------------[ cut here ]------------
WARNING: CPU: 0 PID: 16820 at kernel/rcu/tree_stall.h:1001 rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:993
Modules linked in:
CPU: 0 PID: 16820 Comm: syz.5.3444 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:1001
Code: ff ff ff 48 c7 c7 a0 04 ef 96 be 04 00 00 00 e8 4a b9 6c 00 48 89 df b8 01 00 00 00 87 05 7c d9 7e 15 85 c0 0f 85 19 ff ff ff <0f> 0b 48 81 ff 80 51 d3 8c 74 47 48 c7 c0 1c b8 4a 8e 48 c1 e8 03
RSP: 0018:ffffc90000007bb8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffffffff8cd35180 RCX: ffffffff81702b16
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8cd35180
RBP: ffffc90000007e30 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2dde094 R12: 0000000000002904
R13: 1ffff110171c7a22 R14: 0000000000000a02 R15: dffffc0000000000
FS:  0000555586f5a500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 000000007f41e000 CR4: 00000000003506f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_core+0x612/0x1720 kernel/rcu/tree.c:2462
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:xstate_sigframe_size arch/x86/kernel/fpu/signal.c:449 [inline]
RIP: 0010:fpu__alloc_mathframe+0x61/0x130 arch/x86/kernel/fpu/signal.c:506
Code: 4c 89 e0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 e7 e8 03 83 ab 00 4d 8b 24 24 49 83 c4 04 4c 89 e0 48 c1 e8 03 42 0f b6 04 28 <84> c0 0f 85 81 00 00 00 45 8b 24 24 0f 1f 44 00 00 e8 29 2b 54 00
RSP: 0018:ffffc9000ba7fac8 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: ffffc9000ba7fb80 RCX: ffff8880226f9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ffc28926668
RBP: 0000000000000000 R08: ffff8880226fb36f R09: 1ffff110044df66d
R10: dffffc0000000000 R11: ffffed10044df66e R12: ffff8880226fb784
R13: dffffc0000000000 R14: 00007ffc28926668 R15: ffffc9000ba7fba0
 get_sigframe+0x4c1/0x7c0 arch/x86/kernel/signal.c:113
 x64_setup_rt_frame+0x158/0xcd0 arch/x86/kernel/signal_64.c:175
 setup_rt_frame arch/x86/kernel/signal.c:223 [inline]
 handle_signal arch/x86/kernel/signal.c:267 [inline]
 arch_do_signal_or_restart+0x3e5/0x780 arch/x86/kernel/signal.c:312
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f881338eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc289266e8 EFLAGS: 00000246
RAX: fffffffffffffffc RBX: 00000000000fe36e RCX: 00007f881338eec9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f88135e618c
RBP: 0000000000000032 R08: 0000000000745d1e R09: 0000000f289269df
R10: 00007ffc289267e0 R11: 0000000000000246 R12: 00007f88135e618c
R13: 00007ffc289267e0 R14: 00000000000fe3a0 R15: 00007ffc28926800
 </TASK>
----------------
Code disassembly (best guess):
   0:	4c 89 e0             	mov    %r12,%rax
   3:	48 c1 e8 03          	shr    $0x3,%rax
   7:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
   c:	74 08                	je     0x16
   e:	4c 89 e7             	mov    %r12,%rdi
  11:	e8 03 83 ab 00       	call   0xab8319
  16:	4d 8b 24 24          	mov    (%r12),%r12
  1a:	49 83 c4 04          	add    $0x4,%r12
  1e:	4c 89 e0             	mov    %r12,%rax
  21:	48 c1 e8 03          	shr    $0x3,%rax
  25:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax
* 2a:	84 c0                	test   %al,%al <-- trapping instruction
  2c:	0f 85 81 00 00 00    	jne    0xb3
  32:	45 8b 24 24          	mov    (%r12),%r12d
  36:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  3b:	e8 29 2b 54 00       	call   0x542b69