syzbot


INFO: task hung in nilfs_segctor_thread (2)

Status: upstream: reported on 2026/01/06 07:57
Reported-by: syzbot+6f213c09daa0f93dfeb8@syzkaller.appspotmail.com
First crash: 91d, last: 9d06h
Similar bugs (13)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in nilfs_segctor_thread (5) nilfs 1 1 282d 282d 0/29 auto-obsoleted due to no activity on 2025/09/27 08:54
linux-4.19 INFO: task hung in nilfs_segctor_thread nilfs2 1 C 41 1148d 1250d 0/1 upstream: reported C repro on 2022/11/05 03:06
linux-5.15 INFO: task hung in nilfs_segctor_thread (4) origin:upstream 1 C 1 9d03h 9d03h 0/3 upstream: reported C repro on 2026/03/30 01:14
upstream INFO: task hung in nilfs_segctor_thread (6) nilfs 1 C done 34 1d12h 112d 28/29 upstream: reported C repro on 2025/12/17 00:46
linux-5.15 INFO: task hung in nilfs_segctor_thread (2) 1 2 616d 695d 0/3 auto-obsoleted due to no activity on 2024/11/07 22:53
upstream INFO: task hung in nilfs_segctor_thread (3) nilfs 1 138 602d 627d 0/29 auto-obsoleted due to no activity on 2024/10/22 18:08
upstream INFO: task hung in nilfs_segctor_thread nilfs 1 C error 94 1071d 1245d 22/29 fixed on 2023/06/08 14:41
linux-5.15 INFO: task hung in nilfs_segctor_thread 1 3 1081d 1094d 0/3 auto-obsoleted due to no activity on 2023/08/20 05:29
upstream INFO: task hung in nilfs_segctor_thread (4) nilfs 1 1 521d 521d 0/29 auto-obsoleted due to no activity on 2025/01/31 15:40
linux-4.14 INFO: task hung in nilfs_segctor_thread nilfs2 1 C 1 1146d 1146d 0/1 upstream: reported C repro on 2023/02/16 07:03
upstream INFO: task hung in nilfs_segctor_thread (2) nilfs 1 C inconclusive 98 668d 778d 26/29 fixed on 2024/07/09 19:14
linux-6.1 INFO: task hung in nilfs_segctor_thread 1 40 551d 695d 0/3 auto-obsoleted due to no activity on 2024/12/12 18:46
linux-5.15 INFO: task hung in nilfs_segctor_thread (3) 1 1 490d 490d 0/3 auto-obsoleted due to no activity on 2025/03/13 18:17

