* [PATCH 2/2] io_uring; fix files cancel hangs
[not found] <cover.1612957420.git.asml.silence@gmail.com>
@ 2021-02-10 11:45 ` Pavel Begunkov
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From: Pavel Begunkov @ 2021-02-10 11:45 UTC (permalink / raw)
To: Jens Axboe, io-uring; +Cc: stable, syzbot+695b03d82fa8e4901b06
We park SQPOLL task before going into io_uring_cancel_files(), so the
task won't run task_works including those that might be important for
the cancellation passes. In this case it's io_poll_remove_one(), which
frees requests via io_put_req_deferred().
Unpark it for while waiting, it's ok as we disable submissions
beforehand, so no new will be generated.
INFO: task syz-executor893:8493 blocked for more than 143 seconds.
Call Trace:
context_switch kernel/sched/core.c:4327 [inline]
__schedule+0x90c/0x21a0 kernel/sched/core.c:5078
schedule+0xcf/0x270 kernel/sched/core.c:5157
io_uring_cancel_files fs/io_uring.c:8912 [inline]
io_uring_cancel_task_requests+0xe70/0x11a0 fs/io_uring.c:8979
__io_uring_files_cancel+0x110/0x1b0 fs/io_uring.c:9067
io_uring_files_cancel include/linux/io_uring.h:51 [inline]
do_exit+0x2fe/0x2ae0 kernel/exit.c:780
do_group_exit+0x125/0x310 kernel/exit.c:922
__do_sys_exit_group kernel/exit.c:933 [inline]
__se_sys_exit_group kernel/exit.c:931 [inline]
__x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Cc: stable@vger.kernel.org # 5.5+
Reported-by: syzbot+695b03d82fa8e4901b06@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 6b73e38aa1a9..1e803a9afc8e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9056,11 +9056,16 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
break;
io_uring_try_cancel_requests(ctx, task, files);
+
+ if (ctx->sq_data)
+ io_sq_thread_unpark(ctx->sq_data);
prepare_to_wait(&task->io_uring->wait, &wait,
TASK_UNINTERRUPTIBLE);
if (inflight == io_uring_count_inflight(ctx, task, files))
schedule();
finish_wait(&task->io_uring->wait, &wait);
+ if (ctx->sq_data)
+ io_sq_thread_park(ctx->sq_data);
}
}
--
2.24.0
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2021-02-10 11:45 ` [PATCH 2/2] io_uring; fix files cancel hangs Pavel Begunkov
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