syzbot

INFO: task udevd:4644 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:25056 pid: 4644 ppid:  3561 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 device_lock include/linux/device.h:764 [inline]
 uevent_show+0x17a/0x330 drivers/base/core.c:2408
 dev_attr_show+0x50/0xb0 drivers/base/core.c:2110
 sysfs_kf_seq_show+0x316/0x4c0 fs/sysfs/file.c:61
 seq_read_iter+0x49b/0xd50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2166 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x725/0xcf0 fs/read_write.c:485
 ksys_read+0x14d/0x250 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f2451525407
RSP: 002b:00007ffc257c92d0 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f2451437880 RCX: 00007f2451525407
RDX: 0000000000001000 RSI: 000055c87013da00 RDI: 0000000000000008
RBP: 00007f245166dff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007f245166dea0 R14: 0000000000000000 R15: 000055c8701400d0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
6 locks held by kworker/0:2/1108:
 #0: ffff88801b9ced38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc900049e7d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff88814844a220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #2: ffff88814844a220 (&dev->mutex){....}-{3:3}, at: hub_event+0x1a7/0x5560 drivers/usb/core/hub.c:5827
 #3: ffff888079523220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff888079523220 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x107/0x8a0 drivers/usb/core/hub.c:2278
 #4: ffff8880248771a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #4: ffff8880248771a8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1044 [inline]
 #4: ffff8880248771a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb0/0x750 drivers/base/dd.c:1259
 #5: ffff8880501fc188 (&hdw->big_lock_mutex){+.+.}-{3:3}, at: pvr2_hdw_disconnect+0x69/0x500 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2710
2 locks held by pvrusb2-context/2425:
 #0: ffff8880501fc188 (&hdw->big_lock_mutex){+.+.}-{3:3}, at: pvr2_hdw_initialize+0xc3/0x3a80 drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2326
 #1: ffffffff8bfccf90 (umhelper_sem){++++}-{3:3}, at: usermodehelper_read_trylock+0xe7/0x320 kernel/umh.c:217
2 locks held by getty/3945:
 #0: ffff88814d2c5098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
3 locks held by kworker/0:3/4183:
 #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90002eafd00 ((work_completion)(&pwq->unbound_release_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8c1211a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #2: ffffffff8c1211a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x347/0x6b0 kernel/rcu/tree_exp.h:845
4 locks held by udevd/4644:
 #0: ffff888023561790 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff888062d4a488 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff88801ee25ae8 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff888079523220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff888079523220 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
1 lock held by syz.4.1169/8454:
2 locks held by syz.3.1171/8458:
 #0: ffffffff8bfddd48 (sched_core_mutex){+.+.}-{3:3}, at: sched_core_get+0x49/0x1d0 kernel/sched/core.c:329
 #1: ffffffff8c1211a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 #1: ffffffff8c1211a8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x320/0x6b0 kernel/rcu/tree_exp.h:845

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8454 Comm: syz.4.1169 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:205
Code: 84 00 00 00 00 00 53 48 89 fb e8 17 00 00 00 48 8b 3d 10 d2 f1 0b 48 89 de 5b e9 07 9e 43 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d 24 a5 8a 7e 65 8b 15 25 a5 8a 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc9000305f220 EFLAGS: 00000046
RAX: ffffffff819c56be RBX: ffffea000163dc08 RCX: ffff8880290b3b80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: dffffc0000000000 R09: fffffbfff1ad334e
R10: fffffbfff1ad334e R11: 1ffffffff1ad334d R12: 0000000000000000
R13: dffffc0000000000 R14: ffffea000151dcc0 R15: ffffea000151dcc8
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555555ff15c8 CR3: 00000000632d3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 _compound_head include/linux/page-flags.h:198 [inline]
 PageSwapBacked include/linux/page-flags.h:371 [inline]
 unaccount_page_cache_page+0x33e/0x870 mm/filemap.c:197
 __delete_from_page_cache+0xbf/0x6b0 mm/filemap.c:231
 delete_from_page_cache+0x121/0x190 mm/filemap.c:266
 truncate_inode_page+0x8d/0xb0 mm/truncate.c:219
 shmem_undo_range+0x4dc/0x1880 mm/shmem.c:960
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x20d/0xa00 mm/shmem.c:1145
 evict+0x485/0x870 fs/inode.c:647
 __dentry_kill+0x431/0x650 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5ee/0x930 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x61e/0x20a0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbcff45ffc9
Code: Unable to access opcode bytes at RIP 0x7fbcff45ff9f.
RSP: 002b:00007fbcfd685038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: 0000000000010106 RBX: 00007fbcff6b7090 RCX: 00007fbcff45ffc9
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000006
RBP: 00007fbcff4e2f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbcff6b7128 R14: 00007fbcff6b7090 R15: 00007ffdd4ebfbf8
 </TASK>