linux-kernel - Re: [PATCH] sched,psi: fix the 'int' underflow for psi

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Date:   Thu, 15 Apr 2021 20:25:32 +0530
From:   Charan Teja Kalla <charante@...eaurora.org>
To:     Johannes Weiner <hannes@...xchg.org>
Cc:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched,psi: fix the 'int' underflow for psi

Thanks Johannes!!

On 4/15/2021 8:12 PM, Johannes Weiner wrote:
> Makes sense, it's more graceful in the event of a bug.
> 
> But what motivates this change? Is it something you hit recently with
> an upstream kernel and we should investigate?

We specifically didn't hit the issue around this change. Identified this
while doing code walk through.

> 
> There is already a branch on the tasks to signal the bug. How about:
> 
> 		if (groupc->tasksk[t]) {
> 			groupc->tasks[t]--;
> 		} else if (!psi_bug) {
> 			printk_deferred(...
> 			psi_bug = 1;
> 		}

Looks cleaner. Will raise V2 with this.
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