syzbot

INFO: task udevd:5895 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:23048 pid:5895  ppid:5136   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 io_schedule+0x80/0xd0 kernel/sched/core.c:9023
 folio_wait_bit_common+0x714/0xfa0 mm/filemap.c:1329
 folio_put_wait_locked mm/filemap.c:1493 [inline]
 do_read_cache_folio+0x1c0/0x7d0 mm/filemap.c:3786
 read_mapping_folio include/linux/pagemap.h:898 [inline]
 read_part_sector+0xd2/0x340 block/partitions/core.c:718
 adfspart_check_POWERTEC+0x93/0xed0 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+0x740/0x1420 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+0x27f1/0x3230 fs/namei.c:3797
 do_filp_open+0x1f5/0x430 fs/namei.c:3824
 do_sys_openat2+0x134/0x1d0 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:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ffbb30a7407
RSP: 002b:00007fff7f4058a0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ffbb3795880 RCX: 00007ffbb30a7407
RDX: 00000000000a0800 RSI: 000055ffe55d0430 RDI: ffffffffffffff9c
RBP: 000055ffe55cf910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055ffe55d7650
R13: 000055ffe55e7410 R14: 0000000000000000 R15: 000055ffe55d7650
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d1320a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:4/59:
1 lock held by dhcpcd/5431:
 #0: ffff8880b8f3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
1 lock held by dhcpcd/5432:
2 locks held by getty/5525:
 #0: ffff88802d69c0a0 (&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+0x433/0x1390 drivers/tty/n_tty.c:2217
2 locks held by kworker/1:4/5804:
 #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #0: ffff888017c72538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
 #1: ffffc900044c7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2628 [inline]
 #1: ffffc900044c7d00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x96f/0x15d0 kernel/workqueue.c:2730
1 lock held by udevd/5895:
 #0: ffff888021e404c8 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x121/0x600 block/bdev.c:805
2 locks held by dhcpcd/26040:
 #0: ffff8880474b6130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
 #0: ffff8880474b6130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3259
 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:292 [inline]
 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x306/0x880 kernel/rcu/tree_exp.h:1004
2 locks held by dhcpcd/26041:
 #0: ffff888058a00130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
 #0: ffff888058a00130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3259
 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #1: ffffffff8d137a78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3da/0x880 kernel/rcu/tree_exp.h:1004
1 lock held by dhcpcd/26042:
 #0: ffff88807cac6130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
 #0: ffff88807cac6130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3259
1 lock held by dhcpcd/26043:
 #0: ffff88807a518130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
 #0: ffff88807a518130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3259
1 lock held by dhcpcd/26044:
 #0: ffff88801ef00130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1780 [inline]
 #0: ffff88801ef00130 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x32/0xcc0 net/packet/af_packet.c:3259
1 lock held by sed/26050:

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

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 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 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+0xf3d/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: 26045 Comm: dhcpcd-run-hook Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__sanitizer_cov_trace_switch+0x84/0x120 kernel/kcov.c:349
Code: b9 01 00 00 00 48 85 c0 0f 84 ae 00 00 00 41 57 41 56 41 54 53 48 8b 54 24 20 65 4c 8b 05 84 8e 7c 7e 45 31 c9 eb 08 49 ff c1 <4c> 39 c8 74 77 4e 8b 54 ce 10 65 44 8b 1d 72 8e 7c 7e 41 81 e3 00
RSP: 0018:ffffc90003ac72b0 EFLAGS: 00000203
RAX: 0000000000000008 RBX: 0000000000000000 RCX: 0000000000000003
RDX: ffffffff813b3f02 RSI: ffffffff8cfa07a0 RDI: 0000000000000005
RBP: ffffc90003ac73f8 R08: ffff888029793c00 R09: 0000000000000007
R10: 0000000000000008 R11: 0000000000000000 R12: ffffc90003ac73a8
R13: dffffc0000000000 R14: 0000000000000005 R15: ffffffff8f19c2fe
FS:  00007fa8d2c0cc80(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe4c8d90a8 CR3: 0000000064416000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 unwind_next_frame+0x742/0x2970 arch/x86/kernel/unwind_orc.c:515
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4b0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x11a/0x2d0 mm/slub.c:3519
 vma_lock_alloc kernel/fork.c:460 [inline]
 vm_area_dup+0x61/0x270 kernel/fork.c:513
 dup_mmap kernel/fork.c:711 [inline]
 dup_mm kernel/fork.c:1693 [inline]
 copy_mm+0xcd5/0x1d80 kernel/fork.c:1742
 copy_process+0x16f7/0x3d80 kernel/fork.c:2507
 kernel_clone+0x24b/0x8a0 kernel/fork.c:2915
 __do_sys_clone kernel/fork.c:3058 [inline]
 __se_sys_clone kernel/fork.c:3042 [inline]
 __x64_sys_clone+0x1b7/0x230 kernel/fork.c:3042
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa8d2da6636
Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffe4c8d8c10 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffe4c8d8c18 RCX: 00007fa8d2da6636
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00005616da32ec30 R08: 0000000000000000 R09: 0000000000000030
R10: 00007fa8d2c0cf50 R11: 0000000000000246 R12: 00005616da33c290
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>