From: syzbot <syzbot+e0fa723f5960605c7ddb@syzkaller.appspotmail.com>
To: davem@davemloft.net, edumazet@google.com, horms@kernel.org,
jhs@mojatatu.com, jiri@resnulli.us, kuba@kernel.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
pabeni@redhat.com, syzkaller-bugs@googlegroups.com,
vinicius.gomes@intel.com
Subject: [syzbot] [net?] INFO: rcu detected stall in advance_sched (2)
Date: Sun, 27 Sep 2026 02:01:27 -0700 [thread overview]
Message-ID: <6ab8db67.dc2998a4.2261f5.0064.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: aa98230e410f Merge tag 'vfs-7.3-rc5.fixes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a3e2c9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=718e346eb0b8f38
dashboard link: https://syzkaller.appspot.com/bug?extid=e0fa723f5960605c7ddb
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d8db131abdba/disk-aa98230e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/58014231ef21/vmlinux-aa98230e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/97cab136e4af/bzImage-aa98230e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e0fa723f5960605c7ddb@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P29
rcu: (detected by 1, t=10592 jiffies, g=56017, q=13328 ncpus=2)
task:ktimers/1 state:R running task stack:24168 pid:29 tgid:29 ppid:2 task_flags:0x4208040 flags:0x00080010
Call Trace:
<IRQ>
sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8250
rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline]
print_other_cpu_stall+0xfbf/0x1350 kernel/rcu/tree_stall.h:683
check_cpu_stall kernel/rcu/tree_stall.h:860 [inline]
rcu_pending kernel/rcu/tree.c:3744 [inline]
rcu_sched_clock_irq+0x9fe/0x10e0 kernel/rcu/tree.c:2749
update_process_times+0x234/0x2d0 kernel/time/timer.c:2475
tick_sched_handle kernel/time/tick-sched.c:296 [inline]
tick_nohz_handler+0x38f/0x6b0 kernel/time/tick-sched.c:317
__run_hrtimer kernel/time/hrtimer.c:2074 [inline]
__hrtimer_run_queues+0x3a0/0xaf0 kernel/time/hrtimer.c:2131
hrtimer_interrupt+0x4c2/0xa80 kernel/time/hrtimer.c:2250
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 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:lock_is_held_type+0x106/0x150 kernel/locking/lockdep.c:6021
Code: 1b 00 00 b8 ff ff ff ff 65 0f c1 05 c4 bd 4d 07 83 f8 01 75 25 9c 58 a9 00 02 00 00 75 39 41 f7 c4 00 02 00 00 74 01 fb 89 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 4b d1 03 00 cc 90 0f 0b 90 48 c7
RSP: 0018:ffffc90000a3fab8 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8dae029b RDI: ffffffff8bcc4a80
RBP: 00000000ffffffff R08: 0000000000000100 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1f64530 R12: 0000000000000246
R13: ffff88801d2c3e80 R14: ffff888060f6e400 R15: 0000000000000004
lock_is_held include/linux/lockdep.h:249 [inline]
advance_sched+0xea/0xc90 net/sched/sch_taprio.c:933
__run_hrtimer kernel/time/hrtimer.c:2074 [inline]
__hrtimer_run_queues+0x3eb/0xaf0 kernel/time/hrtimer.c:2131
hrtimer_run_softirq+0x1e1/0x2e0 kernel/time/hrtimer.c:2148
handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
run_ktimerd+0x6a/0x100 kernel/softirq.c:1174
smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
kthread+0x38b/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10596 jiffies! g56017 f0x0 RCU_GP_WAIT_FQS(5) ->state=I
rcu: Possible timer handling issue on cpu=1 timer-softirq=32843
rcu: rcu_preempt kthread starved for 10597 jiffies! g56017 f0x0 RCU_GP_WAIT_FQS(5) ->state=I ->cpu=1
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:I stack:27784 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5533 [inline]
__schedule+0x16d9/0x5700 kernel/sched/core.c:7284
__schedule_loop kernel/sched/core.c:7361 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7376
schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122
rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330
kthread+0x38b/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:lock_is_held_type+0x106/0x150 kernel/locking/lockdep.c:6021
Code: 1b 00 00 b8 ff ff ff ff 65 0f c1 05 c4 bd 4d 07 83 f8 01 75 25 9c 58 a9 00 02 00 00 75 39 41 f7 c4 00 02 00 00 74 01 fb 89 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 4b d1 03 00 cc 90 0f 0b 90 48 c7
RSP: 0018:ffffc90000a3fab8 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000046
RDX: 0000000000000000 RSI: ffffffff8dae029b RDI: ffffffff8bcc4a80
RBP: 00000000ffffffff R08: 0000000000000100 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1f64530 R12: 0000000000000246
R13: ffff88801d2c3e80 R14: ffff888060f6e400 R15: 0000000000000004
FS: 0000000000000000(0000) GS:ffff888125cc4000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3101f81e80 CR3: 000000000dfb0000 CR4: 00000000003526f0
Call Trace:
<TASK>
lock_is_held include/linux/lockdep.h:249 [inline]
advance_sched+0xea/0xc90 net/sched/sch_taprio.c:933
__run_hrtimer kernel/time/hrtimer.c:2074 [inline]
__hrtimer_run_queues+0x3eb/0xaf0 kernel/time/hrtimer.c:2131
hrtimer_run_softirq+0x1e1/0x2e0 kernel/time/hrtimer.c:2148
handle_softirqs+0x1da/0x6d0 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
run_ktimerd+0x6a/0x100 kernel/softirq.c:1174
smpboot_thread_fn+0x565/0xa70 kernel/smpboot.c:160
kthread+0x38b/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
---
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reply other threads:[~2026-09-27 9:01 UTC|newest]
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