syzbot


INFO: task hung in sys_sync

Status: auto-obsoleted due to no activity on 2026/06/08 03:16
Subsystems: kernfs
Labels: prio:high
[Documentation on labels]
First crash: 103d, last: 103d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
853e22f1-3e4a-4162-81c3-94141542c990 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in sys_sync 2026/05/24 02:54 2026/05/24 02:54 2026/05/24 03:34 c69befb30ac10e158cc9d1557b508ee3f0eca1de

			
		

Sample crash report:
INFO: task syz.7.438:9165 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.438       state:D stack:26736 pid:9165  tgid:9164  ppid:6304   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 __rwbase_read_lock+0xc3/0x180 kernel/locking/rwbase_rt.c:114
 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline]
 __down_read kernel/locking/rwsem.c:1466 [inline]
 down_read+0x132/0x200 kernel/locking/rwsem.c:1539
 __super_lock fs/super.c:60 [inline]
 super_lock+0x2d6/0x3d0 fs/super.c:122
 __iterat[  571.456801][   T37]  __iterate_supers+0x126/0x290 fs/super.c:926
 ksys_sync fs/sync.c:102 [inline]
 __ia32_sys_sync+0xa0/0x120 fs/sync.c:111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd10f79c799
RSP: 002b:00007fd10d9ee028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd10fa15fa0 RCX: 00007fd10f79c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd10fa15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd10fa16038 R14: 00007fd10fa15fa0 R15: 00007ffd8e58b968
 </TASK>
INFO: task syz.7.438:9167 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.438       state:D stack:28096 pid:9167  tgid:9164  ppid:6304   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 __rwbase_read_lock+0xc3/0x180 kernel/locking/rwbase_rt.c:114
 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline]
 __down_read kernel/locking/rwsem.c:1466 [inline]
 down_read+0x132/0x200 kernel/locking/rwsem.c:1539
 __super_lock fs/super.c:60 [inline]
 super_lock+0x2d6/0x3d0 fs/super.c:122
 __iterate_supers+0x126/0x290 fs/super.c:926
 ksys_sync fs/sync.c:102 [inline]
 __ia32_sys_sync+0xa0/0x120 fs/sync.c:111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd10f79c799
RSP: 002b:00007fd10d9cd028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd10fa16090 RCX: 00007fd10f79c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd10fa16090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd10fa16128 R14: 00007fd10fa16090 R15: 00007ffd8e58b968
 </TASK>
INFO: task syz.7.438:9169 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.438       state:D stack:29024 pid:9169  tgid:9164  ppid:6304   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 __rwbase_read_lock+0xc3/0x180 kernel/locking/rwbase_rt.c:114
 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline]
 __down_read kernel/locking/rwsem.c:1466 [inline]
 down_read+0x132/0x200 kernel/locking/rwsem.c:1539
 __super_lock fs/super.c:60 [inline]
 super_lock+0x2d6/0x3d0 fs/super.c:122
 __iterate_supers+0x126/0x290 fs/super.c:926
 ksys_sync fs/sync.c:102 [inline]
 __ia32_sys_sync+0xa0/0x120 fs/sync.c:111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd10f79c799
RSP: 002b:00007fd10d9ac028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd10fa16180 RCX: 00007fd10f79c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd10fa16180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd10fa16218 R14: 00007fd10fa16180 R15: 00007ffd8e58b968
 </TASK>
INFO: task syz.7.438:9170 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.438       state:D stack:28096 pid:9170  tgid:9164  ppid:6304   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7286
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked+0x1f8f/0x25c0 kernel/locking/rtmutex.c:1760
 __rwbase_read_lock+0xc3/0x180 kernel/locking/rwbase_rt.c:114
 rwbase_read_lock kernel/locking/rwbase_rt.c:147 [inline]
 __down_read kernel/locking/rwsem.c:1466 [inline]
 down_read+0x132/0x200 kernel/locking/rwsem.c:1539
 __super_lock fs/super.c:60 [inline]
 super_lock+0x2d6/0x3d0 fs/super.c:122
 __iterate_supers+0x126/0x290 fs/super.c:926
 ksys_sync fs/sync.c:102 [inline]
 __ia32_sys_sync+0xa0/0x120 fs/sync.c:111
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd10f79c799
RSP: 002b:00007fd10d589028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd10fa16270 RCX: 00007fd10f79c799
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd10fa16270 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd10fa16308 R14: 00007fd10fa16270 R15: 00007ffd8e58b968
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/12:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc90000117c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc90000117c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffffffff8f159ff8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
4 locks held by pr/legacy/17:
1 lock held by khungtaskd/37:
 #0: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:6/146:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc90003a37c40 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc90003a37c40 ((reaper_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
