sqpoll_cancel_cb+0x87/0xb0 fs/io_uring.c:8907
io_run_task_work_head+0x58/0xb0 fs/io_uring.c:1961
io_sq_thread+0x3e2/0x18d0 fs/io_uring.c:6763
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
May happen that last ctx ref is killed in io_uring_cancel_sqpoll(), so
fput callback (i.e. io_uring_release()) is enqueued through task_work,
and run by same cancellation. As it's deeply nested we can't do parking
or taking sqd->lock there, because its state is unclear. So avoid
ctx ejection from sqd list from io_ring_ctx_wait_and_kill() and do it
in a clear context in io_ring_exit_work().
Fixes: f6d54255f4 ("io_uring: halt SQO submission on ctx exit")
Reported-by: syzbot+e3a3f84f5cecf61f0583@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e90df88b8ff2cabb14a7534601d35d62ab4cb8c7.1616496707.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.