------------[ cut here ]------------
percpu ref (css_release) <= 0 (-1) after switching to atomic
WARNING: lib/percpu-refcount.c:197 at percpu_ref_switch_to_atomic_rcu+0x3cc/0x480, CPU#1: syz-executor/7685
Modules linked in:
CPU: 1 UID: 0 PID: 7685 Comm: syz-executor Tainted: G        W           6.17.0-rc4-next-20250901 #1 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x3cc/0x480
Code: 00 00 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 9e 00 00 00 49 8b 75 e8 48 c7 c7 c0 99 e2 84 e8 25 ac e9 fe 90 <0f> 0b 90 90 e9 2b ff ff ff e8 56 de 5f ff e9 9e fe ff ff e8 dc de
RSP: 0018:ffff88806cf08e20 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8139de70
RDX: ffff88801616b700 RSI: ffffffff8139de7e RDI: 0000000000000001
RBP: 7fffffffffffffff R08: 0000000000000001 R09: ffffed100d9e4801
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88800c763100
R13: ffff88800c763120 R14: 0000000000000002 R15: 0000000000000003
FS:  00005555750fb400(0000) GS:ffff8880e56d8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffce5aab000 CR3: 000000003cdee000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 rcu_core+0x7c8/0x1800
 handle_softirqs+0x1b1/0x770
 __irq_exit_rcu+0xc4/0x100
 irq_exit_rcu+0x9/0x20
 sysvec_apic_timer_interrupt+0x70/0x80
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:_raw_spin_unlock_irqrestore+0x34/0x50
Code: c7 18 53 48 89 f3 48 8b 74 24 10 e8 16 a5 93 fc 48 89 ef e8 4e f0 93 fc 80 e7 02 74 06 e8 e4 07 be fc fb 65 ff 0d 6c 4c c6 02 <74> 07 5b 5d e9 33 23 00 00 0f 1f 44 00 00 5b 5d e9 27 23 00 00 0f
RSP: 0018:ffff88800e017c30 EFLAGS: 00000286
RAX: 00000000000a7a4f RBX: 0000000000000282 RCX: 0000000000000040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff84be33bc
RBP: ffffffff85d09560 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8643b457 R11: 0000000000000001 R12: 000000000007ffe0
R13: ffff88807ffdcb40 R14: ffffea00006b5d80 R15: 0000000000000036
 kmemleak_scan+0x49a/0xe00
 kmemleak_write+0x410/0x4f0
 full_proxy_write+0x133/0x1a0
 vfs_write+0x2b7/0x1150
 ksys_write+0x121/0x240
 do_syscall_64+0xbf/0x360
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feafd9935c3
Code: 16 00 00 00 eb ae 90 b8 6e 00 00 00 eb a6 e8 44 ef 04 00 0f 1f 40 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 48 89 54 24 18
RSP: 002b:00007ffd53894728 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffd53894d68 RCX: 00007feafd9935c3
RDX: 0000000000000004 RSI: 00007feafda49ed9 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0037bfd4261c2a22 R09: 00007feafdad0000
R10: 00007feafdad0010 R11: 0000000000000246 R12: 00007feafd995b10
R13: 00007ffd53895ee7 R14: 0000000000000000 R15: 00000000000dcb00
 </TASK>
irq event stamp: 687390
hardirqs last  enabled at (687398): [<ffffffff81541b18>] __up_console_sem+0x78/0x80
hardirqs last disabled at (687407): [<ffffffff81541afd>] __up_console_sem+0x5d/0x80
softirqs last  enabled at (685192): [<ffffffff813bafcc>] handle_softirqs+0x50c/0x770
softirqs last disabled at (686673): [<ffffffff813bb364>] __irq_exit_rcu+0xc4/0x100
---[ end trace 0000000000000000 ]---
percpu_ref_switch_to_atomic_rcu: percpu_ref_switch_to_atomic_rcu(): percpu_ref underflow slab kmalloc-64 start ffff88800c763100 pointer offset 0 size 64
percpu_ref_switch_to_atomic_rcu: percpu_ref_switch_to_atomic_rcu(): percpu_ref underflow slab kmalloc-64 start ffff88803cde9180 pointer offset 0 size 64
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	18 53 48             	sbb    %dl,0x48(%rbx)
   3:	89 f3                	mov    %esi,%ebx
   5:	48 8b 74 24 10       	mov    0x10(%rsp),%rsi
   a:	e8 16 a5 93 fc       	callq  0xfc93a525
   f:	48 89 ef             	mov    %rbp,%rdi
  12:	e8 4e f0 93 fc       	callq  0xfc93f065
  17:	80 e7 02             	and    $0x2,%bh
  1a:	74 06                	je     0x22
  1c:	e8 e4 07 be fc       	callq  0xfcbe0805
  21:	fb                   	sti
  22:	65 ff 0d 6c 4c c6 02 	decl   %gs:0x2c64c6c(%rip)        # 0x2c64c95
* 29:	74 07                	je     0x32 <-- trapping instruction
  2b:	5b                   	pop    %rbx
  2c:	5d                   	pop    %rbp
  2d:	e9 33 23 00 00       	jmpq   0x2365
  32:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  37:	5b                   	pop    %rbx
  38:	5d                   	pop    %rbp
  39:	e9 27 23 00 00       	jmpq   0x2365
  3e:	0f                   	.byte 0xf