syzbot

INFO: task syz.2.478:7100 blocked for more than 145 seconds.
      Not tainted 6.11.0-syzkaller-11503-gc824deb1a897 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.478       state:D stack:23808 pid:7100  tgid:7100  ppid:6661   flags:0x00000000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5315 [inline]
 __schedule+0x1895/0x4b30 kernel/sched/core.c:6675
 __schedule_loop kernel/sched/core.c:6752 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6767
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6824
 __mutex_lock_common kernel/locking/mutex.c:684 [inline]
 __mutex_lock+0x6a7/0xd70 kernel/locking/mutex.c:752
 pipe_fasync+0x4c/0x1f0 fs/pipe.c:752
 __fput+0x71b/0x880 fs/file_table.c:428
 task_work_run+0x24f/0x310 kernel/task_work.c:228
 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:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4c1057dff9
RSP: 002b:00007ffe87ff9528 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f4c10737a80 RCX: 00007f4c1057dff9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f4c10737a80 R08: 0000000000000006 R09: 00007ffe87ff981f
R10: 00000000003ffbc4 R11: 0000000000000246 R12: 000000000004e65d
R13: 00007ffe87ff9630 R14: 0000000000000032 R15: ffffffffffffffff
 </TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:0/11:
1 lock held by khungtaskd/30:
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e937ee0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6701
2 locks held by getty/4988:
 #0: ffff88814b7c10a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900031332f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by dhcpcd/5047:
1 lock held by syz.2.478/7100:
 #0: ffff88804fbae068 (&pipe->mutex){+.+.}-{3:3}, at: pipe_fasync+0x4c/0x1f0 fs/pipe.c:752
1 lock held by syz.2.478/7107:
 #0: ffff88804fbae068 (&pipe->mutex){+.+.}-{3:3}, at: splice_file_to_pipe+0x2e/0x500 fs/splice.c:1292
2 locks held by syz.0.505/7206:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted 6.11.0-syzkaller-11503-gc824deb1a897 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xff4/0x1040 kernel/hung_task.c:379
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 101 PID: 5047 Comm: dhcpcd Not tainted 6.11.0-syzkaller-11503-gc824deb1a897 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:32 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:87 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:123 [inline]
RIP: 0010:lock_release+0x198/0xa30 kernel/locking/lockdep.c:5839
Code: eb 03 42 80 3c 3b 00 74 08 4c 89 f7 e8 41 2a 8e 00 4c 89 6c 24 50 48 c7 84 24 b0 00 00 00 00 00 00 00 9c 8f 84 24 b0 00 00 00 <42> 80 3c 3b 00 74 08 4c 89 f7 e8 29 29 8e 00 48 8b 9c 24 b0 00 00
RSP: 0018:ffffc90002f2f780 EFLAGS: 00000046
RAX: ffffffff93e2e6d0 RBX: 1ffff920005e5f06 RCX: ffffffff81703d00
RDX: 0000000000000000 RSI: ffffffff8c6100c0 RDI: ffffffff8c610080
RBP: ffffc90002f2f8b0 R08: ffffffff901cf8af R09: 1ffffffff2039f15
R10: dffffc0000000000 R11: fffffbfff2039f16 R12: 1ffff920005e5efc
R13: ffffffff84c242e1 R14: ffffc90002f2f830 R15: dffffc0000000000
FS:  00007f9fa2849740(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000180 CR3: 000000007ba82000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline]
 _raw_spin_unlock_irqrestore+0x79/0x140 kernel/locking/spinlock.c:194
 __debug_check_no_obj_freed lib/debugobjects.c:998 [inline]
 debug_check_no_obj_freed+0x561/0x580 lib/debugobjects.c:1019
 slab_free_hook mm/slub.c:2274 [inline]
 slab_free mm/slub.c:4580 [inline]
 kmem_cache_free+0x11f/0x420 mm/slub.c:4682
 __sigqueue_free kernel/signal.c:451 [inline]
 collect_signal kernel/signal.c:594 [inline]
 __dequeue_signal+0x4ac/0x5c0 kernel/signal.c:616
 dequeue_signal+0x1e0/0x680 kernel/signal.c:637
 get_signal+0x60d/0x1810 kernel/signal.c:2797
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9fa2916ad5
Code: 85 d2 74 0d 0f 10 02 48 8d 54 24 20 0f 11 44 24 20 64 8b 04 25 18 00 00 00 85 c0 75 27 41 b8 08 00 00 00 b8 0f 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 75 48 8b 15 24 73 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007fff4076f040 EFLAGS: 00000246 ORIG_RAX: 000000000000010f
RAX: fffffffffffffdfe RBX: 0000564216c0be20 RCX: 00007f9fa2916ad5
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000564216c211b0
RBP: 00007fff4076f390 R08: 0000000000000008 R09: 0000000000000000
R10: 00007fff4076f390 R11: 0000000000000246 R12: 0000000000000000
R13: 000056420d9ad610 R14: 00000000ffffffff R15: 0000000000000000
 </TASK>