[syzbot] [kernel?] INFO: rcu detected stall in kthread_worker_fn (2)

From: syzbot
Date: Thu Mar 13 2025 - 05:29:38 EST

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Hello,

syzbot found the following issue on:

HEAD commit: b7c90e3e717a Merge tag 'x86-urgent-2025-03-08' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=110bf3a8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=523d3ff8e053340a
dashboard link: https://syzkaller.appspot.com/bug?extid=2ea3f3959d6a151d0865
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d81fa0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f57e200ffcd6/disk-b7c90e3e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c6ab88f8b93e/vmlinux-b7c90e3e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/02dd888a913e/bzImage-b7c90e3e.xz

The issue was bisected to:

commit 5a781ccbd19e4664babcbe4b4ead7aa2b9283d22
Author: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
Date: Sat Sep 29 00:59:43 2018 +0000

tc: Add support for configuring the taprio scheduler

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17000654580000
console output: https://syzkaller.appspot.com/x/log.txt?x=10800654580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ea3f3959d6a151d0865@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 5a781ccbd19e ("tc: Add support for configuring the taprio scheduler")

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 ticks this GP) idle=eaac/1/0x4000000000000000 softirq=14535/14535 fqs=0
rcu: (detected by 0, t=10506 jiffies, g=9453, q=274 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 20 Comm: rcu_exp_gp_kthr Not tainted 6.14.0-rc5-syzkaller-00234-gb7c90e3e717a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:kasan_mem_to_shadow include/linux/kasan.h:64 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x37/0x290 mm/kasan/generic.c:189
Code: 01 48 85 f6 0f 84 a0 01 00 00 4c 8d 04 37 49 39 f8 0f 82 56 02 00 00 48 89 fd 48 c1 ed 2f 81 fd fe ff 01 00 0f 86 43 02 00 00 <48> 89 fb 48 c1 eb 03 49 ba 00 00 00 00 00 fc ff df 4e 8d 1c 13 49
RSP: 0018:ffffc90000a28ad0 EFLAGS: 00000002
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff819cd274
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff903bcd70
RBP: 000000000001ffff R08: ffffffff903bcd78 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff89fcfe20 R12: 1ffff92000145168
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff88801d6ce4d8
FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa29cf13f98 CR3: 0000000034486000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<IRQ>
instrument_atomic_read include/linux/instrumented.h:68 [inline]
_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
cpumask_test_cpu include/linux/cpumask.h:570 [inline]
cpu_online include/linux/cpumask.h:1116 [inline]
trace_lock_acquire include/trace/events/lock.h:24 [inline]
lock_acquire+0xd4/0x550 kernel/locking/lockdep.c:5822
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
advance_sched+0xab/0xca0 net/sched/sch_taprio.c:924
__run_hrtimer kernel/time/hrtimer.c:1801 [inline]
__hrtimer_run_queues+0x59b/0xd30 kernel/time/hrtimer.c:1865
hrtimer_interrupt+0x403/0xa40 kernel/time/hrtimer.c:1927
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
__sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:finish_task_switch+0x1ea/0x870 kernel/sched/core.c:5252
Code: c9 50 e8 69 2d 0c 00 48 83 c4 08 4c 89 f7 e8 fd 39 00 00 0f 1f 44 00 00 4c 89 f7 e8 e0 0f 73 0a e8 7b 07 39 00 fb 48 8b 5d c0 <48> 8d bb 08 16 00 00 48 89 f8 48 c1 e8 03 49 be 00 00 00 00 00 fc
RSP: 0018:ffffc90000197ae8 EFLAGS: 00000282
RAX: 834d0290e8134100 RBX: ffff88801d6cda00 RCX: ffffffff9a61b903
RDX: dffffc0000000000 RSI: ffffffff8c2ab2a0 RDI: ffffffff8c802ae0
RBP: ffffc90000197b30 R08: ffffffff903bcd77 R09: 1ffffffff20779ae
R10: dffffc0000000000 R11: fffffbfff20779af R12: 1ffff110170e7ebe
R13: dffffc0000000000 R14: ffff8880b873e7c0 R15: ffff8880b873f5f0
context_switch kernel/sched/core.c:5381 [inline]
__schedule+0x18c4/0x4c40 kernel/sched/core.c:6765
__schedule_loop kernel/sched/core.c:6842 [inline]
schedule+0x14b/0x320 kernel/sched/core.c:6857
kthread_worker_fn+0x491/0xb70 kernel/kthread.c:1017
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10505 jiffies! g9453 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: Possible timer handling issue on cpu=1 timer-softirq=2864
rcu: rcu_preempt kthread starved for 10506 jiffies! g9453 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:26104 pid:18 tgid:18 ppid:2 task_flags:0x208040 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5378 [inline]
__schedule+0x18bc/0x4c40 kernel/sched/core.c:6765
__schedule_loop kernel/sched/core.c:6842 [inline]
schedule+0x14b/0x320 kernel/sched/core.c:6857
schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2024
rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2226
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

---
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Next message: Barry Song: "Re: [PATCH 0/2] Improve Zram by separating compression context from kswapd"
Previous message: Philipp Stanner: "Re: [PATCH v2 1/2] drm/sched: Fix outdated comments referencing thread"
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