syzbot


INFO: task hung in pipe_release (2)

Status: upstream: reported on 2025/06/04 18:15
Reported-by: syzbot+e7195e72b4153b3ec0c9@syzkaller.appspotmail.com
First crash: 91d, last: 23d
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-414 INFO: task hung in pipe_release 1 1 2230d 2230d 0/1 auto-closed as invalid on 2019/11/24 16:38
linux-6.6 INFO: task hung in pipe_release 1 1 78d 78d 0/2 upstream: reported on 2025/06/17 14:36
upstream INFO: task hung in pipe_release (5) fs 1 160 245d 354d 0/29 auto-obsoleted due to no activity on 2025/02/21 02:48
upstream INFO: task hung in pipe_release (2) ext4 1 syz done 3 1827d 1858d 15/29 fixed on 2020/09/25 01:17
android-49 INFO: task hung in pipe_release (2) 1 1 2194d 2194d 0/3 auto-closed as invalid on 2019/12/30 22:08
linux-6.1 INFO: task hung in pipe_release 1 2 313d 371d 0/3 auto-obsoleted due to no activity on 2025/02/03 06:35
upstream INFO: task hung in pipe_release (4) fs 1 C done 51 785d 785d 23/29 fixed on 2023/10/12 12:48
android-49 INFO: task hung in pipe_release 1 2 2423d 2335d 0/3 auto-closed as invalid on 2019/07/14 20:38
upstream INFO: task hung in pipe_release (3) fs 1 4 1388d 1502d 0/29 closed as invalid on 2022/02/07 19:19
upstream INFO: task hung in pipe_release fs 1 2 2320d 2485d 0/29 auto-closed as invalid on 2019/10/25 10:11
linux-4.19 INFO: task hung in pipe_release 1 1 1623d 1623d 0/1 auto-closed as invalid on 2021/07/23 11:59
linux-5.15 INFO: task hung in pipe_release 1 2 320d 382d 0/3 auto-obsoleted due to no activity on 2025/01/27 06:00
linux-5.15 INFO: task hung in pipe_release (2) 1 1 161d 161d 0/3 auto-obsoleted due to no activity on 2025/07/04 20:01
upstream INFO: task hung in pipe_release (6) bcachefs 1 syz done 9 21d 188d 2/29 upstream: reported syz repro on 2025/02/27 19:55
upstream INFO: task can't die in pipe_release (2) fs 1 1 1680d 1676d 0/29 auto-closed as invalid on 2021/03/29 10:10

Sample crash report:
INFO: task syz.3.1087:7633 blocked for more than 143 seconds.
      Not tainted 6.1.147-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.1087      state:D stack:26240 pid:7633  ppid:4276   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
 __pipe_lock fs/pipe.c:103 [inline]
 pipe_release+0x4d/0x330 fs/pipe.c:724
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1ca/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd22758ebe9
RSP: 002b:00007fffcdc0c348 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fd2277b7da0 RCX: 00007fd22758ebe9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007fd2277b7da0 R08: 0000000000004544 R09: 00000006cdc0c63f
R10: 00007fd2277b7cb0 R11: 0000000000000246 R12: 00000000000374ca
R13: 00007fd2277b6090 R14: ffffffffffffffff R15: 00007fffcdc0c460
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2b7b0 (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: ffffffff8cb2bfd0 (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: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2ae20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
2 locks held by getty/4028:
 #0: ffff888030572098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
1 lock held by dhcpcd/4048:
1 lock held by syz.3.1087/7633:
 #0: ffff88807db57068 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:103 [inline]
 #0: ffff88807db57068 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_release+0x4d/0x330 fs/pipe.c:724
1 lock held by syz.3.1087/7634:
 #0: ffff88807db57068 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_file_to_pipe+0x2a/0x330 fs/splice.c:1038

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3f4/0x470 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4048 Comm: dhcpcd Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:__sigqueue_alloc+0x403/0x520 kernel/signal.c:436
Code: e7 e8 21 60 80 00 4d 8b 3c 24 48 89 df 4c 89 fe e8 72 45 30 00 4c 39 fb 0f 87 e1 00 00 00 e8 84 43 30 00 48 8b 3d 5d 03 4f 0e <8b> 74 24 0c e8 64 88 7f 00 48 85 c0 0f 84 bc 00 00 00 49 89 c7 48
RSP: 0018:ffffc900001e0db8 EFLAGS: 00000006
RAX: ffffffff815082f2 RBX: 0000000000000007 RCX: ffff888019b10000
RDX: 0000000000010000 RSI: 0000000000000007 RDI: ffff88814012f280
RBP: dffffc0000000000 R08: dffffc0000000000 R09: fffffbfff1c3e976
R10: fffffbfff1c3e976 R11: 1ffffffff1c3e975 R12: 0000000000000001
R13: ffffffff81507f92 R14: ffff88807e0c8b00 R15: dffffc0000000000
FS:  00007f40facc9740(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559ec5212168 CR3: 0000000026a74000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __send_signal_locked+0x22f/0xde0 kernel/signal.c:1129
 do_send_sig_info kernel/signal.c:1301 [inline]
 group_send_sig_info+0x1f6/0x250 kernel/signal.c:1449
 do_bpf_send_signal+0x7b/0x150 kernel/trace/bpf_trace.c:840
 irq_work_single+0xd1/0x230 kernel/irq_work.c:211
 irq_work_run_list kernel/irq_work.c:242 [inline]
 irq_work_run+0x152/0x2e0 kernel/irq_work.c:251
 __sysvec_irq_work+0xba/0x350 arch/x86/kernel/irq_work.c:22
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x98/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:206
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 9f 47 f7 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc90003a57cb0 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: ffffffff8c5e0b88 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffff5200074af85
R10: fffff5200074af85 R11: 1ffff9200074af84 R12: ffff8880b8f33e01
R13: dffffc0000000000 R14: dffffc0000000000 R15: 0000000000000020
 arch_irq_work_raise+0x82/0xd0 arch/x86/kernel/irq_work.c:31
 irq_work_queue+0x95/0x140 kernel/irq_work.c:114
 bpf_send_signal_common+0x2b2/0x420 kernel/trace/bpf_trace.c:879
 ____bpf_send_signal kernel/trace/bpf_trace.c:888 [inline]
 bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:886
 bpf_prog_7ba5217f62dcd359+0x38/0x3c
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run2+0x1cd/0x3b0 kernel/trace/bpf_trace.c:2324
 __bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18
 trace_sys_enter+0x6b/0x80 include/trace/events/syscalls.h:18
 syscall_trace_enter+0xf0/0x150 kernel/entry/common.c:81
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f40fad0b189
Code: 16 00 00 00 eb de 66 2e 0f 1f 84 00 00 00 00 00 90 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec d0 00 00 00 49 89 d0 48 85 f6 0f 84
RSP: 002b:00007ffc4c5f98c0 EFLAGS: 00000293 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f40facc9740 RCX: 00007f40fad0b189
RDX: 0000559e9d9d45e0 RSI: 00007ffc4c5f99f0 RDI: 0000000000000011
RBP: 00007ffc4c5fa1a0 R08: 0000000000000008 R09: 0000000000000000
R10: 00007ffc4c5fa1a0 R11: 0000000000000293 R12: 0000559e9d9d45e0
R13: 0000559ec522bdf0 R14: 00000000ffffffff R15: 00007ffc4c5f9f50
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/11 22:59 linux-6.1.y 3594f306da12 c06e8995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in pipe_release
2025/06/04 18:14 linux-6.1.y 58485ff1a74f e565f08d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in pipe_release
* Struck through repros no longer work on HEAD.