5 locks held by kworker/u8:9/1168:
6 locks held by kworker/u8:11/1371:
1 lock held by udevd/5165:
 #0: ffff888019c4f238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_dop_revalidate+0x9e/0x5e0 fs/kernfs/dir.c:1185
2 locks held by getty/5555:
 #0: ffff88802905e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
5 locks held by sshd-session/5782:
 #0: ffff88803f93e948 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:310
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:288
 #2: ffff888036972118 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff888036972118 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:402
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: __folio_batch_add_and_move+0x283/0xa90 mm/swap.c:-1
5 locks held by syz-executor/5783:
 #0: ffff8880399c4370 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:592 [inline]
 #0: ffff8880399c4370 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x194/0xa10 mm/mmap.c:1286
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:288
 #2: ffff888044e317d8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff888044e317d8 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:402
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: __folio_batch_add_and_move+0x283/0xa90 mm/swap.c:-1
4 locks held by syz-executor/5797:
3 locks held by kworker/0:6/5894:
 #0: ffff888019c03938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff888019c03938 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc9000515fc40 (deferred_process_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc9000515fc40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffffffff8f159ff8 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104
3 locks held by udevd/6815:
1 lock held by syz.7.438/9165:
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.7.438/9167:
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.7.438/9169:
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
1 lock held by syz.7.438/9170:
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
3 locks held by syz-executor/9826:
1 lock held by syz.1.529/10156:
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
 #0: ffff88803e9ac0d0 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0 fs/super.c:122
5 locks held by syz-executor/10212:
 #0: ffff8880757896c8 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:310
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #1: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:288
 #2: ffff88805ef60c58 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #2: ffff88805ef60c58 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x13d/0x210 mm/pgtable-generic.c:402
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline]
 #3: ffffffff8ddcb840 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
 #4: ffff8880b8933f90 ((lock)#2){+.+.}-{3:3}, at: __folio_batch_add_and_move+0x283/0xa90 mm/swap.c:-1
4 locks held by syz-executor/10285:
2 locks held by syz-executor/10806:
 #0: ffffffff8f6a4dc0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8f6a4dc0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8f6a4dc0 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f159ff8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f159ff8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f159ff8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a1/0x1be0 net/core/rtnetlink.c:4071
7 locks held by syz.0.606/10867:
1 lock held by dhcpcd-run-hook/10874:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 17 Comm: pr/legacy Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400
Code: e8 ce e3 94 fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 8f ff fa fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001679d0 EFLAGS: 00000202
RAX: 1ffffffff332a000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff99950730 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff852f6fb0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff999504a0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88812633f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007effbfe3ffdc CR3: 000000000dbba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:128 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
 wait_for_lsr+0x1aa/0x2f0 drivers/tty/serial/8250/8250_port.c:1961
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3234 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3257 [inline]
 serial8250_console_write+0x120d/0x1b90 drivers/tty/serial/8250/8250_port.c:3342
 console_emit_next_record kernel/printk/printk.c:3163 [inline]
 console_flush_one_record+0x68b/0xb90 kernel/printk/printk.c:3269
 legacy_kthread_func+0x1b6/0x250 kernel/printk/printk.c:3712
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/10 03:14 upstream 1f318b96cc84 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in sys_sync
* Struck through repros no longer work on HEAD.