syzbot


WARNING in rcu_check_gp_start_stall (4)

Status: upstream: reported on 2026/02/20 21:56
Reported-by: syzbot+e952109dd720d190f944@syzkaller.appspotmail.com
First crash: 111d, last: 15h36m
Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in rcu_check_gp_start_stall net prio:low -1 C done error 2931 5d00h 2666d 0/29 upstream: reported C repro on 2019/02/22 17:10
linux-5.15 WARNING in rcu_check_gp_start_stall (3) -1 6 217d 344d 0/3 auto-obsoleted due to no activity on 2026/02/15 02:49
linux-6.6 WARNING in rcu_check_gp_start_stall origin:lts-only -1 C done 137 1h43m 360d 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 634d 778d 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 917d 917d 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 31 15d 998d 0/3 upstream: reported C repro on 2023/09/17 20:24

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5344 at kernel/rcu/tree_stall.h:937 rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:929
Modules linked in:
CPU: 1 PID: 5344 Comm: kworker/1:14 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events nsim_dev_trap_report_work
RIP: 0010:rcu_check_gp_start_stall+0x2dc/0x460 kernel/rcu/tree_stall.h:937
Code: ff ff ff 48 c7 c7 20 3c 32 96 be 04 00 00 00 e8 ca ef 58 00 48 89 df b8 01 00 00 00 87 05 ec c7 cc 14 85 c0 0f 85 19 ff ff ff <0f> 0b 48 81 ff c0 37 32 8c 74 47 48 c7 c0 84 3a 8a 8d 48 c1 e8 03
RSP: 0018:ffffc90000dd0c78 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffffffff8c3237c0 RCX: ffffffff81657426
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff8c3237c0
RBP: ffffc90000dd0ed0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff2c64784 R12: 0000000000002904
R13: ffff8880b913b258 R14: 0000000000000a02 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3a659b CR3: 0000000020569000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_core+0x62b/0x1670 kernel/rcu/tree.c:2758
 handle_softirqs+0x339/0x830 kernel/softirq.c:576
 do_softirq+0x142/0x210 kernel/softirq.c:477
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x180/0x1c0 kernel/softirq.c:401
 spin_unlock_bh include/linux/spinlock.h:409 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:736 [inline]
 nsim_dev_trap_report_work+0x7cf/0xb50 drivers/net/netdevsim/dev.c:762
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/12 00:33 linux-5.15.y dc027a595035 d93a6ab6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2026/05/23 03:44 linux-5.15.y 93741761e5e3 c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2026/03/06 15:49 linux-5.15.y 91d48252ad4b 41d8037d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in rcu_check_gp_start_stall
2026/02/20 21:55 linux-5.15.y 3330a8d33e08 6e7b5511 .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.