Re: [PATCH] io_uring: fix early sqd_list removal sqpoll hangs

On 4/13/21 4:43 AM, Pavel Begunkov wrote:

[ 245.463317] INFO: task iou-sqp-1374:1377 blocked for more than 122 seconds. [ 245.463334] task:iou-sqp-1374 state:D flags:0x00004000 [ 245.463345] Call Trace: [ 245.463352] __schedule+0x36b/0x950 [ 245.463376] schedule+0x68/0xe0 [ 245.463385] __io_uring_cancel+0xfb/0x1a0 [ 245.463407] do_exit+0xc0/0xb40 [ 245.463423] io_sq_thread+0x49b/0x710 [ 245.463445] ret_from_fork+0x22/0x30

It happens when sqpoll forgot to run park_task_work and goes to exit, then exiting user may remove ctx from sqd_list, and so corresponding io_sq_thread() -> io_uring_cancel_sqpoll() won't be executed. Hopefully it just stucks in do_exit() in this case.

Added for 5.12, thanks.