linux-kernel - "INFO: rcu_tasks_trace detected stalls on tasks in kernel/sched/core.c" in Linux kernel version 6.13.0-rc2

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Message-ID: <CAKHoSAvxELqPbBhuAT3i1ce_OOh-c0_eHnU_5RX9q8eK1oEEdg@mail.gmail.com>
Date: Fri, 3 Jan 2025 16:11:18 +0800
From: cheung wall <zzqq0103.hey@...il.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
	Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, 
	Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Valentin Schneider <vschneid@...hat.com>, linux-kernel@...r.kernel.org
Subject: "INFO: rcu_tasks_trace detected stalls on tasks in
 kernel/sched/core.c" in Linux kernel version 6.13.0-rc2

Hello,

I am writing to report a potential vulnerability identified in the
Linux Kernel version 6.13.0-rc2. This issue was discovered using our
custom vulnerability discovery tool.

HEAD commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4 (tag: v6.13-rc2)

Affected File: kernel/sched/core.c

File: kernel/sched/core.c

Detailed Call Stack:

------------[ cut here begin]------------

INFO: rcu_tasks_trace detected stalls on tasks
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5369 [inline]
__schedule+0xcf2/0x23f0 kernel/sched/core.c:6756
__schedule_loop kernel/sched/core.c:6833 [inline]
schedule+0x79/0x290 kernel/sched/core.c:6848
do_nanosleep+0x1a7/0x430 kernel/time/hrtimer.c:2079
hrtimer_nanosleep+0x12a/0x410 kernel/time/hrtimer.c:2126
common_nsleep+0x94/0xc0 kernel/time/posix-timers.c:1356
__do_sys_clock_nanosleep kernel/time/posix-timers.c:1402 [inline]
__se_sys_clock_nanosleep kernel/time/posix-timers.c:1379 [inline]
__x64_sys_clock_nanosleep+0x2e3/0x400 kernel/time/posix-timers.c:1379
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xa6/0x1a0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f029f3dbdaa
RSP: 002b:00007fffd2a6b500 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f029f3dbdaa
RDX: 00007fffd2a6b590 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007fffd2a6b61c R08: 0000000000019800 R09: 00007f02a00d3000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffd2a6b590
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005
</TASK>

------------[ cut here end]------------

Root Cause:

The system crash was triggered by a malfunction in the Linux kernel’s
scheduler, specifically within the context_switch, __schedule,
__schedule_loop, and schedule functions located in
kernel/sched/core.c. These scheduler functions failed to properly
manage task states, causing critical tasks like syz-executor.7 and
systemd-udevd to become stuck in a running state while attempting to
execute sleep operations. Concurrent filesystem issues, including
unexpected loop device capacity changes and unrecognized mount
parameters, likely exacerbated the problem by imposing additional
stress on the scheduler. This combination led to prolonged
Read-Copy-Update (RCU) stalls, preventing the system from efficiently
handling task scheduling and ultimately resulting in the crash.

Thank you for your time and attention.

Best regards

Wall