io_uring: fix io_sq_offload_create error handling
Don't set IO_SQ_THREAD_SHOULD_STOP when io_sq_offload_create() has
failed on io_uring_alloc_task_context() but leave everything to
io_sq_thread_finish(), because currently io_sq_thread_finish()
hangs on trying to park it. That's great it stalls there, because
otherwise the following io_sq_thread_stop() would be skipped on
IO_SQ_THREAD_SHOULD_STOP check and the sqo would race for sqd with
freeing ctx.
A simple error injection gives something like this.
[ 245.463955] INFO: task sqpoll-test-hang:523 blocked for more than 122 seconds.
[ 245.463983] Call Trace:
[ 245.463990] __schedule+0x36b/0x950
[ 245.464005] schedule+0x68/0xe0
[ 245.464013] schedule_timeout+0x209/0x2a0
[ 245.464032] wait_for_completion+0x8b/0xf0
[ 245.464043] io_sq_thread_finish+0x44/0x1a0
[ 245.464049] io_uring_setup+0x9ea/0xc80
[ 245.464058] __x64_sys_io_uring_setup+0x16/0x20
[ 245.464064] do_syscall_64+0x38/0x50
[ 245.464073] entry_SYSCALL_64_after_hwframe+0x44/0xae
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 84eb499..3299807 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7856,10 +7856,9 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx,
ret = PTR_ERR(tsk);
goto err;
}
- ret = io_uring_alloc_task_context(tsk, ctx);
- if (ret)
- set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
+
sqd->thread = tsk;
+ ret = io_uring_alloc_task_context(tsk, ctx);
wake_up_new_task(tsk);
if (ret)
goto err;