syzbot

INFO: task syz.4.72:6448 blocked for more than 143 seconds.
      Tainted: G        W           syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.72        state:D stack:25896 pid:6448  tgid:6435  ppid:5838   task_flags:0x400040 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 inode_dio_wait+0x149/0x240 fs/inode.c:2621
 bchfs_truncate+0x25a/0xc20 fs/bcachefs/fs-io.c:455
 notify_change+0xb34/0xe60 fs/attr.c:552
 do_truncate+0x1a4/0x220 fs/open.c:68
 handle_truncate fs/namei.c:3508 [inline]
 do_open fs/namei.c:3891 [inline]
 path_openat+0x3078/0x3840 fs/namei.c:4046
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_open fs/open.c:1458 [inline]
 __se_sys_open fs/open.c:1454 [inline]
 __x64_sys_open+0x11e/0x150 fs/open.c:1454
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f04fa50ebe9
RSP: 002b:00007f04f872c038 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f04fa736180 RCX: 00007f04fa50ebe9
RDX: 0000000000000000 RSI: 0000000000080242 RDI: 0000200000000040
RBP: 00007f04fa591e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f04fa736218 R14: 00007f04fa736180 R15: 00007ffe7f4452e8
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Tainted: G        W           syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 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: 8617 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:arch_atomic_try_cmpxchg arch/x86/include/asm/atomic.h:107 [inline]
RIP: 0010:raw_atomic_try_cmpxchg_acquire include/linux/atomic/atomic-arch-fallback.h:2170 [inline]
RIP: 0010:atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1302 [inline]
RIP: 0010:queued_spin_lock include/asm-generic/qspinlock.h:111 [inline]
RIP: 0010:do_raw_spin_lock+0x12e/0x290 kernel/locking/spinlock_debug.c:116
Code: 00 48 89 df be 04 00 00 00 e8 0e e5 80 00 48 8d 7c 24 40 be 04 00 00 00 e8 ff e4 80 00 8b 44 24 40 b9 01 00 00 00 f0 0f b1 0b <0f> 85 dd 00 00 00 65 8b 1d 69 03 59 10 48 b9 00 00 00 00 00 fc ff
RSP: 0018:ffffc900048e7600 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff88803e6da270 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc900048e7640
RBP: ffffc900048e76b0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200091cec8 R12: ffff88803e6da280
R13: ffff88803e6da278 R14: 1ffff11007cdb450 R15: 1ffff11007cdb44f
FS:  0000555559ca8500(0000) GS:ffff8881269c5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056348541e000 CR3: 0000000028c58000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162
 rt_mutex_slowunlock+0xb0/0x8a0 kernel/locking/rtmutex.c:1417
 spin_unlock include/linux/spinlock_rt.h:105 [inline]
 __dentry_kill+0x51b/0x660 fs/dcache.c:690
 dput+0x19f/0x2b0 fs/dcache.c:911
 debugfs_remove+0x5b/0x70 fs/debugfs/inode.c:790
 nsim_dev_hwstats_exit+0x73/0x2a0 drivers/net/netdevsim/hwstats.c:476
 nsim_dev_reload_destroy+0x2af/0x490 drivers/net/netdevsim/dev.c:1708
 nsim_drv_remove+0x58/0x160 drivers/net/netdevsim/dev.c:1722
 device_remove drivers/base/dd.c:569 [inline]
 __device_release_driver drivers/base/dd.c:1274 [inline]
 device_release_driver_internal+0x46f/0x800 drivers/base/dd.c:1297
 bus_remove_device+0x355/0x420 drivers/base/bus.c:579
 device_del+0x515/0x8e0 drivers/base/core.c:3878
 device_unregister+0x20/0xc0 drivers/base/core.c:3919
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:483 [inline]
 del_device_store+0x2aa/0x360 drivers/net/netdevsim/bus.c:244
 kernfs_fop_write_iter+0x376/0x4f0 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5d5/0xb40 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f68dc9ed69f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007ffcd74eb9c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007f68dc9ed69f
RDX: 0000000000000001 RSI: 00007ffcd74eba10 RDI: 0000000000000005
RBP: 00007f68dca730c1 R08: 0000000000000000 R09: 00007ffcd74eb817
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007ffcd74eba10 R14: 00007f68dd744620 R15: 0000000000000003
 </TASK>