------------[ cut here ]------------
1
WARNING: kernel/rcu/tree_stall.h:1063 at rcu_check_gp_start_stall+0x2e4/0x470 kernel/rcu/tree_stall.h:1063, CPU#0: syz.5.3054/16429
Modules linked in:
CPU: 0 UID: 0 PID: 16429 Comm: syz.5.3054 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026
RIP: 0010:rcu_check_gp_start_stall+0x2e4/0x470 kernel/rcu/tree_stall.h:1063
Code: ff ff 48 c7 c7 c0 76 a1 9a be 04 00 00 00 e8 93 a3 8a 00 4c 89 f7 b8 01 00 00 00 87 05 15 9c f4 18 85 c0 0f 85 17 ff ff ff 90 <0f> 0b 90 48 81 ff 40 23 d6 8e 74 47 48 c7 c0 80 33 7a 90 48 c1 e8
RSP: 0018:ffffc90000007d78 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000246 RCX: ffffffff81acda9d
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8ed62340
RBP: ffffc90000007f20 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff3542ed8 R12: 0000000000002904
R13: dffffc0000000000 R14: ffffffff8ed62340 R15: dffffc0000000000
FS:  00007fb4bdfef6c0(0000) GS:ffff888124ce0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2e507ff8 CR3: 0000000029975000 CR4: 0000000000350ef0
Call Trace:
 <IRQ>
 rcu_core+0x5c6/0x1260 kernel/rcu/tree.c:2914
 handle_softirqs+0x226/0x860 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0xcb/0x220 kernel/softirq.c:767
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:784
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:do_sigaltstack kernel/signal.c:4411 [inline]
RIP: 0010:restore_altstack+0x1dd/0x4f0 kernel/signal.c:4467
Code: 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 ef e8 95 39 ab 00 4d 8b 6d 00 4c 89 f7 4c 89 ee e8 66 74 3b 00 4d 39 ee <0f> 86 b0 02 00 00 e8 88 71 3b 00 eb 0c e8 81 71 3b 00 eb 0f e8 7a
RSP: 0018:ffffc900038d7b80 EFLAGS: 00000202
RAX: ffffffff818c420a RBX: ffff88807faa9f40 RCX: ffff88807faa9f40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 00007fb4bdfeeb40
RBP: ffffc900038d7c90 R08: ffffc900038d7c17 R09: 1ffff9200071af82
R10: dffffc0000000000 R11: fffff5200071af83 R12: 1ffff9200071af7c
R13: 0000000000000000 R14: 00007fb4bdfeeb40 R15: 0000000000000002
 __ia32_sys_rt_sigreturn+0x2bd/0x8c0 arch/x86/kernel/signal_64.c:265
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb4bd13f4d9
Code: 11 06 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 0c 25
RSP: 002b:00007fb4bdfeeb40 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007fb4bd425fa8 RCX: 00007fb4bd13f4d9
RDX: 00007fb4bdfeeb40 RSI: 00007fb4bdfeec70 RDI: 0000000000000011
RBP: 00007fb4bd425fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4bd426038 R14: 00007fffcb012e50 R15: 00007fffcb012f38
 </TASK>
----------------
Code disassembly (best guess):
   0:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
   7:	fc ff df
   a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1)
   e:	74 08                	je     0x18
  10:	4c 89 ef             	mov    %r13,%rdi
  13:	e8 95 39 ab 00       	call   0xab39ad
  18:	4d 8b 6d 00          	mov    0x0(%r13),%r13
  1c:	4c 89 f7             	mov    %r14,%rdi
  1f:	4c 89 ee             	mov    %r13,%rsi
  22:	e8 66 74 3b 00       	call   0x3b748d
  27:	4d 39 ee             	cmp    %r13,%r14
* 2a:	0f 86 b0 02 00 00    	jbe    0x2e0 <-- trapping instruction
  30:	e8 88 71 3b 00       	call   0x3b71bd
  35:	eb 0c                	jmp    0x43
  37:	e8 81 71 3b 00       	call   0x3b71bd
  3c:	eb 0f                	jmp    0x4d
  3e:	e8                   	.byte 0xe8
  3f:	7a                   	.byte 0x7a