syzbot

INFO: task syz.5.394:11273 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.394       state:D stack:25536 pid:11273 tgid:11272 ppid:5980   task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x1553/0x5240 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7008
 schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common kernel/sched/completion.c:121 [inline]
 wait_for_common kernel/sched/completion.c:132 [inline]
 wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153
 kthread_flush_worker+0x138/0x1a0 kernel/kthread.c:1579
 __alloc_workqueue+0xfed/0x1e90 kernel/workqueue.c:5861
 alloc_workqueue_noprof+0xe3/0x210 kernel/workqueue.c:5884
 btrfs_alloc_workqueue+0x1ec/0x2d0 fs/btrfs/async-thread.c:112
 btrfs_init_workqueues+0x2f9/0x680 fs/btrfs/disk-io.c:1953
 open_ctree+0x1598/0x4220 fs/btrfs/disk-io.c:3458
 btrfs_fill_super fs/btrfs/super.c:981 [inline]
 btrfs_get_tree_super fs/btrfs/super.c:1944 [inline]
 btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline]
 btrfs_get_tree+0x1061/0x1930 fs/btrfs/super.c:2121
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff7e6dada8a
RSP: 002b:00007ff7e4ffde58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ff7e4ffdee0 RCX: 00007ff7e6dada8a
RDX: 0000200000005100 RSI: 0000200000000040 RDI: 00007ff7e4ffdea0
RBP: 0000200000005100 R08: 00007ff7e4ffdee0 R09: 0000000000800810
R10: 0000000000800810 R11: 0000000000000246 R12: 0000200000000040
R13: 00007ff7e4ffdea0 R14: 000000000000510a R15: 0000200000000140
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/u8:0/12:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90000117c40 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90000117c40 (connector_reaper_work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
1 lock held by khungtaskd/38:
 #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8ddcb9c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/0:2/808:
2 locks held by kworker/u8:9/1011:
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888019c44138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc90005e1fc40 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc90005e1fc40 ((reaper_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
2 locks held by getty/5551:
 #0: ffff8880376e80a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by udevd/5785:
1 lock held by syz-executor/5791:
4 locks held by udevd/6333:
1 lock held by syz.5.394/11273:
 #0: ffff8880360a60d0 (&type->s_umount_key#52/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xac0 fs/super.c:345
2 locks held by syz.8.562/13388:
1 lock held by syz.6.613/13412:
3 locks held by syz.3.615/13411:
3 locks held by syz.4.616/13410:
3 locks held by dhcpcd-run-hook/13413:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 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: 13388 Comm: syz.8.562 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:clear_pages arch/x86/include/asm/page_64.h:103 [inline]
RIP: 0010:clear_page arch/x86/include/asm/page_64.h:114 [inline]
RIP: 0010:clear_highpage_kasan_tagged include/linux/highmem.h:344 [inline]
RIP: 0010:kernel_init_pages mm/page_alloc.c:1265 [inline]
RIP: 0010:post_alloc_hook+0x1b8/0x280 mm/page_alloc.c:1887
Code: 8d 48 c1 ed 03 49 c7 c6 c8 ee 7f 8d 49 c1 ee 03 eb 2f 48 8b 3d 91 17 64 0b 49 c1 e5 06 4c 29 ef 4c 01 e7 b9 00 10 00 00 31 c0 <f3> aa 0f 1f 44 00 00 49 81 c4 00 10 00 00 49 ff cf 0f 84 eb fe ff
RSP: 0018:ffffc9000789f580 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000880
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88806b44c780
RBP: 1ffffffff1affddb R08: ffffffff8f6a6eb7 R09: 0000000000000000
R10: ffffed100d689800 R11: fffffbfff1ed4dd7 R12: fffa80006b44c000
R13: fffa800000000000 R14: 1ffffffff1affdd9 R15: 0000000000000001
FS:  00007f38a2c3e6c0(0000) GS:ffff888126435000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2860c85000 CR3: 000000003a14e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x39/0xe0 mm/mempolicy.c:2509
 shmem_alloc_folio mm/shmem.c:1930 [inline]
 shmem_alloc_and_add_folio mm/shmem.c:1972 [inline]
 shmem_get_folio_gfp+0x644/0x1a80 mm/shmem.c:2567
 shmem_get_folio mm/shmem.c:2673 [inline]
 shmem_write_begin+0x166/0x320 mm/shmem.c:3327
 generic_perform_write+0x2af/0x8b0 mm/filemap.c:4319
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3502
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x629/0xba0 fs/read_write.c:688
 ksys_write+0x156/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f38a49ad04e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f38a2c3dda8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f38a2c3e6c0 RCX: 00007f38a49ad04e
RDX: 0000000001000000 RSI: 00007f389a81e000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007f38a2c3dee0 R14: 00007f38a2c3dea0 R15: 00007f389a81e000
 </TASK>