syzbot


INFO: task hung in __alloc_workqueue

Status: auto-obsoleted due to no activity on 2025/06/24 18:40
Subsystems: kernel
[Documentation on labels]
First crash: 144d, last: 144d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in __alloc_workqueue (2) btrfs 1 syz error 4 3d10h 7d01h 0/29 upstream: reported syz repro on 2025/08/10 21:55

Sample crash report:
INFO: task syz.7.2239:19394 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:syz.7.2239      state:D
 stack:25424 pid:19394 tgid:19392 ppid:18295  task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1b18/0x50e0 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 schedule_timeout+0xb1/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x360/0x630 kernel/sched/completion.c:148
 kthread_flush_worker+0x244/0x300 kernel/kthread.c:1563
 __alloc_workqueue+0x1478/0x1bc0 kernel/workqueue.c:5763
 alloc_workqueue+0xd8/0x210 kernel/workqueue.c:5786
 btrfs_init_workqueues+0x323/0x740 fs/btrfs/disk-io.c:1998
 open_ctree+0x12fe/0x2ab0 fs/btrfs/disk-io.c:3424
 btrfs_fill_super fs/btrfs/super.c:972 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
 btrfs_get_tree+0x1324/0x19e0 fs/btrfs/super.c:2093
 vfs_get_tree+0x92/0x2b0 fs/super.c:1759
 fc_mount+0x1b/0xb0 fs/namespace.c:1293
 btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
 btrfs_get_tree+0x692/0x19e0 fs/btrfs/super.c:2094
 vfs_get_tree+0x92/0x2b0 fs/super.c:1759
 do_new_mount+0x2cf/0xb70 fs/namespace.c:3878
 do_mount fs/namespace.c:4218 [inline]
 __do_sys_mount fs/namespace.c:4429 [inline]
 __se_sys_mount+0x38c/0x400 fs/namespace.c:4406
 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: 0033:0x7f549af8e90a
RSP: 002b:00007f549bd0ae68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f549bd0aef0 RCX: 00007f549af8e90a
RDX: 00002000000055c0 RSI: 0000200000000380 RDI: 00007f549bd0aeb0
RBP: 00002000000055c0 R08: 00007f549bd0aef0 R09: 0000000000000008
R10: 0000000000000008 R11: 0000000000000246 R12: 0000200000000380
R13: 00007f549bd0aeb0 R14: 00000000000055ae R15: 0000200000000300
 </TASK>
INFO: task syz.3.2242:19398 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.3.2242      state:D stack:23336 pid:19398 tgid:19396 ppid:12585  task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5367 [inline]
 __schedule+0x1b18/0x50e0 kernel/sched/core.c:6748
 __schedule_loop kernel/sched/core.c:6825 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6840
 schedule_timeout+0xb1/0x290 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common kernel/sched/completion.c:127 [inline]
 wait_for_completion+0x360/0x630 kernel/sched/completion.c:148
 kthread_flush_worker+0x244/0x300 kernel/kthread.c:1563
 __alloc_workqueue+0x1478/0x1bc0 kernel/workqueue.c:5763
 alloc_workqueue+0xd8/0x210 kernel/workqueue.c:5786
 btrfs_alloc_ordered_workqueue+0x197/0x260 fs/btrfs/async-thread.c:140
 btrfs_init_workqueues+0x194/0x740 fs/btrfs/disk-io.c:1987
 open_ctree+0x12fe/0x2ab0 fs/btrfs/disk-io.c:3424
 btrfs_fill_super fs/btrfs/super.c:972 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
 btrfs_get_tree+0x1324/0x19e0 fs/btrfs/super.c:2093
 vfs_get_tree+0x92/0x2b0 fs/super.c:1759
 fc_mount+0x1b/0xb0 fs/namespace.c:1293
 btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
 btrfs_get_tree+0x692/0x19e0 fs/btrfs/super.c:2094
 vfs_get_tree+0x92/0x2b0 fs/super.c:1759
 do_new_mount+0x2cf/0xb70 fs/namespace.c:3878
 do_mount fs/namespace.c:4218 [inline]
 __do_sys_mount fs/namespace.c:4429 [inline]
 __se_sys_mount+0x38c/0x400 fs/namespace.c:4406
 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: 0033:0x7f23a018e90a
RSP: 002b:00007f23a1072e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f23a1072ef0 RCX: 00007f23a018e90a
RDX: 0000200000005100 RSI: 0000200000000000 RDI: 00007f23a1072eb0
RBP: 0000200000005100 R08: 00007f23a1072ef0 R09: 0000000000000810
R10: 0000000000000810 R11: 0000000000000246 R12: 0000200000000000
R13: 00007f23a1072eb0 R14: 00000000000050f3 R15: 00002000000001c0
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
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 getty/5586:
 #0: ffff88814dcc20a0 (&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
2 locks held by kworker/u8:14/6614:
 #0: ffff88801ac81148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline]
 #0: ffff88801ac81148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319
 #1: ffff8880b8623b08 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x41f/0x7a0 kernel/sched/psi.c:987
1 lock held by syz.7.2239/19394:
 #0: ffff8880486f00e0 (&type->s_umount_key#74/1){+.+.}-{4:4}, at: alloc_super+0x221/0x9d0 fs/super.c:344
1 lock held by syz.3.2242/19398:
 #0: ffff888057cfa0e0 (&type->s_umount_key#74/1){+.+.}-{4:4}, at: alloc_super+0x221/0x9d0 fs/super.c:344
1 lock held by syz-executor/19734:
2 locks held by syz.8.2502/22275:
 #0: ffffffff8f26a528 (bio_slab_lock){+.+.}-{4:4}, at: bio_put_slab block/bio.c:140 [inline]
 #0: ffffffff8f26a528 (bio_slab_lock){+.+.}-{4:4}, at: bioset_exit+0x432/0x650 block/bio.c:1662
 #1: ffffffff8eb3fb40 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x530 kernel/rcu/tree.c:3774
2 locks held by syz.1.2510/22398:
 #0: ffffffff903ee558 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff903ee558 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff903ee558 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x22/0x250 net/core/rtnetlink.c:564
 #1: ffffffff8eb3fb40 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x530 kernel/rcu/tree.c:3774

