bisecting fixing commit since 4707d8e5727387e36ea99c74d5ff0ad227700fd0 building syzkaller on e6b89e4e5adde15c0dc0a241e03dc215f2e249b3 testing commit 4707d8e5727387e36ea99c74d5ff0ad227700fd0 with gcc (GCC) 8.4.1 20210217 kernel signature: 2caf3065f5d7c43b5e45c38def957c7c099a053fef3d5c704c06ec78ca61208d run #0: crashed: INFO: task hung in pipe_write run #1: crashed: INFO: task hung in pipe_write run #2: crashed: INFO: task hung in pipe_write run #3: crashed: INFO: task hung in pipe_write run #4: crashed: INFO: task hung in pipe_write run #5: crashed: INFO: task hung in pipe_write run #6: crashed: INFO: task hung in pipe_write run #7: crashed: INFO: task hung in pipe_read run #8: crashed: INFO: task hung in pipe_write run #9: crashed: INFO: task hung in vfs_unlink run #10: crashed: INFO: task hung in pipe_write run #11: crashed: INFO: task hung in vfs_unlink run #12: crashed: INFO: task hung in pipe_write run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK testing current HEAD 2965db2e004cf9c92b87c1f559e9812c0ae878c1 testing commit 2965db2e004cf9c92b87c1f559e9812c0ae878c1 with gcc (GCC) 8.4.1 20210217 kernel signature: 464bb2f811e834c884b99895d602982f88dde1ddddeae18a3565e628ef732646 run #0: crashed: INFO: task hung in pipe_write run #1: crashed: INFO: task hung in pipe_write run #2: crashed: INFO: task hung in vfs_unlink run #3: crashed: INFO: task hung in pipe_write run #4: crashed: INFO: task hung in vfs_unlink run #5: crashed: INFO: task hung in vfs_unlink run #6: crashed: INFO: task hung in pipe_read run #7: crashed: INFO: task hung in pipe_write run #8: crashed: INFO: task hung in pipe_write run #9: OK revisions tested: 2, total time: 43m31.750725164s (build: 25m6.502457167s, test: 17m46.941656605s) the crash still happens on HEAD commit msg: Linux 4.19.188 crash: INFO: task hung in pipe_write team0 (unregistering): Port device team_slave_0 removed bond0 (unregistering): Releasing backup interface bond_slave_1 bond0 (unregistering): Releasing backup interface bond_slave_0 bond0 (unregistering): Released all slaves INFO: task syz-executor.5:19364 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29784 19364 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:19591 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29784 19591 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:19689 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29448 19689 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:19758 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29448 19758 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:19927 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29784 19927 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:20810 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29448 20810 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:21246 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29448 21246 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 INFO: task syz-executor.5:21466 blocked for more than 140 seconds. Not tainted 4.19.188-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D29448 21466 5877 0x00000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3619 __mutex_lock_common kernel/locking/mutex.c:1005 [inline] __mutex_lock+0x4c3/0x1200 kernel/locking/mutex.c:1075 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1090 __pipe_lock fs/pipe.c:83 [inline] pipe_write+0xa6/0xd00 fs/pipe.c:380 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x464319 Code: Bad RIP value. RSP: 002b:00007fbe4baab198 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000464319 RDX: 000000000208e24b RSI: 0000000020000040 RDI: 0000000000000000 RBP: 0000000000526220 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007fbe4baab6bc R14: 00000000ffffffff R15: 0000000000000003 Showing all locks held in the system: 1 lock held by khungtaskd/1085: #0: 000000005593e4af (rcu_read_lock){....}, at: debug_show_all_locks+0x5b/0x27a kernel/locking/lockdep.c:4442 1 lock held by in:imklog/5549: #0: 00000000867897d6 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xa7/0xd0 fs/file.c:767 1 lock held by syz-executor.5/5877: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/17587: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:62 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_lock fs/pipe.c:70 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_wait+0x185/0x1b0 fs/pipe.c:118 1 lock held by syz-executor.5/19364: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/19591: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/19689: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/19758: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/19927: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/20810: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/21246: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/21466: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/21836: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/21963: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 1 lock held by syz-executor.5/23621: #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: __pipe_lock fs/pipe.c:83 [inline] #0: 00000000516f8252 (&pipe->mutex/1){+.+.}, at: pipe_write+0xa6/0xd00 fs/pipe.c:380 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1085 Comm: khungtaskd Not tainted 4.19.188-syzkaller #0 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+0x17c/0x226 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x120 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline] watchdog+0x5c3/0xb40 kernel/hung_task.c:287 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60