syzbot


INFO: task hung in loop_control_ioctl

Status: fixed on 2019/01/15 20:25
Reported-by: syzbot+e2fcaf6485d69d5a8ad5@syzkaller.appspotmail.com
Fix commit: 1dded9acf6dc loop: Avoid circular locking dependency between loop_ctl_mutex and bd_mutex
First crash: 1716d, last: 1520d
similar bugs (5):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: task hung in loop_control_ioctl C 23 1140d 1337d 0/1 public: reported C repro on 2019/04/13 00:01
android-49 INFO: task hung in loop_control_ioctl C 59 1108d 1338d 0/3 public: reported C repro on 2019/04/12 00:00
linux-4.14 INFO: task hung in loop_control_ioctl (2) C inconclusive 7 93d 1014d 0/1 upstream: reported C repro on 2020/02/29 17:00
android-44 INFO: task hung in loop_control_ioctl 6 1681d 1805d 0/2 auto-closed as invalid on 2019/02/22 15:22
linux-4.14 INFO: task hung in loop_control_ioctl 1 1171d 1171d 0/1 auto-closed as invalid on 2020/01/24 04:19

Sample crash report:
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
ip6_tunnel: ip6tnl1 xmit: Local address not yet configured!
INFO: task syz-executor2:18112 blocked for more than 140 seconds.
      Not tainted 4.19.0-rc7+ #57
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D21992 18112   5926 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2825 [inline]
 __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
 schedule+0xfe/0x460 kernel/sched/core.c:3517
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
 loop_control_ioctl+0x91/0x530 drivers/block/loop.c:1998
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457519
Code: 87 0a 8b 0d dd 60 09 01 83 f9 01 0f 85 1c 01 00 00 b9 01 00 00 00 88 0d 19 66 09 01 84 c9 0f 84 fd 00 00 00 b9 01 00 00 00 88 <0d> 02 66 09 01 48 8b 05 9b 71 07 01 48 89 04 24 e8 42 2c fc ff 8b
RSP: 002b:00007f1d87e20c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457519
RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000007
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1d87e216d4
R13: 00000000004c0352 R14: 00000000004d04e0 R15: 00000000ffffffff
INFO: task syz-executor2:18163 blocked for more than 140 seconds.
      Not tainted 4.19.0-rc7+ #57
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D26424 18163   5926 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2825 [inline]
 __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
 schedule+0xfe/0x460 kernel/sched/core.c:3517
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575
 __mutex_lock_common kernel/locking/mutex.c:1002 [inline]
 __mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
 loop_control_ioctl+0x91/0x530 drivers/block/loop.c:1998
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457519
Code: 87 0a 8b 0d dd 60 09 01 83 f9 01 0f 85 1c 01 00 00 b9 01 00 00 00 88 0d 19 66 09 01 84 c9 0f 84 fd 00 00 00 b9 01 00 00 00 88 <0d> 02 66 09 01 48 8b 05 9b 71 07 01 48 89 04 24 e8 42 2c fc ff 8b
RSP: 002b:00007f1d87ddec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 0000000000457519
RDX: 0000000000000000 RSI: 0000000000004c82 RDI: 0000000000000004
RBP: 000000000072c0e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1d87ddf6d4
R13: 00000000004c0365 R14: 00000000004d04f8 R15: 00000000ffffffff
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 978 Comm: khungtaskd Not tainted 4.19.0-rc7+ #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline]
 watchdog+0xb3e/0x1050 kernel/hung_task.c:265
 kthread+0x35a/0x420 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57

Crashes (4):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2018/10/11 15:43 upstream 9dcd936c5312 5f818b4b .config log report
ci-upstream-kasan-gce-root 2018/08/13 04:29 upstream d6dd6431591b 7a88b141 .config log report
ci-upstream-kasan-gce-root 2018/03/30 00:15 upstream 0b412605ef5f d47f0ed6 .config log report
ci-upstream-linux-next-kasan-gce-root 2018/10/11 11:05 linux-next 771b65e89c8a 5f818b4b .config log report
* Struck through repros no longer work on HEAD.