linkwatch_do_dev+0x111/0x150
 __linkwatch_run_queue+0x2ab/0x710
 linkwatch_event+0x4e/0x70
------------[ 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/8403
Modules linked in:
CPU: 1 UID: 0 PID: 8403 Comm: syz-executor Tainted: G        W           6.17.0-rc3-next-20250829 #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 80 97 e2 84 e8 75 c5 e9 fe 90 <0f> 0b 90 90 e9 2b ff ff ff e8 f6 de 5f ff e9 9e fe ff ff e8 7c df
RSP: 0018:ffff88806cf08e20 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8139de70
RDX: ffff88800f535280 RSI: ffffffff8139de7e RDI: 0000000000000001
RBP: 7fffffffffffffff R08: 0000000000000001 R09: ffffed100d9e4801
R10: 0000000000000000 R11: fffffffffffdbf30 R12: ffff88800a161c00
R13: ffff88800a161c20 R14: 0000000000000002 R15: 0000000000000003
FS:  0000555568c6b400(0000) GS:ffff8880e56dd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f115ab5b178 CR3: 000000000e723000 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 f5 93 fc 48 89 ef e8 4e 40 94 fc 80 e7 02 74 06 e8 b4 48 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:ffff88803c447c30 EFLAGS: 00000286
RAX: 000000000009d9cf RBX: 0000000000000286 RCX: 0000000000000040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff84bde3bc
RBP: ffffffff85d091e0 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff8643ac57 R11: 0000000000000001 R12: 000000000007ffe0
R13: ffff88807ffdcb40 R14: ffffea00002cb900 R15: 0000000000000024
 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: 0033:0x7fd167f9f5c3
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:00007ffdef0a8f28 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ffdef0a9568 RCX: 00007fd167f9f5c3
RDX: 0000000000000004 RSI: 00007fd168055ed9 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0011cf5cc138c30a R09: 00007fd1680dc000
R10: 00007fd1680dc010 R11: 0000000000000246 R12: 00007fd167fa1b10
R13: 00007ffdef0aaee7 R14: 0000000000000000 R15: 00000000000dd053
 </TASK>
irq event stamp: 646340
hardirqs last  enabled at (646348): [<ffffffff81541b18>] __up_console_sem+0x78/0x80
hardirqs last disabled at (646357): [<ffffffff81541afd>] __up_console_sem+0x5d/0x80
softirqs last  enabled at (639282): [<ffffffff813bafcc>] handle_softirqs+0x50c/0x770
softirqs last disabled at (645585): [<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 ffff88800a161c00 pointer offset 0 size 64
percpu_ref_switch_to_atomic_rcu: percpu_ref_switch_to_atomic_rcu(): percpu_ref underflow slab kmalloc-64 start ffff88803d04f880 pointer offset 0 size 64
loop5: detected capacity change from 0 to 264192
loop0: detected capacity change from 0 to 264192
loop6: detected capacity change from 0 to 264192
vfat: Unknown parameter 'obj_user'
loop4: detected capacity change from 0 to 264192
loop7: detected capacity change from 0 to 264192
FAT-fs (loop2): invalid media value (0x08)
FAT-fs (loop2): Can't find a valid FAT filesystem
loop0: detected capacity change from 0 to 264192
vfat: Unknown parameter 'obj_user'
kmemleak: Found object by alias at 0x607f1a638234
CPU: 1 UID: 0 PID: 8414 Comm: syz-executor.2 Tainted: G        W           6.17.0-rc3-next-20250829 #1 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xca/0x120
 __lookup_object+0x94/0xb0
 delete_object_full+0x27/0x70
 free_percpu+0x30/0x1160
 futex_hash_free+0x38/0xc0
 mmput+0x2d3/0x390
 do_exit+0x79d/0x2970
 do_group_exit+0xd3/0x2a0
 __x64_sys_exit_group+0x3e/0x50
 x64_sys_call+0x18c5/0x18d0
 do_syscall_64+0xbf/0x360
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f94594c7b19
Code: Unable to access opcode bytes at 0x7f94594c7aef.
RSP: 002b:00007ffcd4887928 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001e RCX: 00007f94594c7b19
RDX: 00007f945947a72b RSI: ffffffffffffffbc RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000001b2cd25400 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffcd4887a10
 </TASK>
kmemleak: Object (percpu) 0x607f1a638230 (size 8):
kmemleak:   comm "kworker/u9:2", pid 42, jiffies 4294774726
kmemleak:   min_count = 1
kmemleak:   count = 1
kmemleak:   flags = 0x21
kmemleak:   checksum = 0
kmemleak:   backtrace:
 pcpu_alloc_noprof+0x87a/0x1170
 fib_nh_common_init+0x30/0xd0
 fib6_nh_init+0x968/0x1a00
 ip6_route_info_create_nh+0x530/0xf80
 ip6_route_add.part.0+0x59/0x170
 ip6_route_add+0x48/0x60
 addrconf_add_mroute+0x12d/0x190
 addrconf_add_dev+0x148/0x1c0
 addrconf_dev_config+0x1e9/0x430
 addrconf_notify+0xa70/0x1920
 notifier_call_chain+0xc0/0x360
 call_netdevice_notifiers_info+0xbe/0x140
 netif_state_change+0x157/0x330
 linkwatch_do_dev+0x111/0x150
 __linkwatch_run_queue+0x2ab/0x710
 linkwatch_event+0x4e/0x70
loop0: detected capacity change from 0 to 264192
vfat: Unknown parameter 'obj_user'
loop6: detected capacity change from 0 to 264192
loop4: detected capacity change from 0 to 264192
loop5: detected capacity change from 0 to 264192
----------------
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 f5 93 fc       	callq  0xfc93f525
   f:	48 89 ef             	mov    %rbp,%rdi
  12:	e8 4e 40 94 fc       	callq  0xfc944065
  17:	80 e7 02             	and    $0x2,%bh
  1a:	74 06                	je     0x22
  1c:	e8 b4 48 be fc       	callq  0xfcbe48d5
  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