INFO: task syz-executor5:4829 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor5 D17480 4829 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fff3ead41f8 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007fff3ead4210 RSI: 00007fff3ead42a0 RDI: 00007fff3ead42a0 RBP: 00000000000002a3 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000202 R12: 00007fff3ead5300 R13: 0000000000dc1940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor6:4831 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor6 D21248 4831 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffcd75a8388 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007ffcd75a83a0 RSI: 00007ffcd75a8430 RDI: 00007ffcd75a8430 RBP: 00000000000002d0 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000206 R12: 00007ffcd75a9490 R13: 0000000000fbd940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor2:4832 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D16904 4832 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffd0a234228 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007ffd0a234240 RSI: 00007ffd0a2342d0 RDI: 00007ffd0a2342d0 RBP: 00000000000002a3 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000206 R12: 00007ffd0a235330 R13: 0000000001f6b940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor1:4833 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D17480 4833 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fff7ab2c0c8 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007fff7ab2c0e0 RSI: 00007fff7ab2c170 RDI: 00007fff7ab2c170 RBP: 00000000000002d8 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000202 R12: 00007fff7ab2d1d0 R13: 0000000000eb4940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor3:4834 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D21248 4834 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc047a0cc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007ffc047a0ce0 RSI: 00007ffc047a0d70 RDI: 00007ffc047a0d70 RBP: 00000000000002b7 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000202 R12: 00007ffc047a1dd0 R13: 0000000001b27940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor4:4835 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor4 D21248 4835 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 do_unlinkat+0x2b7/0xa30 fs/namei.c:4045 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456de7 Code: 0f 1f 00 b8 58 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 7d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc6a432dd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007ffc6a432df0 RSI: 00007ffc6a432e80 RDI: 00007ffc6a432e80 RBP: 00000000000002f1 R08: 0000000000000000 R09: 0000000000000010 R10: 000000000000000a R11: 0000000000000206 R12: 00007ffc6a433ee0 R13: 0000000002410940 R14: 0000000000000000 R15: badc0ffeebadface INFO: task syz-executor0:11936 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D26632 11936 4830 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_read_failed_common kernel/locking/rwsem-xadd.c:269 [inline] rwsem_down_read_failed+0x362/0x610 kernel/locking/rwsem-xadd.c:286 call_rwsem_down_read_failed+0x18/0x30 arch/x86/lib/rwsem.S:94 __down_read arch/x86/include/asm/rwsem.h:83 [inline] __percpu_down_read+0x16e/0x210 kernel/locking/percpu-rwsem.c:85 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:49 [inline] percpu_down_read include/linux/percpu-rwsem.h:59 [inline] __sb_start_write+0x2d7/0x300 fs/super.c:1387 sb_start_write include/linux/fs.h:1566 [inline] mnt_want_write+0x3f/0xc0 fs/namespace.c:360 filename_create+0x13e/0x5b0 fs/namei.c:3630 user_path_create fs/namei.c:3693 [inline] do_symlinkat+0xfe/0x2d0 fs/namei.c:4147 __do_sys_symlink fs/namei.c:4173 [inline] __se_sys_symlink fs/namei.c:4171 [inline] __x64_sys_symlink+0x59/0x80 fs/namei.c:4171 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x456dc7 Code: 64 8b 5d 00 e9 14 fd ff ff 4c 8b 74 24 30 64 c7 45 00 22 00 00 00 bb 22 00 00 00 e9 fd fc ff ff 0f 1f 00 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 9d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc4aa9e7e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000058 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000456dc7 RDX: 00007ffc4aa9e837 RSI: 00000000004c2a24 RDI: 00007ffc4aa9e820 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000017 R10: 0000000000000075 R11: 0000000000000206 R12: 0000000000000010 R13: 000000000004c06f R14: 000000000000005d R15: badc0ffeebadface Showing all locks held in the system: 1 lock held by khungtaskd/792: #0: 00000000dced5997 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4436 2 locks held by rs:main Q:Reg/4652: #0: 00000000702af43c (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 0000000090b4249e (sb_writers#6){++++}, at: file_start_write include/linux/fs.h:2758 [inline] #1: 0000000090b4249e (sb_writers#6){++++}, at: vfs_write+0x42a/0x560 fs/read_write.c:548 1 lock held by rsyslogd/4654: 2 locks held by getty/4777: #0: 000000007c53794b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000015cefbdf (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4778: #0: 0000000030642f27 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000020600ca2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4779: #0: 000000001e16b217 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000a6c438d9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4780: #0: 00000000c3213138 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000f094c6bc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4781: #0: 000000009966848b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000a88c15ad (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4782: #0: 00000000ef5141f5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000007084ba61 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4783: #0: 00000000d9d5d3f5 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000005513da84 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-executor5/4829: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor6/4831: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor2/4832: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor1/4833: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor3/4834: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor4/4835: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 1 lock held by syz-executor3/8054: #0: 0000000090b4249e (sb_writers#6){++++}, at: file_start_write include/linux/fs.h:2758 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: do_sendfile+0xac0/0xe20 fs/read_write.c:1439 2 locks held by syz-executor7/11923: #0: 0000000072a70d99 (&bdev->bd_fsfreeze_mutex){+.+.}, at: freeze_bdev+0x2d/0x250 fs/block_dev.c:496 #1: 0000000090b4249e (sb_writers#6){++++}, at: percpu_down_write+0xaf/0x540 kernel/locking/percpu-rwsem.c:145 1 lock held by syz-executor0/11936: #0: 0000000090b4249e (sb_writers#6){++++}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000090b4249e (sb_writers#6){++++}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 792 Comm: khungtaskd Not tainted 4.19.0-rc2+ #4 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0xb39/0x1040 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