syzbot


WARNING in rcu_check_gp_start_stall (3)

Status: upstream: reported on 2025/07/02 22:12
Reported-by: syzbot+609c0a640d7f2888e15b@syzkaller.appspotmail.com
First crash: 110d, last: 41d
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in rcu_check_gp_start_stall net -1 C done error 2717 42m 2432d 0/29 upstream: reported C repro on 2019/02/22 17:10
linux-6.6 WARNING in rcu_check_gp_start_stall origin:lts-only -1 C 77 2d11h 125d 0/2 upstream: reported C repro on 2025/06/17 13:49
linux-5.15 WARNING in rcu_check_gp_start_stall (2) -1 7 400d 544d 0/3 auto-obsoleted due to no activity on 2024/12/25 11:45
linux-5.15 WARNING in rcu_check_gp_start_stall -1 1 683d 683d 0/3 auto-obsoleted due to no activity on 2024/03/17 09:39
linux-6.1 WARNING in rcu_check_gp_start_stall origin:upstream missing-backport -1 C done 19 20d 764d 0/3 upstream: reported C repro on 2023/09/17 20:24

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/rcu/tree_stall.h:937 rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:929
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:937
Code: ff ff ff 48 c7 c7 20 6c 10 96 be 04 00 00 00 e8 da 06 58 00 48 89 df b8 01 00 00 00 87 05 5c 3e ac 14 85 c0 0f 85 19 ff ff ff <0f> 0b 48 81 ff c0 08 12 8c 74 47 48 c7 c0 c4 c2 69 8d 48 c1 e8 03
RSP: 0018:ffffc90000007bb8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffffffff8c1208c0 RCX: ffffffff81642db6
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8c1208c0
RBP: ffffc90000007e10 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2c20d84 R11: 1ffffffff2c20d84 R12: 0000000000002904
R13: ffffffff8c1208c0 R14: 0000000000000a02 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcb028b1f4e CR3: 000000007d375000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_core+0x5ef/0x15d0 kernel/rcu/tree.c:2758
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:730
Code: bf 48 89 df e8 46 f5 09 f8 eb b5 e8 3f b0 f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d f7 83 53 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8be07dc8 EFLAGS: 000002c6
RAX: caa11c2bced69b00 RBX: ffffffff8bebc3c0 RCX: caa11c2bced69b00
RDX: 0000000000000001 RSI: ffffffff8a0b1620 RDI: ffffffff8a59a240
RBP: ffffffff8be07ef8 R08: dffffc0000000000 R09: ffffed101720765a
R10: ffffed101720765a R11: 1ffff11017207659 R12: ffffffff8d698f28
R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff17d7878
 default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
 cpuidle_idle_call kernel/sched/idle.c:194 [inline]
 do_idle+0x21b/0x5b0 kernel/sched/idle.c:306
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:403
 start_kernel+0x486/0x530 init/main.c:1140
 secondary_startup_64_no_verify+0xb1/0xbb
 </TASK>
----------------
Code disassembly (best guess):
   0:	bf 48 89 df e8       	mov    $0xe8df8948,%edi
   5:	46 f5                	rex.RX cmc
   7:	09 f8                	or     %edi,%eax
   9:	eb b5                	jmp    0xffffffc0
   b:	e8 3f b0 f6 ff       	call   0xfff6b04f
  10:	00 00                	add    %al,(%rax)
  12:	cc                   	int3
  13:	cc                   	int3
  14:	00 00                	add    %al,(%rax)
  16:	cc                   	int3
  17:	cc                   	int3
  18:	00 00                	add    %al,(%rax)
  1a:	cc                   	int3
  1b:	cc                   	int3
  1c:	00 00                	add    %al,(%rax)
  1e:	cc                   	int3
  1f:	66 90                	xchg   %ax,%ax
  21:	0f 00 2d f7 83 53 00 	verw   0x5383f7(%rip)        # 0x53841f
  28:	fb                   	sti
  29:	f4                   	hlt
* 2a:	c3                   	ret <-- trapping instruction
  2b:	0f 1f 40 00          	nopl   0x0(%rax)
  2f:	41 57                	push   %r15
  31:	41 56                	push   %r14
  33:	53                   	push   %rbx
  34:	49 be 00 00 00 00 00 	movabs $0xdffffc0000000000,%r14
  3b:	fc ff df
  3e:	65                   	gs
  3f:	48                   	rex.W

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/10 06:25 linux-5.15.y de9476bb4f1b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2025/09/10 06:17 linux-5.15.y de9476bb4f1b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2025/08/12 14:10 linux-5.15.y c79648372d02 c06e8995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2025/07/02 22:11 linux-5.15.y 3dea0e7f549e bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
* Struck through repros no longer work on HEAD.