syzbot

INFO: task udevd:6586 blocked for more than 142 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24968 pid:6586  ppid:5158   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 io_schedule+0x80/0xd0 kernel/sched/core.c:9022
 folio_wait_bit_common+0x6eb/0xf70 mm/filemap.c:1329
 folio_put_wait_locked mm/filemap.c:1493 [inline]
 do_read_cache_folio+0x1c0/0x7e0 mm/filemap.c:3786
 read_mapping_folio include/linux/pagemap.h:898 [inline]
 read_part_sector+0xd2/0x350 block/partitions/core.c:718
 adfspart_check_POWERTEC+0x8d/0xf00 block/partitions/acorn.c:454
 check_partition block/partitions/core.c:138 [inline]
 blk_add_partitions block/partitions/core.c:600 [inline]
 bdev_disk_changed+0x73a/0x1410 block/partitions/core.c:689
 blkdev_get_whole+0x30d/0x390 block/bdev.c:672
 blkdev_get_by_dev+0x279/0x600 block/bdev.c:814
 blkdev_open+0x152/0x360 block/fops.c:589
 do_dentry_open+0x8c6/0x1500 fs/open.c:929
 do_open fs/namei.c:3640 [inline]
 path_openat+0x274b/0x3190 fs/namei.c:3797
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1421
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f759cea7407
RSP: 002b:00007ffe6baf48f0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f759d5da880 RCX: 00007f759cea7407
RDX: 00000000000a0800 RSI: 000055db4fe7c0f0 RDI: ffffffffffffff9c
RBP: 000055db4fe64910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055db4fe6bc60
R13: 000055db4fe7c410 R14: 0000000000000000 R15: 000055db4fe6bc60
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by getty/5550:
 #0: ffff888030b5a0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
1 lock held by syz-executor/5787:
2 locks held by syz-executor/5793:
3 locks held by kworker/u4:9/5881:
 #0: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x20ee/0x44d0 kernel/sched/core.c:6694
 #2: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
1 lock held by udevd/6586:
 #0: ffff8881427344c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:805
1 lock held by udevd/6948:
 #0: ffff8880217184c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:805
2 locks held by syz.2.603/8903:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8903 Comm: syz.2.603 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_preemption_disabled+0x18/0x110 lib/smp_processor_id.c:14
Code: 60 6f fc 8a eb 0c 66 2e 0f 1f 84 00 00 00 00 00 66 90 55 41 57 41 56 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 08 <65> 8b 05 ad 82 94 75 65 8b 0d a2 82 94 75 f7 c1 ff ff ff 7f 74 1f
RSP: 0018:ffffc9000458ec70 EFLAGS: 00000082
RAX: 743d2c99378a7b00 RBX: ffff88801d2b3c00 RCX: 743d2c99378a7b00
RDX: 0000000000000000 RSI: ffffffff8aaac9c0 RDI: ffffffff8afc6f80
RBP: 00000000ffffffff R08: ffffffff8e4a93ef R09: 1ffffffff1c9527d
R10: dffffc0000000000 R11: fffffbfff1c9527e R12: ffff88801d2b3c00
R13: 0000000000000046 R14: ffff8880b8e3c018 R15: 00000000ffffffff
FS:  00007f741c7866c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5b439b7198 CR3: 00000000691df000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 lockdep_recursion_inc kernel/locking/lockdep.c:462 [inline]
 lock_is_held_type+0x79/0x190 kernel/locking/lockdep.c:5824
 lock_is_held include/linux/lockdep.h:288 [inline]
 lockdep_assert_rq_held kernel/sched/sched.h:1363 [inline]
 cpuacct_charge+0xe0/0x310 kernel/sched/cpuacct.c:339
 cgroup_account_cputime include/linux/cgroup.h:719 [inline]
 update_curr_task+0xe5/0x300 kernel/sched/fair.c:1180
 update_curr+0x4a6/0x7f0 kernel/sched/fair.c:1218
 put_prev_entity+0x3d/0x200 kernel/sched/fair.c:5510
 put_prev_task_fair+0x4b/0x70 kernel/sched/fair.c:8584
 put_prev_task kernel/sched/sched.h:2306 [inline]
 put_prev_task_balance kernel/sched/core.c:5984 [inline]
 pick_next_task kernel/sched/core.c:6119 [inline]
 __schedule+0x2789/0x44d0 kernel/sched/core.c:6661
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 follow_page_pte+0xb79/0x1a70 mm/gup.c:594
 __get_user_pages+0x570/0x1470 mm/gup.c:1165
 __get_user_pages_locked mm/gup.c:1431 [inline]
 get_dump_page+0x103/0x200 mm/gup.c:1939
 dump_user_range+0x12c/0x800 fs/coredump.c:982
 elf_core_dump+0x3114/0x36e0 fs/binfmt_elf.c:2184
 do_coredump+0x1755/0x2480 fs/coredump.c:833
 get_signal+0x1133/0x1400 kernel/signal.c:2888
 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:315
 exc_page_fault+0x8f/0x110 arch/x86/mm/fault.c:1524
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f741b98f751
Code: 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 48 3d 01 f0 ff ff 73 01 <c3> 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f741bbe6090 RCX: 00007f741b98f749
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f741ba13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f741bbe6128 R14: 00007f741bbe6090 R15: 00007ffdee43b268
 </TASK>