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From: Zicheng Qu <quzicheng@huawei.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: <mingo@redhat.com>, <juri.lelli@redhat.com>,
	<vincent.guittot@linaro.org>, <dietmar.eggemann@arm.com>,
	<rostedt@goodmis.org>, <bsegall@google.com>, <mgorman@suse.de>,
	<vschneid@redhat.com>, <linux-kernel@vger.kernel.org>,
	<tanghui20@huawei.com>, <zhangqiao22@huawei.com>,
	<judy.chenhui@huawei.com>
Subject: Re: [PATCH] sched/fair: Fix overflow in vruntime_eligible() causing NULL return
Date: Thu, 10 Jul 2025 10:01:15 +0800	[thread overview]
Message-ID: <d8588f5d-bccc-4791-9d44-bd3e383d21b9@huawei.com> (raw)
In-Reply-To: <20250709115317.GK1613200@noisy.programming.kicks-ass.net>

Hi,

Based on LTS 6.6. I also looked at the code logic around 
vruntime_eligible() in the mainline. It seems that if 
vruntime_eligible() consistently returned false, this could lead to null 
pointer dereferences.

I'm wondering if it's feasible to adjust the handling of integer 
overflows within vruntime_eligible() the way shown in my patch, or if 
there's a specific design rationale behind directly comparing integers 
that are susceptible to overflow in the current implementation?

Thanks

On 7/9/2025 7:53 PM, Peter Zijlstra wrote:
> On Wed, Jul 09, 2025 at 09:38:29AM +0000, Zicheng Qu wrote:
>
>> The best approach should be to dig deep into why overflow occurs, which
>> attributes lead to the overflow, whether it is normal, and how to avoid
>> it.
> What kernel version are you seeing this on?
>

  reply	other threads:[~2025-07-10  2:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-09  9:38 Zicheng Qu
2025-07-09 11:53 ` Peter Zijlstra
2025-07-10  2:01   ` Zicheng Qu [this message]
2025-07-10 11:13     ` Peter Zijlstra
2025-08-07  3:06 ` Fang Xiang
2025-08-08  9:21 quzicheng
2026-01-06 11:34 Fang Xiang

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