syzbot

INFO: task syz.3.4449:25117 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.4449      state:D stack:28336 pid:25117 tgid:25116 ppid:17829  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 cgroup_lock_and_drain_offline+0x51a/0x650 kernel/cgroup/cgroup.c:3275
 cgroup1_get_tree+0x9d/0x890 kernel/cgroup/cgroup-v1.c:1265
 vfs_get_tree+0x92/0x2a0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8eb839ce59
RSP: 002b:00007f8eb930d028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f8eb8615fa0 RCX: 00007f8eb839ce59
RDX: 00002000000000c0 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f8eb8432e6f R08: 00002000000001c0 R09: 0000000000000000
R10: 0000000000010012 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8eb8616038 R14: 00007f8eb8615fa0 R15: 00007ffc2c411908
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffffffff8e959c20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8e959c20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8e959c20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by syz.1.859/9729:
2 locks held by getty/14074:
 #0: ffff88803350f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900050b32e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
1 lock held by syz-executor/25277:
2 locks held by dhcpcd/26966:
 #0: ffff88804d33a260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
 #0: ffff88804d33a260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x33/0xe90 net/packet/af_packet.c:3204
 #1: ffffffff8e95ff28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
 #1: ffffffff8e95ff28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770 kernel/rcu/tree_exp.h:961

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [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:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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: 15757 Comm: kworker/1:4 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events delayed_fput
RIP: 0010:lowmem_page_address include/linux/mm.h:3007 [inline]
RIP: 0010:__free_pages_prepare mm/page_alloc.c:1413 [inline]
RIP: 0010:free_unref_folios+0x536/0x14a0 mm/page_alloc.c:3011
Code: 0c 48 c7 c7 10 cf 29 8e e8 d7 a7 0e 00 4d 89 e5 4c 2b 2d 7d 90 04 0c 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 38 80 3c 01 00 <74> 0c 48 c7 c7 00 cf 29 8e e8 ac a7 0e 00 49 c1 e5 06 4c 03 2d 41
RSP: 0018:ffffc900036f71c8 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 1ffffffff1c539e0
RDX: 0000000000000002 RSI: ffff88814c3ae000 RDI: ffff88814c3ad000
RBP: 0000000000001000 R08: ffff88814095265f R09: 1ffff1102812a4cb
R10: dffffc0000000000 R11: ffffed102812a4cc R12: ffffea000530eb40
R13: 000000000530eb40 R14: 1ffffd4000a61d6d R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888125320000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558be1e76168 CR3: 000000000e746000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 folios_put_refs+0x9e9/0xb30 mm/swap.c:1057
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 shmem_undo_range+0x4e6/0x15d0 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x280/0xa80 mm/shmem.c:1407
 evict+0x624/0xb50 fs/inode.c:825
 dentry_kill+0x1b9/0x880 fs/dcache.c:826
 finish_dput+0x1a/0x260 fs/dcache.c:1001
 __fput+0x675/0xa50 fs/file_table.c:520
 delayed_fput+0x63/0xa0 fs/file_table.c:535
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>