syzbot

INFO: task kworker/u8:7:1008 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:7    state:D stack:21240 pid:1008  tgid:1008  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x1681/0x54c0 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7282
 rxrpc_destroy_all_calls+0x44e/0x570 net/rxrpc/call_object.c:752
 rxrpc_exit_net+0x6f/0xc0 net/rxrpc/net_ns.c:112
 ops_exit_list net/core/net_namespace.c:199 [inline]
 ops_undo_list+0x49f/0x940 net/core/net_namespace.c:252
 cleanup_net+0x56e/0x800 net/core/net_namespace.c:702
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 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>

Showing all locks held in the system:
2 locks held by rcuc/1/28:
1 lock held by khungtaskd/38:
 #0: ffffffff8dfc7ec0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8dfc7ec0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8dfc7ec0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:7/1008:
 #0: ffff88801b2a0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801b2a0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc900055afc40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc900055afc40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
 #2: ffffffff8f352780 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf4/0x800 net/core/net_namespace.c:673
1 lock held by udevd/5162:
2 locks held by getty/5547:
 #0: ffff8880381ab0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003cbe2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211
10 locks held by syz-executor/16937:
9 locks held by syz-executor/16961:
1 lock held by syz.0.3485/19913:
4 locks held by syz.2.3497/19944:
1 lock held by rm/19961:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
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+0xfaa/0x1000 kernel/hung_task.c:515
 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: 19962 Comm: syz.5.3504 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:__lock_acquire+0x317/0x2cf0 kernel/locking/lockdep.c:5176
Code: 41 83 be dc 0b 00 00 00 0f 95 c2 c1 e2 0d c1 e6 0e 09 d6 8b 54 24 20 c1 e2 0f 0f b7 d2 09 f2 41 83 e5 03 41 c1 e5 10 41 09 d5 <8b> 54 24 10 83 e2 01 c1 e2 12 44 09 ea c1 e3 14 09 d3 8b 14 24 c1
RSP: 0000:ffffc90010ddf0b0 EFLAGS: 00000006
RAX: 0000000000000005 RBX: 0000000000000000 RCX: 000000000000000b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffffff81765576 R09: ffffffff8dfc7ec0
R10: ffffc90010ddf3b8 R11: ffffffff81aef0c0 R12: 0000000000000000
R13: 0000000000020000 R14: ffff8880288d8000 R15: ffff8880288d8bf8
FS:  000055558c951500(0000) GS:ffff888126221000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007effc3b12000 CR3: 000000007b4b6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1181 [inline]
 unwind_next_frame+0xc3/0x2550 arch/x86/kernel/unwind_orc.c:495
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 save_stack+0x124/0x230 mm/page_owner.c:165
 __set_page_owner+0x8d/0x4b0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1860
 prep_new_page mm/page_alloc.c:1868 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3948
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5228
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x3b/0x1e0 mm/mempolicy.c:2509
 vma_alloc_folio_noprof+0xe1/0x1e0 mm/mempolicy.c:2544
 folio_prealloc mm/memory.c:-1 [inline]
 wp_page_copy mm/memory.c:3859 [inline]
 do_wp_page+0x1109/0x3d90 mm/memory.c:4320
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault mm/memory.c:6549 [inline]
 handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6718
 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7effc3764f83
Code: 53 48 83 ec 38 80 3d 9b d0 3a 00 00 89 7c 24 18 48 89 74 24 28 0f 85 cd 09 00 00 80 3d 6a 07 ee 00 00 49 89 f1 41 89 d2 89 cb <c6> 05 76 d0 3a 00 01 41 89 d7 0f 85 45 04 00 00 80 3d 36 07 ee 00
RSP: 002b:00007fff9e223740 EFLAGS: 00010202
RAX: 00007effc3b15fa0 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000003 RSI: 00007effc3b16038 RDI: 0000000000000000
RBP: 00007effc3b15fb0 R08: 0000000000000000 R09: 00007effc3b16038
R10: 0000000000000003 R11: 0000000000000000 R12: 00007effc3b15fa0
R13: 0000200000000000 R14: 00007fff9e2237b8 R15: 00007effc3b15fa0
 </TASK>