------------[ cut here ]------------
percpu ref (free_ioctx_reqs) <= 0 (0) after switching to atomic
WARNING: lib/percpu-refcount.c:197 at percpu_ref_switch_to_atomic_rcu+0x3cc/0x480, CPU#1: syz-fuzzer/254
Modules linked in:
CPU: 1 UID: 0 PID: 254 Comm: syz-fuzzer 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: 0000:ffff88801a19fd68 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8139de70
RDX: ffff8880144a3700 RSI: ffffffff8139de7e RDI: 0000000000000001
RBP: 8000000000000000 R08: 0000000000000001 R09: ffffed100d9e4801
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88800d629580
R13: ffff88800d6295a0 R14: 0000000000000002 R15: 0000000000000003
FS:  000000c000030790(0000) GS:ffff8880e56d8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc0ec0db038 CR3: 000000001f679000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 rcu_core+0x7c8/0x1800
 handle_softirqs+0x1b1/0x770
 __irq_exit_rcu+0xc4/0x100
 irq_exit_rcu+0x9/0x20
 sysvec_apic_timer_interrupt+0x39/0x80
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0033:0x5c132e
Code: 89 4c 24 50 31 db eb 12 48 8b b4 24 d0 00 00 00 48 83 c6 10 48 89 f0 48 89 cb 48 89 84 24 d0 00 00 00 48 89 5c 24 40 48 8b 08 <48> 8b 50 08 48 89 0c 24 48 89 54 24 08 48 8b 8c 24 10 01 00 00 48
RSP: 002b:000000c002be28a8 EFLAGS: 00000246
RAX: 000000c0013e8fc0 RBX: 0000000000000000 RCX: 0000000000ea89c0
RDX: 000000c0035abd80 RSI: 0000000000000060 RDI: 0000000000000060
RBP: 000000c002be2998 R08: 00007fc0f6d28cda R09: 0000000000203000
R10: 000000000000000c R11: 00000000000000fa R12: 00000000000000fa
R13: 00aaaaaaaaaaaaaa R14: 0000000000e5dabc R15: 0000000000000038
 </TASK>
irq event stamp: 206238
hardirqs last  enabled at (206246): [<ffffffff81541b18>] __up_console_sem+0x78/0x80
hardirqs last disabled at (206255): [<ffffffff81541afd>] __up_console_sem+0x5d/0x80
softirqs last  enabled at (205796): [<ffffffff812ccddb>] __fpu_restore_sig+0x59b/0x1210
softirqs last disabled at (205825): [<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 ffff88800d629580 pointer offset 0 size 64
kmemleak: Found object by alias at 0x607f1a63e174
CPU: 1 UID: 0 PID: 4036 Comm: syz-executor.4 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
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
 get_signal+0x2315/0x2340
 arch_do_signal_or_restart+0x80/0x790
 exit_to_user_mode_loop+0x8b/0x110
 do_syscall_64+0x2f7/0x360
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f73569fbb19
Code: Unable to access opcode bytes at 0x7f73569fbaef.
RSP: 002b:00007f7353f2f188 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
RAX: fffffffffffffe00 RBX: 00007f7356b0f0e0 RCX: 00007f73569fbb19
RDX: 000000000000008d RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00007f7356a55f6d R08: 0000000020000000 R09: 0000000000000080
R10: 0000000000010000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd8334305f R14: 00007f7353f2f300 R15: 0000000000022000
 </TASK>
kmemleak: Object (percpu) 0x607f1a63e170 (size 8):
kmemleak:   comm "syz-executor.2", pid 4010, jiffies 4294811227
kmemleak:   min_count = 1
kmemleak:   count = 0
kmemleak:   flags = 0x21
kmemleak:   checksum = 0
kmemleak:   backtrace:
 pcpu_alloc_noprof+0x87a/0x1170
 percpu_ref_init+0x37/0x400
 blkg_alloc+0xe9/0x7d0
 blkg_create+0xe08/0x1420
 bio_associate_blkg_from_css+0xe06/0x1380
 bio_associate_blkg+0x10e/0x2a0
 bio_init+0x2dd/0x570
 bio_alloc_bioset+0x4c5/0x8c0
 ext4_bio_write_folio+0x8d6/0x13c0
 mpage_map_and_submit_buffers+0x545/0x9d0
 ext4_do_writepages+0x2125/0x38b0
 ext4_writepages+0x369/0x7a0
 do_writepages+0x244/0x5c0
 filemap_fdatawrite_wbc+0x10b/0x150
 __filemap_fdatawrite_range+0xb9/0x100
 filemap_write_and_wait_range.part.0+0x89/0x110