------------[ cut here ]------------
WARNING: ./include/linux/ns_common.h:255 at __ns_ref_put include/linux/ns_common.h:255 [inline], CPU#1: kworker/1:3/5816
WARNING: ./include/linux/ns_common.h:255 at put_user_ns include/linux/user_namespace.h:189 [inline], CPU#1: kworker/1:3/5816
WARNING: ./include/linux/ns_common.h:255 at delayed_free_pidns+0x118/0x150 kernel/pid_namespace.c:145, CPU#1: kworker/1:3/5816
Modules linked in:
CPU: 1 UID: 0 PID: 5816 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue:  0x0 (events)
RIP: 0010:__ns_ref_put include/linux/ns_common.h:255 [inline]
RIP: 0010:put_user_ns include/linux/user_namespace.h:189 [inline]
RIP: 0010:delayed_free_pidns+0x118/0x150 kernel/pid_namespace.c:145
Code: 85 ed 7e 2b e8 99 9f 03 00 48 83 c3 a8 48 8b 3d 5e be c7 17 48 89 de 5b 41 5c 41 5e 41 5f 5d e9 1e 1e 5f 00 e8 79 9f 03 00 90 <0f> 0b 90 eb b4 e8 6e 9f 03 00 4c 89 ff be 03 00 00 00 e8 01 fb d2
RSP: 0018:ffffc90000a08bb0 EFLAGS: 00010246
RAX: ffffffff81bde0b7 RBX: ffff88801e350868 RCX: ffff88807fe05b80
RDX: 0000000000000100 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffff888058ca0193 R09: 1ffff1100b194032
R10: dffffc0000000000 R11: ffffed100b194033 R12: dffffc0000000000
R13: ffffffff81a903d7 R14: ffff888058ca0000 R15: ffff888058ca0190
FS:  0000000000000000(0000) GS:ffff888125fc2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f71b326dac0 CR3: 000000007ec32000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xcab/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x286/0x870 kernel/softirq.c:626
 __do_softirq kernel/softirq.c:660 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:727
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:743
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0xa3/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:733
RIP: 0010:finish_task_switch+0x26b/0x960 kernel/sched/core.c:5118
Code: 0f 84 3c 01 00 00 48 85 db 0f 85 63 01 00 00 e9 2f 05 00 00 4c 8b 75 d0 4c 89 e7 e8 cf df cc 09 e8 1a 56 37 00 fb 4c 8b 65 c0 <49> 8d bc 24 60 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc90003d8f958 EFLAGS: 00000282
RAX: 2236ec320b336300 RBX: 0000000000000000 RCX: 2236ec320b336300
RDX: 0000000000000000 RSI: ffffffff8d786e5e RDI: ffffffff8bbf41e0
RBP: ffffc90003d8f9b0 R08: ffffffff8f7da977 R09: 1ffffffff1efb52e
R10: dffffc0000000000 R11: fffffbfff1efb52f R12: ffff88807fe05b80
R13: dffffc0000000000 R14: ffff88807f793d00 R15: ffff8880b873af58
 context_switch kernel/sched/core.c:5267 [inline]
 __schedule+0x1850/0x4ec0 kernel/sched/core.c:6872
 __schedule_loop kernel/sched/core.c:6954 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6969
 worker_thread+0xbde/0xee0 kernel/workqueue.c:3446
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	0f 84 3c 01 00 00    	je     0x142
   6:	48 85 db             	test   %rbx,%rbx
   9:	0f 85 63 01 00 00    	jne    0x172
   f:	e9 2f 05 00 00       	jmp    0x543
  14:	4c 8b 75 d0          	mov    -0x30(%rbp),%r14
  18:	4c 89 e7             	mov    %r12,%rdi
  1b:	e8 cf df cc 09       	call   0x9ccdfef
  20:	e8 1a 56 37 00       	call   0x37563f
  25:	fb                   	sti
  26:	4c 8b 65 c0          	mov    -0x40(%rbp),%r12
* 2a:	49 8d bc 24 60 16 00 	lea    0x1660(%r12),%rdi <-- trapping instruction
  31:	00
  32:	48 89 f8             	mov    %rdi,%rax
  35:	48 c1 e8 03          	shr    $0x3,%rax
  39:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
  3e:	84 c0                	test   %al,%al