------------[ cut here ]------------ percpu ref (io_ring_ctx_ref_free) <= 0 (0) after switching to atomic WARNING: lib/percpu-refcount.c:197 at percpu_ref_switch_to_atomic_rcu+0x3cc/0x480, CPU#1: syz-executor.7/5505 Modules linked in: CPU: 1 UID: 0 PID: 5505 Comm: syz-executor.7 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: ffff8880177c9b80 RSI: ffffffff8139de7e RDI: 0000000000000001 RBP: 7fffffffffffffff R08: 0000000000000001 R09: ffffed100d9e4801 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88800cbb8580 R13: ffff88800cbb85a0 R14: 0000000000000002 R15: 0000000000000003 FS: 0000000000000000(0000) GS:ffff8880e56dd000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2d22f000 CR3: 000000001e86b000 CR4: 0000000000350ef0 Call Trace: rcu_core+0x7c8/0x1800 handle_softirqs+0x1b1/0x770 __irq_exit_rcu+0xc4/0x100 irq_exit_rcu+0x9/0x20 sysvec_apic_timer_interrupt+0x70/0x80 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:ffff88803e0efb68 EFLAGS: 00000286 RAX: 00000000000012b3 RBX: 0000000000000246 RCX: 0000000000000040 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff84bde3bc RBP: ffffffff85d091e0 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff8643ac57 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000246 R14: ffff88800c48b140 R15: ffffea00003122c0 delete_object_full+0x46/0x70 kmem_cache_free+0x33a/0x540 exit_mmap+0x47f/0xaa0 mmput+0xd5/0x390 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: 0033:0x7fc2bc163b19 Code: Unable to access opcode bytes at 0x7fc2bc163aef. RSP: 002b:00007ffedc4d8698 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 000000000000001e RCX: 00007fc2bc163b19 RDX: 00007fc2bc11672b RSI: ffffffffffffffbc RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000001b2d621514 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffedc4d8780 irq event stamp: 5610 hardirqs last enabled at (5620): [] __up_console_sem+0x78/0x80 hardirqs last disabled at (5629): [] __up_console_sem+0x5d/0x80 softirqs last enabled at (4772): [] handle_softirqs+0x50c/0x770 softirqs last disabled at (4789): [] __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 ffff88800cbb8580 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 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