------------[ cut here ]------------ WARNING: CPU: 2 PID: 58 at kernel/rcu/tree_stall.h:989 rcu_check_gp_start_stall.part.0+0x1c4/0x4b0 kernel/rcu/tree_stall.h:989 Modules linked in: CPU: 2 UID: 0 PID: 58 Comm: kworker/2:1 Not tainted 6.13.0-rc3-syzkaller-00026-g59dbb9d81adf #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Workqueue: events fqdir_free_fn RIP: 0010:rcu_check_gp_start_stall.part.0+0x1c4/0x4b0 kernel/rcu/tree_stall.h:989 Code: 88 61 01 00 00 be 04 00 00 00 48 c7 c7 60 39 3b 9a e8 00 31 7c 00 b8 01 00 00 00 87 05 35 a0 bb 18 85 c0 0f 85 3d 01 00 00 90 <0f> 0b 90 48 81 fd 00 5f dc 8d 48 c7 c3 d4 10 1d 90 74 5a 48 b8 00 RSP: 0018:ffffc90000548df0 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000002904 RCX: ffffffff817f9920 RDX: fffffbfff347672c RSI: 0000000000000004 RDI: ffffffff9a3b3960 RBP: ffffffff8ddc5f00 R08: 0000000000000001 R09: fffffbfff347672c R10: 0000000000000003 R11: 0000000000000003 R12: 1ffffffff1b42040 R13: 0000000000000246 R14: ffffffff8ddc5f00 R15: ffff88802b63fcd2 FS: 0000000000000000(0000) GS:ffff88802b600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020001000 CR3: 000000004c810000 CR4: 0000000000352ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_check_gp_start_stall kernel/rcu/tree_stall.h:952 [inline] rcu_core+0x4d0/0x14d0 kernel/rcu/tree.c:2818 handle_softirqs+0x213/0x8f0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0x109/0x170 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_single+0x1c7/0x580 kernel/smp.c:679 Code: c0 48 89 de 89 fa c1 e2 10 09 d0 89 44 24 4c e8 af fa ff ff 41 89 c5 0f 1f 44 00 00 e8 32 e2 0b 00 eb 07 e8 2b e2 0b 00 f3 90 <8b> 5c 24 48 31 ff 83 e3 01 89 de e8 59 e4 0b 00 85 db 75 e5 e8 10 RSP: 0018:ffffc90000797b40 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff818d6cd7 RDX: ffff88801e930000 RSI: ffffffff818d6cc5 RDI: 0000000000000005 RBP: ffffc90000797c08 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000003 R12: 1ffff920000f2f6c R13: 0000000000000000 R14: 0000000000000001 R15: ffff88802b43fcc0 rcu_barrier+0x28d/0x700 kernel/rcu/tree.c:4617 fqdir_free_fn+0x32/0x130 net/ipv4/inet_fragment.c:167 process_one_work+0x958/0x1b30 kernel/workqueue.c:3229 process_scheduled_works kernel/workqueue.c:3310 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 ---------------- Code disassembly (best guess): 0: c0 48 89 de rorb $0xde,-0x77(%rax) 4: 89 fa mov %edi,%edx 6: c1 e2 10 shl $0x10,%edx 9: 09 d0 or %edx,%eax b: 89 44 24 4c mov %eax,0x4c(%rsp) f: e8 af fa ff ff call 0xfffffac3 14: 41 89 c5 mov %eax,%r13d 17: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 1c: e8 32 e2 0b 00 call 0xbe253 21: eb 07 jmp 0x2a 23: e8 2b e2 0b 00 call 0xbe253 28: f3 90 pause * 2a: 8b 5c 24 48 mov 0x48(%rsp),%ebx <-- trapping instruction 2e: 31 ff xor %edi,%edi 30: 83 e3 01 and $0x1,%ebx 33: 89 de mov %ebx,%esi 35: e8 59 e4 0b 00 call 0xbe493 3a: 85 db test %ebx,%ebx 3c: 75 e5 jne 0x23 3e: e8 .byte 0xe8 3f: 10 .byte 0x10