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

NMI backtrace for cpu 0
CPU: 0 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+0x7ab/0x920 kernel/kthread.c:464
 ret_from_fork+0x4d/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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5833 Comm: syz-executor 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:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x24/0x90 kernel/kcov.c:314
Code: 90 90 90 90 90 90 f3 0f 1e fa 4c 8b 04 24 65 48 8b 14 25 08 c0 3f 93 65 8b 05 08 59 7c 11 25 00 01 ff 00 74 10 3d 00 01 00 00 <75> 5b 83 ba 3c 16 00 00 00 74 52 8b 82 18 16 00 00 83 f8 03 75 47
RSP: 0018:ffffc90000a08e50 EFLAGS: 00000006
RAX: 0000000000010000 RBX: 00000000000316a4 RCX: ffff888034319e00
RDX: ffff888034319e00 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880b8727710 R08: ffffffff81b13d0f R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff8880b87276c0 R14: dffffc0000000000 R15: ffff8880b8727828
FS:  0000555577607500(0000) GS:ffff888125324000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff1c2c0ff8 CR3: 000000004a98e000 CR4: 0000000000350ef0
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 ktime_get_update_offsets_now+0x3f/0x3b0 kernel/time/timekeeping.c:2393
 hrtimer_update_base kernel/time/hrtimer.c:652 [inline]
 hrtimer_interrupt+0x131/0xa40 kernel/time/hrtimer.c:1909
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x112/0x420 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2061 [inline]
RIP: 0010:vprintk_emit+0x702/0xa10 kernel/printk/printk.c:2431
Code: 00 e8 32 5d 21 00 4c 8d bc 24 a0 00 00 00 4d 85 e4 75 07 e8 20 5d 21 00 eb 06 e8 19 5d 21 00 fb 49 bc 00 00 00 00 00 fc ff df <48> c7 c7 00 63 a1 8e 31 f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00
RSP: 0018:ffffc90003bd7980 EFLAGS: 00000293
RAX: ffffffff81a205b7 RBX: 0000000000000000 RCX: ffff888034319e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003bd7a90 R08: ffffffff81a20590 R09: 1ffffffff2079fae
R10: dffffc0000000000 R11: fffffbfff2079faf R12: dffffc0000000000
R13: 1ffff9200077af34 R14: ffffffff81a203f2 R15: ffffc90003bd7a20
 _printk+0xd5/0x120 kernel/printk/printk.c:2457
 __xfs_printk fs/xfs/xfs_message.c:24 [inline]
 xfs_printk_level+0x1cc/0x320 fs/xfs/xfs_message.c:44
 xfs_fs_put_super+0x55/0x150 fs/xfs/xfs_super.c:1173
 generic_shutdown_super+0x13b/0x2d0 fs/super.c:642
 kill_block_super+0x44/0x90 fs/super.c:1710
 xfs_kill_sb+0x15/0x50 fs/xfs/xfs_super.c:2115
 deactivate_locked_super+0xc6/0x130 fs/super.c:473
 cleanup_mnt+0x422/0x4c0 fs/namespace.c:1435
 task_work_run+0x253/0x310 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f015f98e497
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffff1b2f358 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f015fa0e08c RCX: 00007f015f98e497
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffff1b2f410
RBP: 00007ffff1b2f410 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffff1b304a0
R13: 00007f015fa0e08c R14: 0000000000106787 R15: 00007ffff1b304e0
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/26 18:38 upstream 2df0c02dab82 89d30d73 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root INFO: task hung in __alloc_workqueue
* Struck through repros no longer work on HEAD.