syzbot


INFO: task hung in nbd_ioctl (3)

Status: upstream: reported C repro on 2020/11/13 07:37
Reported-by: syzbot+10533a0420aea96ae38a@syzkaller.appspotmail.com
First crash: 644d, last: 93d

Fix bisection: the fix commit could be any of (bisect log):
  2d2791fce891 Linux 4.14.217
  84bae26850e3 Linux 4.14.284
similar bugs (7):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 INFO: task hung in nbd_ioctl C done 18 967d 1040d 1/1 fixed on 2019/12/28 10:32
linux-4.14 INFO: task hung in nbd_ioctl (2) C done 16 713d 959d 1/1 fixed on 2020/10/21 11:01
upstream INFO: task hung in nbd_ioctl (2) 37 721d 774d 17/23 fixed on 2020/09/25 01:17
upstream INFO: task hung in nbd_ioctl C done 71 1018d 1053d 14/23 fixed on 2019/11/06 12:39
linux-4.19 INFO: task hung in nbd_ioctl C error 74 45d 1042d 0/1 upstream: reported C repro on 2019/10/12 13:11
upstream INFO: task hung in nbd_ioctl (3) C done unreliable 21 11d 690d 0/23 upstream: reported C repro on 2020/09/28 07:17
upstream INFO: task can't die in nbd_ioctl C done 7 179d 683d 0/23 upstream: reported C repro on 2020/10/05 07:20

Sample crash report:
block nbd0: shutting down sockets
INFO: task syz-executor744:8024 blocked for more than 140 seconds.
      Not tainted 4.14.217-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor744 D28216  8024   8023 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2808 [inline]
 __schedule+0x88b/0x1de0 kernel/sched/core.c:3384
 schedule+0x8d/0x1b0 kernel/sched/core.c:3428
 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724
 do_wait_for_common kernel/sched/completion.c:91 [inline]
 __wait_for_common kernel/sched/completion.c:112 [inline]
 wait_for_common+0x272/0x430 kernel/sched/completion.c:123
 flush_workqueue+0x3ce/0x1310 kernel/workqueue.c:2676
 nbd_start_device_ioctl drivers/block/nbd.c:1255 [inline]
 __nbd_ioctl drivers/block/nbd.c:1326 [inline]
 nbd_ioctl+0x49d/0xa80 drivers/block/nbd.c:1366
 __blkdev_driver_ioctl block/ioctl.c:297 [inline]
 blkdev_ioctl+0x540/0x1830 block/ioctl.c:594
 block_ioctl+0xd9/0x120 fs/block_dev.c:1893
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x444f39
RSP: 002b:00007ffdb7374f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000444f39
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00000000006cf018 R08: 00000000004002e0 R09: 00000000004002e0
R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000402100
R13: 0000000000402190 R14: 0000000000000000 R15: 0000000000000000

Showing all locks held in the system:
1 lock held by khungtaskd/1531:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffff86feead7>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548
2 locks held by kworker/u5:0/1675:
 #0:  ("knbd%d-recv"nbd->index){+.+.}, at: [<ffffffff81363810>] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087
 #1:  ((&args->work)){+.+.}, at: [<ffffffff81363846>] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091
1 lock held by in:imklog/7711:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff818d061b>] __fdget_pos+0x1fb/0x2b0 fs/file.c:769

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1531 Comm: khungtaskd Not tainted 4.14.217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
 watchdog+0x5b9/0xb40 kernel/hung_task.c:274
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4626 Comm: systemd-journal Not tainted 4.14.217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880a118a1c0 task.stack: ffff8880a1190000
RIP: 0010:hash_name fs/namei.c:2015 [inline]
RIP: 0010:link_path_walk+0x1ea/0x10a0 fs/namei.c:2101
RSP: 0018:ffff8880a1197ae8 EFLAGS: 00000246
RAX: ffff8880b58162c0 RBX: ffff8880b58162c0 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000000 RDI: dffffc0000000000
RBP: 0000000000000000 R08: ffffffff8b9c2788 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a1197cf8
R13: fefefefefefefeff R14: 0000000000000000 R15: ffff888094eec9e5
FS:  00007f1c166218c0(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1c139f7000 CR3: 00000000a1049000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 path_openat+0x15e/0x2970 fs/namei.c:3568
 do_filp_open+0x179/0x3c0 fs/namei.c:3603
 do_sys_open+0x296/0x410 fs/open.c:1081
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f1c15bb1840
RSP: 002b:00007ffc835fb098 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007ffc835fb3a0 RCX: 00007f1c15bb1840
RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 00005617e738df30
RBP: 000000000000000d R08: 000000000000c0c1 R09: 00000000ffffffff
R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00005617e7381040 R14: 00007ffc835fb360 R15: 00005617e738dd50
Code: fe fe fe 48 89 44 24 10 48 89 c3 eb 1e e8 0f 91 cb ff 4d 31 e6 48 83 c5 08 4c 31 f3 49 c1 c6 0c 49 01 de 48 c1 cb 13 48 8d 1c db <e8> f1 90 cb ff 48 ba 2f 2f 2f 2f 2f 2f 2f 2f 48 b8 80 80 80 80 

Crashes (12):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-linux-4-14 2021/01/24 21:19 linux-4.14.y 2d2791fce891 52e37319 .config log report syz C INFO: task hung in nbd_ioctl
ci2-linux-4-14 2022/01/17 17:42 linux-4.14.y 4ba8e26127c3 731a2d23 .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2022/01/17 16:40 linux-4.14.y 4ba8e26127c3 731a2d23 .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2022/01/14 03:31 linux-4.14.y 4ba8e26127c3 b8d780ab .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/12/07 03:17 linux-4.14.y 66722c42ec91 0230ba3e .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/12/04 14:52 linux-4.14.y 66722c42ec91 a617004c .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/05/15 23:12 linux-4.14.y 7d7d1c0ab3eb 93f844de .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/03/31 16:51 linux-4.14.y bd634aa64163 6a81331a .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/03/29 01:18 linux-4.14.y 670d6552eda8 a8529b82 .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/03/28 21:10 linux-4.14.y 670d6552eda8 a8529b82 .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2021/01/24 18:12 linux-4.14.y 2d2791fce891 52e37319 .config log report info INFO: task hung in nbd_ioctl
ci2-linux-4-14 2020/11/13 07:37 linux-4.14.y 27ce4f2a6817 16fca0c8 .config log report info