On 03/09/2020 17:04, Jens Axboe wrote: > On 9/3/20 7:21 AM, Hillf Danton wrote: >> >> The smart syzbot found the following issue: >> >> INFO: task syz-executor047:6853 blocked for more than 143 seconds. >> Not tainted 5.9.0-rc3-next-20200902-syzkaller #0 >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. >> task:syz-executor047 state:D stack:28104 pid: 6853 ppid: 6847 flags:0x00004000 >> Call Trace: >> context_switch kernel/sched/core.c:3777 [inline] >> __schedule+0xea9/0x2230 kernel/sched/core.c:4526 >> schedule+0xd0/0x2a0 kernel/sched/core.c:4601 >> schedule_timeout+0x1d8/0x250 kernel/time/timer.c:1855 >> do_wait_for_common kernel/sched/completion.c:85 [inline] >> __wait_for_common kernel/sched/completion.c:106 [inline] >> wait_for_common kernel/sched/completion.c:117 [inline] >> wait_for_completion+0x163/0x260 kernel/sched/completion.c:138 >> io_sq_thread_stop fs/io_uring.c:6906 [inline] >> io_finish_async fs/io_uring.c:6920 [inline] >> io_sq_offload_create fs/io_uring.c:7595 [inline] >> io_uring_create fs/io_uring.c:8671 [inline] >> io_uring_setup+0x1495/0x29a0 fs/io_uring.c:8744 >> do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> >> because the sqo_thread kthread is created in io_sq_offload_create() without >> being waked up. Then in the error branch of that function we will wait for >> the sqo kthread that never runs. It's fixed by waking it up before waiting. > > Looks good - applied, thanks. BTW, I don't see the patch itself, and it's neither in io_uring, block nor fs mailing lists. Hillf, could you please CC proper lists next time? -- Pavel Begunkov
