syzbot

INFO: task syz-executor407:5839 blocked for more than 143 seconds.
      Not tainted 6.14.0-rc7-syzkaller-00074-ga7f2e10ecd8f #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor407 state:D stack:27056 pid:5839  tgid:5838  ppid:5834   task_flags:0x400140 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0xf43/0x5890 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6857
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6914
 __mutex_lock_common kernel/locking/mutex.c:662 [inline]
 __mutex_lock+0x6bd/0xb10 kernel/locking/mutex.c:730
 bdev_release+0x15a/0x6d0 block/bdev.c:1086
 blkdev_release+0x15/0x20 block/fops.c:660
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 ptrace_notify+0x10e/0x130 kernel/signal.c:2522
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work kernel/entry/common.c:173 [inline]
 syscall_exit_to_user_mode_prepare+0x126/0x290 kernel/entry/common.c:200
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x11/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8d462c839
RSP: 002b:00007fd8d45e4218 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 00007fd8d46b4328 RCX: 00007fd8d462c839
RDX: 0000000000000000 RSI: 000000000000ab03 RDI: 0000000000000003
RBP: 00007fd8d46b4320 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd8d46b432c
R13: 00007fd8d468135c R14: 64626e2f7665642f R15: 0000400000000000
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #0: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #0: ffffffff8e1bd140 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x7f/0x390 kernel/locking/lockdep.c:6746
2 locks held by getty/5570:
 #0: ffff8880364aa0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900033332f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0xfba/0x1480 drivers/tty/n_tty.c:2211
1 lock held by udevd/5835:
 #0: ffff888025bca4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0x41a/0xe20 block/bdev.c:903
1 lock held by syz-executor407/5839:
 #0: ffff888025bca4c8 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_release+0x15a/0x6d0 block/bdev.c:1086

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.14.0-rc7-syzkaller-00074-ga7f2e10ecd8f #0
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+0x116/0x1f0 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:236 [inline]
 watchdog+0xf62/0x12b0 kernel/hung_task.c:399
 kthread+0x3af/0x750 kernel/kthread.c:464
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148
 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 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:106 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:111