bisecting fixing commit since 3dd0130f2430decf0cb001b452824515436986d2 building syzkaller on 4a77ae0bdc5cd75ebe88ce7c896aae6bbf457a29 testing commit 3dd0130f2430decf0cb001b452824515436986d2 with gcc (GCC) 8.1.0 kernel signature: ce5c1db10c359a890a9563ed68b1d292d5a2906cda5f7898b2a9718c3df96e6b all runs: crashed: INFO: task hung in sync_inodes_sb testing current HEAD 0da0a8a0a0e1845f495431c3d8d733d2bbf9e9e5 testing commit 0da0a8a0a0e1845f495431c3d8d733d2bbf9e9e5 with gcc (GCC) 8.1.0 kernel signature: de891369d38d75d18a58a7db2b99101d300615d11af13597ea2b9d31cc21a065 all runs: crashed: INFO: task hung in sync_inodes_sb revisions tested: 2, total time: 24m16.793904386s (build: 10m16.481707604s, test: 13m22.659562516s) the crash still happens on HEAD commit msg: Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi crash: INFO: task hung in sync_inodes_sb INFO: task syz-executor.2:6152 blocked for more than 143 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.2 state:D stack:11664 pid: 6152 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007ffe39235928 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffe392359d0 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffe39236a60 R13: 00000000033e7a60 R14: 0000000000000000 R15: 00007ffe39236a60 INFO: task syz-executor.4:6154 blocked for more than 143 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.4 state:D stack:11552 pid: 6154 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007fffe374b968 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007fffe374ba10 RBP: 0000000000000006 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007fffe374caa0 R13: 0000000001f6ba60 R14: 0000000000000000 R15: 00007fffe374caa0 INFO: task syz-executor.1:6157 blocked for more than 143 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.1 state:D stack:11624 pid: 6157 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007ffd1759bec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffd1759bf70 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffd1759d000 R13: 00000000016bea60 R14: 0000000000000000 R15: 00007ffd1759d000 INFO: task syz-executor.3:6158 blocked for more than 143 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.3 state:D stack:11472 pid: 6158 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007ffce7c730c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffce7c73170 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffce7c74200 R13: 00000000020b0a60 R14: 0000000000000000 R15: 00007ffce7c74200 INFO: task syz-executor.5:6160 blocked for more than 144 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.5 state:D stack:11640 pid: 6160 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007fffcc599f98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007fffcc59a040 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007fffcc59b0d0 R13: 000000000262fa60 R14: 0000000000000000 R15: 00007fffcc59b0d0 INFO: task syz-executor.0:6161 blocked for more than 144 seconds. Not tainted 5.11.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.0 state:D stack:11752 pid: 6161 ppid: 1 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:4313 [inline] __schedule+0x429/0x9e0 kernel/sched/core.c:5064 schedule+0x38/0xe0 kernel/sched/core.c:5143 wb_wait_for_completion+0x5b/0x90 fs/fs-writeback.c:209 sync_inodes_sb+0xda/0x4a0 fs/fs-writeback.c:2555 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem+0x4f/0x80 fs/sync.c:67 generic_shutdown_super+0x1d/0x100 fs/super.c:448 kill_block_super+0x1c/0x40 fs/super.c:1393 deactivate_locked_super+0x24/0x60 fs/super.c:335 cleanup_mnt+0xb3/0x140 fs/namespace.c:1118 task_work_run+0x68/0xb0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x229/0x250 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x40/0x80 kernel/entry/common.c:302 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x460887 RSP: 002b:00007ffd1517b8f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000460887 RDX: 0000000000403188 RSI: 0000000000000002 RDI: 00007ffd1517b9a0 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000005 R11: 0000000000000246 R12: 00007ffd1517ca30 R13: 0000000002532a60 R14: 0000000000000000 R15: 00007ffd1517ca30 Showing all locks held in the system: 2 locks held by kworker/u4:0/7: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc90000057e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc90000057e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc90000057e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 2 locks held by kworker/u4:1/24: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc900000ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc900000ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc900000ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 2 locks held by kworker/u4:2/140: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc90000433e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc90000433e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc90000433e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 2 locks held by kworker/u4:3/243: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc90000763e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc90000763e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc90000763e70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 1 lock held by khungtaskd/1159: #0: ffffffff84a13020 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x15/0x1a6 kernel/locking/lockdep.c:6255 1 lock held by in:imklog/5802: #0: ffff88810ce41ef0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x45/0x50 fs/file.c:947 2 locks held by syz-executor.2/6152: #0: ffff888117b180e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff88810406f708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff88810406f708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by syz-executor.4/6154: #0: ffff888117f310e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff88810401c708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff88810401c708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by syz-executor.1/6157: #0: ffff888117d1e0e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff888104074708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff888104074708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by syz-executor.3/6158: #0: ffff888117a6c0e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff888103ffb708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff888103ffb708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by syz-executor.5/6160: #0: ffff888117f2e0e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff8881008be708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff8881008be708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by syz-executor.0/6161: #0: ffff888117e210e0 (&type->s_umount_key#65){+.+.}-{3:3}, at: deactivate_super+0x3e/0x50 fs/super.c:365 #1: ffff88810436b708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:344 [inline] #1: ffff88810436b708 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0xc0/0x4a0 fs/fs-writeback.c:2553 2 locks held by kworker/u4:5/7514: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc90001edbe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc90001edbe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc90001edbe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 2 locks held by kworker/u4:7/7651: #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff888100cadd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 #1: ffffc900020ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] #1: ffffc900020ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #1: ffffc900020ebe70 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x207/0x610 kernel/workqueue.c:2246 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1159 Comm: khungtaskd Not tainted 5.11.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0xa3/0xc8 lib/dump_stack.c:120 nmi_cpu_backtrace.cold.8+0x68/0x82 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0xd5/0xf0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline] watchdog+0x5f1/0x6f0 kernel/hung_task.c:294 kthread+0x145/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60