------------[ cut here ]------------
WARNING: ./include/linux/ns_common.h:255 at __ns_ref_put include/linux/ns_common.h:255 [inline], CPU#1: syz.3.17/5982
WARNING: ./include/linux/ns_common.h:255 at put_user_ns include/linux/user_namespace.h:189 [inline], CPU#1: syz.3.17/5982
WARNING: ./include/linux/ns_common.h:255 at delayed_free_pidns+0x118/0x150 kernel/pid_namespace.c:145, CPU#1: syz.3.17/5982
Modules linked in:
CPU: 1 UID: 0 PID: 5982 Comm: syz.3.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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: 0000:ffffc90000a08bb0 EFLAGS: 00010246
RAX: ffffffff81bde0b7 RBX: ffff8880281ac5b8 RCX: ffff88801dbabd00
RDX: 0000000000000100 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 0000000000000002 R08: ffff88807be70193 R09: 1ffff1100f7ce032
R10: dffffc0000000000 R11: ffffed100f7ce033 R12: dffffc0000000000
R13: ffffffff81a903d7 R14: ffff88807be70000 R15: ffff88807be70190
FS:  0000555566aeb500(0000) GS:ffff888125fc2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f27a7dd22e8 CR3: 0000000078722000 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_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:should_fail_alloc_page+0x4/0x100 mm/fail_page_alloc.c:27
Code: 75 ff ff 31 c0 eb 85 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 <55> 41 57 41 56 53 89 f5 89 fb e8 9d b5 98 ff 44 8b 35 4a 41 dd 0b
RSP: 0000:ffffc9000a747788 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc9000a747840 RCX: cdeb31bb77d67200
RDX: ffff88801dbabd00 RSI: 0000000000000000 RDI: 0000000000140dca
RBP: 0000000000000008 R08: 0000000000000000 R09: ffffffff821a397d
R10: ffffc9000a747840 R11: fffff520014e8f0d R12: 1ffff920014e8f03
R13: ffff88801dbabd2c R14: 0000000000140dca R15: 1ffff920014e8f08
 prepare_alloc_pages+0x22b/0x650 mm/page_alloc.c:4989
 __alloc_frozen_pages_noprof+0x123/0x370 mm/page_alloc.c:5198
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof mm/mempolicy.c:2505 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2540
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 wp_page_copy mm/memory.c:3727 [inline]
 do_wp_page+0x1231/0x5800 mm/memory.c:4188
 handle_pte_fault mm/memory.c:6258 [inline]
 __handle_mm_fault mm/memory.c:6389 [inline]
 handle_mm_fault+0x14c8/0x32a0 mm/memory.c:6558
 do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f27a7a4d75c
Code: 23 83 c0 01 44 39 d0 75 dc 48 89 f0 25 ff 1f 00 00 49 89 34 c1 41 88 3c 00 31 c0 c3 66 90 41 38 3c 10 74 0b 41 88 3c 10 31 c0 <49> 89 34 d1 c3 b8 01 00 00 00 c3 66 0f 1f 84 00 00 00 00 00 48 83
RSP: 002b:00007ffcf18e02a8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00007f27a8915720 RCX: 0000000000000000
RDX: 000000000000005d RSI: ffffffff820f805d RDI: 0000000000000000
RBP: ffffffff820f805d R08: 00007f27a7dd0000 R09: 00007f27a7dd2000
R10: 00000000820f8061 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff820f8562 R15: 0000000000000002
 </TASK>
----------------
Code disassembly (best guess):
   0:	75 ff                	jne    0x1
   2:	ff 31                	push   (%rcx)
   4:	c0 eb 85             	shr    $0x85,%bl
   7:	cc                   	int3
   8:	cc                   	int3
   9:	cc                   	int3
   a:	cc                   	int3
   b:	cc                   	int3
   c:	cc                   	int3
   d:	cc                   	int3
   e:	cc                   	int3
   f:	cc                   	int3
  10:	cc                   	int3
  11:	cc                   	int3
  12:	cc                   	int3
  13:	cc                   	int3
  14:	cc                   	int3
  15:	cc                   	int3
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	90                   	nop
  1f:	90                   	nop
  20:	90                   	nop
  21:	90                   	nop
  22:	90                   	nop
  23:	90                   	nop
  24:	90                   	nop
  25:	90                   	nop
  26:	0f 1f 40 d6          	nopl   -0x2a(%rax)
* 2a:	55                   	push   %rbp <-- trapping instruction
  2b:	41 57                	push   %r15
  2d:	41 56                	push   %r14
  2f:	53                   	push   %rbx
  30:	89 f5                	mov    %esi,%ebp
  32:	89 fb                	mov    %edi,%ebx
  34:	e8 9d b5 98 ff       	call   0xff98b5d6
  39:	44 8b 35 4a 41 dd 0b 	mov    0xbdd414a(%rip),%r14d        # 0xbdd418a