Sample crash report:
INFO: task segctord:10228 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:segctord        state:D stack:28720 pid:10228 ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 nilfs_transaction_lock+0x252/0x4c0 fs/nilfs2/segment.c:357
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2560 [inline]
 nilfs_segctor_thread+0x527/0x10d0 fs/nilfs2/segment.c:2645
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: task kworker/u4:14:13209 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:14   state:D stack:23120 pid:13209 ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:5)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 nilfs_transaction_lock+0x252/0x4c0 fs/nilfs2/segment.c:357
 nilfs_construct_dsync_segment+0x15a/0x6f0 fs/nilfs2/segment.c:2349
 do_writepages+0x3ba/0x640 mm/page-writeback.c:2491
 __writeback_single_inode+0x156/0x1160 fs/fs-writeback.c:1622
 writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
 wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
 wb_do_writeback fs/fs-writeback.c:2230 [inline]
 wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: task syz.7.3013:18520 blocked for more than 146 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:28112 pid:18520 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 wb_wait_for_completion+0x16f/0x290 fs/fs-writeback.c:191
 sync_inodes_sb+0x1c5/0xa10 fs/fs-writeback.c:2756
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078c21028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016090 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd078016128 R14: 00007fd078016090 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18523 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:28080 pid:18523 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078c00028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016180 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016180 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd078016218 R14: 00007fd078016180 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18524 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:27856 pid:18524 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078bdf028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016270 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016270 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd078016308 R14: 00007fd078016270 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18525 blocked for more than 148 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:28144 pid:18525 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078bbe028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016360 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016360 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0780163f8 R14: 00007fd078016360 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18527 blocked for more than 149 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:23792 pid:18527 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078b9d028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016450 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016450 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0780164e8 R14: 00007fd078016450 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18529 blocked for more than 149 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:29168 pid:18529 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd078b7c028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016540 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016540 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0780165d8 R14: 00007fd078016540 R15: 00007ffefb807e98
 </TASK>
INFO: task syz.7.3013:18530 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.7.3013      state:D stack:29168 pid:18530 ppid:17563  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0x11d1/0x40e0 kernel/sched/core.c:6562
 schedule+0xb9/0x180 kernel/sched/core.c:6638
 rwsem_down_write_slowpath+0xc2e/0x1110 kernel/locking/rwsem.c:1189
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
 iterate_supers+0x11e/0x1d0 fs/super.c:757
 ksys_sync+0x9d/0x170 fs/sync.c:102
 __ia32_sys_sync+0xa/0x10 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd077d9c819
RSP: 002b:00007fd074bec028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007fd078016630 RCX: 00007fd077d9c819
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fd078016630 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd0780166c8 R14: 00007fd078016630 R15: 00007ffefb807e98
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u4:0/9:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2df30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2e750 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8cb2d5a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2d5a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2d5a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
4 locks held by kworker/u4:3/46:
 #0: ffff888017616938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90000b77d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd39fd0 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:594
 #3: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: ip6gre_exit_batch_net+0xc7/0x4a0 net/ipv6/ip6_gre.c:1674
2 locks held by kworker/0:3/3598:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc9000eb2fd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
1 lock held by dhcpcd/3933:
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x288/0x1af0 net/ipv4/devinet.c:1080
2 locks held by getty/4022:
 #0: ffff88814ce32098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: 
ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x429/0x1390 drivers/tty/n_tty.c:2198
2 locks held by kworker/0:15/7950:
 #0: ffff888017472138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005fd7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
2 locks held by kworker/0:16/7951:
 #0: ffff888017470938
 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005fe7d00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
2 locks held by syz.5.1221/10231:
1 lock held by segctord/10228:
 #0: ffff88805498d2a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_lock+0x252/0x4c0 fs/nilfs2/segment.c:357
1 lock held by syz-executor/11713:
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3492
3 locks held by kworker/u4:14/13209:
 #0: ffff88801ca76138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004307d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffff88805498d2a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_lock+0x252/0x4c0 fs/nilfs2/segment.c:357
3 locks held by kworker/u4:23/14270:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: 
ffffc900036f7d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
2 locks held by syz-executor/15697:
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3492
 #1: ffffffff8cb33278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #1: ffffffff8cb33278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3c0/0x890 kernel/rcu/tree_exp.h:962
1 lock held by kworker/0:2/16759:
 #0: ffff8880b8e3ab18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:538
2 locks held by kworker/0:5/16760:
 #0: 
ffff888017470938
 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90003cd7d00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
2 locks held by kworker/0:6/16856:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: 
ffffc9000471fd00
 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
2 locks held by syz.7.3013/18520:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18523:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18524:
 #0: ffff88805887e0e0
 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18525:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18527:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18529:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
2 locks held by syz.7.3013/18530:
 #0: ffff88805887e0e0 (&type->s_umount_key#96){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
 #1: ffff88802488e7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x1a9/0xa10 fs/fs-writeback.c:2754
1 lock held by syz-executor/18739:
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3492
1 lock held by syz.9.3283/19907:
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8dd46ea8 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3492
1 lock held by syz-executor/20009:
 #0: ffffffff8dd46ea8
 (rtnl_mutex){+.+.}-{3:3}, at: tun_detach drivers/net/tun.c:698 [inline]
 (rtnl_mutex){+.+.}-{3:3}, at: tun_chr_close+0x3d/0x1b0 drivers/net/tun.c:3492
3 locks held by syz.4.3310/20021:
 #0: ffff888079269468 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:526 [inline]
 #0: ffff888079269468 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x20e/0x500 net/bluetooth/hci_core.c:2731
 #1: ffff888079268428 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x45b/0xf40 net/bluetooth/hci_sync.c:5233
 #2: ffffffff8cb33278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #2: ffffffff8cb33278 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2ec/0x890 kernel/rcu/tree_exp.h:962

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xeee/0xf30 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 10231 Comm: syz.5.1221 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 a2 e7 ff fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 a3 f2 50 fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 44 89 f9 80 e1 07 38 c1 7c aa 4c
RSP: 0018:ffffc9000375f058 EFLAGS: 00000002
RAX: 1ffffffff2df0a00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc9000375f250 R08: ffff8880244d0237 R09: 1ffff1100489a046
R10: dffffc0000000000 R11: ffffed100489a047 R12: dffffc0000000000
R13: 00000000000026e7 R14: ffffffff96f854a0 R15: 0000000000000000
FS:  00007f99053bb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f99416c138 CR3: 00000000589b2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:117 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:139 [inline]
 wait_for_lsr drivers/tty/serial/8250/8250_port.c:2101 [inline]
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3372 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3394 [inline]
 serial8250_console_write+0xf74/0x17f0 drivers/tty/serial/8250/8250_port.c:3479
 call_console_driver kernel/printk/printk.c:1977 [inline]
 console_emit_next_record+0x79e/0xba0 kernel/printk/printk.c:2777
 console_flush_all kernel/printk/printk.c:-1 [inline]
 console_unlock+0x223/0x630 kernel/printk/printk.c:2906
 vprintk_emit+0x4b3/0x6a0 kernel/printk/printk.c:2303
 _printk+0xda/0x130 kernel/printk/printk.c:2328
 __nilfs_msg+0x2d8/0x3b0 fs/nilfs2/super.c:78
 nilfs_clean_segments+0x5c1/0xa40 fs/nilfs2/segment.c:2533
 nilfs_ioctl_clean_segments fs/nilfs2/ioctl.c:940 [inline]
 nilfs_ioctl+0x203c/0x21a0 fs/nilfs2/ioctl.c:1304
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f990459c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f99053bb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9904816090 RCX: 00007f990459c819
RDX: 0000200000000640 RSI: 0000000040786e88 RDI: 0000000000000005
RBP: 00007f9904632c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9904816128 R14: 00007f9904816090 R15: 00007fffeb799c88
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/29 21:45 linux-6.1.y 1989cd3d56e2 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in nilfs_segctor_thread
2026/01/06 07:56 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in nilfs_segctor_thread
* Struck through repros no longer work on HEAD.