On 5/1/21 5:51 AM, Palash Oswal wrote: > On Sat, May 1, 2021 at 2:35 AM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: >> >> On 4/30/21 7:34 PM, Pavel Begunkov wrote: >>> On 4/30/21 4:02 PM, Palash Oswal wrote: >>>> On Fri, Apr 30, 2021 at 8:03 PM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote: >>>>> >>>>> On 4/30/21 3:21 PM, Palash Oswal wrote: >>>>>> On Thursday, March 18, 2021 at 9:40:21 PM UTC+5:30 syzbot wrote: >>>>>>> >>>>>>> Hello, >>>>>>> >>>>>>> syzbot found the following issue on: >>>>>>> >>>>>>> HEAD commit: 0d7588ab riscv: process: Fix no prototype for arch_dup_tas.. >>>>>>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes >>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=12dde5aed00000 >>>>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=81c0b708b31626cc >>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=11bf59db879676f59e52 >>>>>>> userspace arch: riscv64 >>>>>>> CC: [asml.s...@xxxxxxxxx ax...@xxxxxxxxx io-u...@xxxxxxxxxxxxxxx linux-...@xxxxxxxxxxxxxxx] >>>>>>> >>>>>>> Unfortunately, I don't have any reproducer for this issue yet. >>>>> >>>>> There was so many fixes in 5.12 after this revision, including sqpoll >>>>> cancellation related... Can you try something more up-to-date? Like >>>>> released 5.12 or for-next >>>>> >>>> >>>> The reproducer works for 5.12. >>>> >>>> I tested against the HEAD b1ef997bec4d5cf251bfb5e47f7b04afa49bcdfe >>>> commit on for-next tree >>>> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/?h=for-next >>>> and the reproducer fails. >>> >>> Can't reproduce. Does it hang as in the original's report dmesg? >>> Can you paste logs? >> >> and `uname -r` if you could Great, thanks. I'll take a look later > > root@syzkaller:~# echo 30 > /proc/sys/kernel/hung_task_timeout_secs > root@syzkaller:~# uname -a > Linux syzkaller 5.12.0 #112 SMP Sat May 1 10:13:41 IST 2021 x86_64 GNU/Linux > root@syzkaller:~# ./repro > [ 70.412424] repro[365]: segfault at 0 ip 0000556d88201005 sp > 00007ffc7ddf2cd0 error 6 in repro[556d8] > [ 70.417215] Code: cc 8b 75 c0 48 8b 45 e8 41 b9 00 00 00 00 41 89 > d0 b9 11 80 00 00 ba 03 00 00 00 48 > [ 121.593305] INFO: task iou-sqp-365:366 blocked for more than 30 seconds. > [ 121.594448] Not tainted 5.12.0 #112 > [ 121.595072] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > disables this message. > [ 121.596250] task:iou-sqp-365 state:D stack: 0 pid: 366 > ppid: 364 flags:0x00004004 > [ 121.597514] Call Trace: > [ 121.598019] __schedule+0xb1d/0x1130 > [ 121.598774] ? __sched_text_start+0x8/0x8 > [ 121.599580] ? io_wq_worker_sleeping+0x145/0x500 > [ 121.600442] schedule+0x131/0x1c0 > [ 121.600902] io_uring_cancel_sqpoll+0x288/0x350 > [ 121.601571] ? io_sq_thread_unpark+0xd0/0xd0 > [ 121.602410] ? mutex_lock+0xbb/0x130 > [ 121.603027] ? init_wait_entry+0xe0/0xe0 > [ 121.603573] ? wait_for_completion_killable_timeout+0x20/0x20 > [ 121.604454] io_sq_thread+0x174c/0x18c0 > [ 121.605014] ? io_rsrc_put_work+0x380/0x380 > [ 121.605652] ? init_wait_entry+0xe0/0xe0 > [ 121.606428] ? _raw_spin_lock_irq+0xa5/0x180 > [ 121.607262] ? _raw_spin_lock_irqsave+0x190/0x190 > [ 121.608005] ? calculate_sigpending+0x6b/0xa0 > [ 121.608636] ? io_rsrc_put_work+0x380/0x380 > [ 121.609301] ret_from_fork+0x22/0x30 > > > root@syzkaller:~# ps > PID TTY TIME CMD > 294 ttyS0 00:00:00 login > 357 ttyS0 00:00:00 bash > 365 ttyS0 00:00:00 repro > 370 ttyS0 00:00:00 ps > root@syzkaller:~# kill -9 365 > root@syzkaller:~# [ 305.888970] INFO: task iou-sqp-365:366 blocked > for more than 215 seconds. > [ 305.893275] Not tainted 5.12.0 #112 > [ 305.895507] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > disables this message. > [ 305.899685] task:iou-sqp-365 state:D stack: 0 pid: 366 > ppid: 1 flags:0x00004004 > [ 305.904071] Call Trace: > [ 305.905616] __schedule+0xb1d/0x1130 > [ 305.907660] ? __sched_text_start+0x8/0x8 > [ 305.910314] ? io_wq_worker_sleeping+0x145/0x500 > [ 305.913328] schedule+0x131/0x1c0 > [ 305.914562] io_uring_cancel_sqpoll+0x288/0x350 > [ 305.916513] ? io_sq_thread_unpark+0xd0/0xd0 > [ 305.918346] ? mutex_lock+0xbb/0x130 > [ 305.919616] ? init_wait_entry+0xe0/0xe0 > [ 305.920896] ? wait_for_completion_killable_timeout+0x20/0x20 > [ 305.922805] io_sq_thread+0x174c/0x18c0 > [ 305.923876] ? io_rsrc_put_work+0x380/0x380 > [ 305.924748] ? init_wait_entry+0xe0/0xe0 > [ 305.925523] ? _raw_spin_lock_irq+0xa5/0x180 > [ 305.926353] ? _raw_spin_lock_irqsave+0x190/0x190 > [ 305.927436] ? calculate_sigpending+0x6b/0xa0 > [ 305.928266] ? io_rsrc_put_work+0x380/0x380 > [ 305.929104] ret_from_fork+0x22/0x30 > > The trace from my syzkaller instance: > > Syzkaller hit 'INFO: task hung in io_uring_cancel_sqpoll' bug. > > syz-executor198[307]: segfault at 0 ip 00000000004020f3 sp > 00007ffd21853620 error 6 in syz-executor198379463[401000+96000] > Code: 89 d8 8d 34 90 8b 45 04 ba 03 00 00 00 c1 e0 04 03 45 64 39 c6 > 48 0f 42 f0 45 31 c9 e8 96 8a 04 00 8b 75 00 41 89 d8 4c 89 ef <49> 89 > 06 41 b9 00 00 00 10 b9 11 80 00 00 ba 03 00 00 00 c1 e6 06 > INFO: task iou-sqp-307:308 blocked for more than 120 seconds. > Not tainted 5.12.0 #2 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:iou-sqp-307 state:D stack: 0 pid: 308 ppid: 306 flags:0x00004004 > Call Trace: > context_switch kernel/sched/core.c:4322 [inline] > __schedule+0x75f/0xa10 kernel/sched/core.c:5073 > schedule+0xb7/0x110 kernel/sched/core.c:5152 > io_uring_cancel_sqpoll+0x1c6/0x290 fs/io_uring.c:9018 > io_sq_thread+0xf8c/0x1080 fs/io_uring.c:6836 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > -- Pavel Begunkov
