Thanks. > 在 2019年7月9日，08:41，Jens Axboe <axboe@xxxxxxxxx> 写道： > > On 7/8/19 6:37 PM, JackieLiu wrote: >> >> >>> 在 2019年7月9日，06:31，Jens Axboe <axboe@xxxxxxxxx> 写道： >>> >>> On 7/7/19 11:41 PM, Jackie Liu wrote: >>>> INFO: task syz-executor.5:8634 blocked for more than 143 seconds. >>>> Not tainted 5.2.0-rc5+ #3 >>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. >>>> syz-executor.5 D25632 8634 8224 0x00004004 >>>> Call Trace: >>>> context_switch kernel/sched/core.c:2818 [inline] >>>> __schedule+0x658/0x9e0 kernel/sched/core.c:3445 >>>> schedule+0x131/0x1d0 kernel/sched/core.c:3509 >>>> schedule_timeout+0x9a/0x2b0 kernel/time/timer.c:1783 >>>> do_wait_for_common+0x35e/0x5a0 kernel/sched/completion.c:83 >>>> __wait_for_common kernel/sched/completion.c:104 [inline] >>>> wait_for_common kernel/sched/completion.c:115 [inline] >>>> wait_for_completion+0x47/0x60 kernel/sched/completion.c:136 >>>> kthread_stop+0xb4/0x150 kernel/kthread.c:559 >>>> io_sq_thread_stop fs/io_uring.c:2252 [inline] >>>> io_finish_async fs/io_uring.c:2259 [inline] >>>> io_ring_ctx_free fs/io_uring.c:2770 [inline] >>>> io_ring_ctx_wait_and_kill+0x268/0x880 fs/io_uring.c:2834 >>>> io_uring_release+0x5d/0x70 fs/io_uring.c:2842 >>>> __fput+0x2e4/0x740 fs/file_table.c:280 >>>> ____fput+0x15/0x20 fs/file_table.c:313 >>>> task_work_run+0x17e/0x1b0 kernel/task_work.c:113 >>>> tracehook_notify_resume include/linux/tracehook.h:185 [inline] >>>> exit_to_usermode_loop arch/x86/entry/common.c:168 [inline] >>>> prepare_exit_to_usermode+0x402/0x4f0 arch/x86/entry/common.c:199 >>>> syscall_return_slowpath+0x110/0x440 arch/x86/entry/common.c:279 >>>> do_syscall_64+0x126/0x140 arch/x86/entry/common.c:304 >>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe >>>> RIP: 0033:0x412fb1 >>>> Code: 80 3b 7c 0f 84 c7 02 00 00 c7 85 d0 00 00 00 00 00 00 00 48 8b 05 cf >>>> a6 24 00 49 8b 14 24 41 b9 cb 2a 44 00 48 89 ee 48 89 df <48> 85 c0 4c 0f >>>> 45 c8 45 31 c0 31 c9 e8 0e 5b 00 00 85 c0 41 89 c7 >>>> RSP: 002b:00007ffe7ee6a180 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 >>>> RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000412fb1 >>>> RDX: 0000001b2d920000 RSI: 0000000000000000 RDI: 0000000000000003 >>>> RBP: 0000000000000001 R08: 00000000f3a3e1f8 R09: 00000000f3a3e1fc >>>> R10: 00007ffe7ee6a260 R11: 0000000000000293 R12: 000000000075c9a0 >>>> R13: 000000000075c9a0 R14: 0000000000024c00 R15: 000000000075bf2c >>>> >>>> ============================================= >>>> >>>> There is an wrong logic, when kthread_park running >>>> in front of io_sq_thread. >>>> >>>> CPU#0 CPU#1 >>>> >>>> io_sq_thread_stop: int kthread(void *_create): >>>> >>>> kthread_park() >>>> __kthread_parkme(self); <<< Wrong >>>> kthread_stop() >>>> << wait for self->exited >>>> << clear_bit KTHREAD_SHOULD_PARK >>>> >>>> ret = threadfn(data); >>>> | >>>> |- io_sq_thread >>>> |- kthread_should_park() << false >>>> |- schedule() <<< nobody wake up >>>> >>>> stuck CPU#0 stuck CPU#1 >>>> >>>> So, use a new variable sqo_thread_started to ensure that io_sq_thread >>>> run first, then io_sq_thread_stop. >>> >>> I think this looks fine now, I'll apply it. Thanks! >>> >>> Do you have the test case as well? Would like to add it to the >>> liburing arsenal of regression tests. >> >> Yes, I will. but what's the rules for naming file, they look like sha1 >> or MD5 values. > > It's the git sha of the commit that fixed the problem. But don't worry > about that, call it whatever and I'll fix it up, if need be. > > -- > Jens Axboe
