syzbot


INFO: task hung in inode_sleep_on_writeback (3)

Status: auto-obsoleted due to no activity on 2025/06/23 20:40
Subsystems: bcachefs
[Documentation on labels]
First crash: 134d, last: 134d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in inode_sleep_on_writeback exfat 1 8 2398d 2685d 0/29 closed as dup on 2019/02/06 13:32
upstream INFO: task hung in inode_sleep_on_writeback (2) fs 1 1 1368d 1368d 0/29 auto-closed as invalid on 2022/02/05 13:28

Sample crash report:
INFO: task kworker/u8:3:53 blocked for more than 143 seconds.
      Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:3    state:D stack:21232 pid:53    tgid:53    ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: writeback wb_workfn (flush-bcachefs-3)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1ac3/0x5090 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 inode_sleep_on_writeback+0x140/0x1f0 fs/fs-writeback.c:1579
 wb_writeback+0x648/0xb90 fs/fs-writeback.c:2192
 wb_check_start_all fs/fs-writeback.c:2284 [inline]
 wb_do_writeback fs/fs-writeback.c:2310 [inline]
 wb_workfn+0x99b/0x10b0 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319
 worker_thread+0x870/0xd30 kernel/workqueue.c:3400
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
INFO: task syz.8.52:6509 blocked for more than 144 seconds.
      Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.8.52        state:D stack:24472 pid:6509  tgid:6508  ppid:6062   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1ac3/0x5090 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 wb_wait_for_completion+0x166/0x270 fs/fs-writeback.c:216
 sync_inodes_sb+0x28f/0xb50 fs/fs-writeback.c:2821
 iterate_supers+0xc6/0x190 fs/super.c:934
 ksys_sync+0xc2/0x1d0 fs/sync.c:102
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f84cb38d169
RSP: 002b:00007f84cc296038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f84cb5a5fa0 RCX: 00007f84cb38d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f84cb5a5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f84cb5a5fa0 R15: 00007ffe0f0070d8
 </TASK>
INFO: task syz.0.70:6722 blocked for more than 144 seconds.
      Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.70        state:D stack:28488 pid:6722  tgid:6721  ppid:6570   task_flags:0x400040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1ac3/0x5090 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6897
 rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1176
 __down_write_common kernel/locking/rwsem.c:1304 [inline]
 __down_write kernel/locking/rwsem.c:1313 [inline]
 down_write+0x1da/0x220 kernel/locking/rwsem.c:1578
 bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
 sync_inodes_sb+0x270/0xb50 fs/fs-writeback.c:2819
 iterate_supers+0xc6/0x190 fs/super.c:934
 ksys_sync+0xc2/0x1d0 fs/sync.c:102
 __do_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7febe418d169
RSP: 002b:00007febe50ba038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007febe43a5fa0 RCX: 00007febe418d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007febe43a5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007febe43a5fa0 R15: 00007fffdbe15528
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u8:1/13:
 #0: ffff88801baf3948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801baf3948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90000127c60 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000127c60 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff8feb7610 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17c/0xd60 net/core/net_namespace.c:606
 #3: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xde/0x880 net/core/dev.c:12420
1 lock held by khungtaskd/31:
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8eb3a760 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x30/0x180 kernel/locking/lockdep.c:6761
2 locks held by kworker/u8:3/53:
 #0: ffff888141ecc948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff888141ecc948 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc90000bd7c60 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc90000bd7c60 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
2 locks held by getty/5579:
 #0: ffff8880319d90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002fde2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x53d/0x16b0 drivers/tty/n_tty.c:2211
3 locks held by kworker/u8:8/5959:
 #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffffc900048cfc60 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
 #1: ffffc900048cfc60 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319
 #2: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:285
2 locks held by syz.4.26/6099:
 #0: ffff888033496d38 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x310 fs/file.c:1213
 #1: ffff8880335b6420 (sb_writers#19){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3033 [inline]
 #1: ffff8880335b6420 (sb_writers#19){.+.+}-{0:0}, at: vfs_write+0x23f/0xd10 fs/read_write.c:680
2 locks held by syz.4.26/6113:
 #0: ffff888034cc55f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x310 fs/file.c:1213
 #1: ffff8880335b6420 (sb_writers#19){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3033 [inline]
 #1: ffff8880335b6420 (sb_writers#19){.+.+}-{0:0}, at: vfs_write+0x23f/0xd10 fs/read_write.c:680
