syzbot

INFO: task kworker/0:2:339 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:2     state:D stack:0     pid:339   tgid:339   ppid:2      flags:0x00004000
Workqueue: events p9_write_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7944
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x81e/0x1b50 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x102/0x1c0 kernel/locking/mutex.c:285
 pipe_write+0x134/0x18a0 fs/pipe.c:455
 __kernel_write_iter+0x395/0x830 fs/read_write.c:617
 __kernel_write fs/read_write.c:637 [inline]
 kernel_write+0x2e6/0x6b0 fs/read_write.c:658
 p9_fd_write net/9p/trans_fd.c:433 [inline]
 p9_write_work+0x551/0xd30 net/9p/trans_fd.c:484
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x7d5/0x1020 kernel/workqueue.c:3319
 worker_thread+0xc58/0x1250 kernel/workqueue.c:3400
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 3aa8e93a75ec4fb080c21ea51d8727149e6cfac5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x10c/0x190 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2bf/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xd8f/0xed0 kernel/hung_task.c:423
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x64/0xa0 arch/x86/kernel/process.c:153
 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: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 3aa8e93a75ec4fb080c21ea51d8727149e6cfac5
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:asm_sysvec_call_function_single+0x0/0x30 arch/x86/include/asm/idtentry.h:709
Code: ca fc 6a ff e8 e1 04 00 00 48 89 c4 48 8d 6c 24 01 48 89 e7 e8 71 29 ec ff e9 0c 06 00 00 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 0f 01 ca fc 6a ff e8 b1 04 00 00 48 89 c4 48 8d 6c 24
RSP: 0018:ffffffff87207d78 EFLAGS: 000000c6
RAX: ffff8881f6e00000 RBX: ffffffff87215540 RCX: ffffffff858c50ae
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 000000000002ed24
RBP: ffffffff87207da0 R08: ffff8881f6e39733 R09: 1ffff1103edc72e6
R10: dffffc0000000000 R11: ffffed103edc72e7 R12: 1ffffffff0e42aa8
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87cb0b28
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd817b911b8 CR3: 00000000072a8000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:112 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3f/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1a0/0x470 kernel/sched/idle.c:326
 cpu_startup_entry+0x48/0x70 kernel/sched/idle.c:424
 rest_init+0x10b/0x130 init/main.c:748
 start_kernel+0x46a/0x4bb init/main.c:1135
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x6a/0x7b arch/x86/kernel/head64.c:488
 common_startup_64+0x13b/0x157
 </TASK>