2 locks held by syz.8.52/6509:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x270/0xb50 fs/fs-writeback.c:2819
2 locks held by syz.0.70/6722:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x270/0xb50 fs/fs-writeback.c:2819
2 locks held by syz.3.71/6761:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:387 [inline]
 #1: ffff8880332687d0 (&bdi->wb_switch_rwsem){+.+.}-{4:4}, at: sync_inodes_sb+0x270/0xb50 fs/fs-writeback.c:2819
1 lock held by syz.4.78/7000:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x19b/0x400 fs/super.c:120
1 lock held by syz.8.230/8912:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
1 lock held by syz.0.244/8979:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
5 locks held by syz-executor/8973:
 #0: ffff88807cdb8d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:481 [inline]
 #0: ffff88807cdb8d80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x203/0x510 net/bluetooth/hci_core.c:2678
 #1: ffff88807cdb8078 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x60f/0x1260 net/bluetooth/hci_sync.c:5185
 #2: ffffffff90029828 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2041 [inline]
 #2: ffffffff90029828 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa6/0x240 net/bluetooth/hci_conn.c:2698
 #3: ffff888046289338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x71/0x690 net/bluetooth/l2cap_core.c:1761
 #4: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:336 [inline]
 #4: ffffffff8eb3fc78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x454/0x830 kernel/rcu/tree_exp.h:998
2 locks held by syz-executor/9025:
 #0: ffff88802873a0e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:56 [inline]
 #0: ffff88802873a0e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock_excl fs/super.c:71 [inline]
 #0: ffff88802873a0e0 (&type->s_umount_key#81){++++}-{4:4}, at: deactivate_super+0xb5/0xf0 fs/super.c:505
 #1: ffff888082f00278 (&c->state_lock){+.+.}-{4:4}, at: __bch2_fs_stop+0xff/0x5b0 fs/bcachefs/super.c:633
1 lock held by syz.5.257/9185:
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff8880335b60e0 (&type->s_umount_key#81){++++}-{4:4}, at: super_lock+0x27c/0x400 fs/super.c:120
1 lock held by syz-executor/9468:
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:335 [inline]
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd6a/0x1f60 net/core/rtnetlink.c:4021
1 lock held by syz-executor/9493:
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: __tun_chr_ioctl+0x43a/0x2370 drivers/net/tun.c:3121
1 lock held by syz.6.283/9524:
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:698 [inline]
 #0: ffffffff8fec3e48 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3b/0x1b0 drivers/net/tun.c:3517
2 locks held by cmp/9575:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x4ab/0x4e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0x1058/0x10a0 kernel/hung_task.c:399
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 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: 9577 Comm: rm Not tainted 6.14.0-syzkaller-01103-g2df0c02dab82 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:211 [inline]
RIP: 0010:unwind_next_frame+0x1a8/0x22f0 arch/x86/kernel/unwind_orc.c:494
Code: 89 fe 49 29 c6 49 c1 ee 08 48 c7 c0 b8 0f 6c 91 48 c7 c1 44 6a 98 91 48 29 c1 48 c1 e9 02 31 d2 80 3d f3 33 e6 0c 00 0f 45 d1 <8d> 42 ff 44 39 f0 0f 86 74 18 00 00 44 89 f0 48 8d 1c 85 b8 0f 6c
RSP: 0018:ffffc9000b797770 EFLAGS: 00000202
RAX: ffffffff916c0fb8 RBX: ffffc9000b797888 RCX: 00000000000b16a3
RDX: 00000000000b16a3 RSI: ffffffff8228aff6 RDI: ffffffff816dcb90
RBP: ffffc9000b797875 R08: 0000000000000001 R09: ffffc9000b797930
R10: ffffc9000b797890 R11: ffffffff81aec3d0 R12: dffffc0000000000
R13: ffffc9000b797840 R14: 00000000000128af R15: ffffffff8228aff5
FS:  00007f88bf584380(0000) GS:ffff88812525a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f88bf5ff19c CR3: 000000003e1ac000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 arch_stack_walk+0x11e/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x11a/0x1d0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:319 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4138 [inline]
 slab_alloc_node mm/slub.c:4187 [inline]
 kmem_cache_alloc_noprof+0x1e1/0x390 mm/slub.c:4194
 getname_flags+0xb6/0x530 fs/namei.c:146
 user_path_at+0x24/0x60 fs/namei.c:3084
 user_statfs fs/statfs.c:103 [inline]
 __do_sys_statfs fs/statfs.c:193 [inline]
 __se_sys_statfs+0xdc/0x220 fs/statfs.c:190
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f88bf6d868a
Code: c8 ff c3 b8 03 01 00 00 0f 05 48 3d 00 f0 ff ff 76 10 48 8b 15 8f a7 0d 00 f7 d8 64 89 02 48 83 c8 ff c3 b8 89 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 10 48 8b 15 6f a7 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fffaa754588 EFLAGS: 00000246 ORIG_RAX: 0000000000000089
RAX: ffffffffffffffda RBX: 00007f88bf5fd4f8 RCX: 00007f88bf6d868a
RDX: ffffffffffffff80 RSI: 00007fffaa754600 RDI: 00007f88bf5f572a
RBP: 00007f88bf5f572a R08: 0000000000000000 R09: 000000000000000d
R10: 00007fffaa7543b0 R11: 0000000000000246 R12: 00007fffaa754600
R13: 00007fffaa754778 R14: 00007fffaa754798 R15: 0000000000000000
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/25 20:38 upstream 2df0c02dab82 875573af .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in inode_sleep_on_writeback
* Struck through repros no longer work on HEAD.