linux-kernel - Re: [PATCH] kmemleak: fix check for softirq context

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Message-Id: <20190517143746.2157a759f65b4cbc73321124@linux-foundation.org>
Date:   Fri, 17 May 2019 14:37:46 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Dmitry Vyukov <dvyukov@...il.com>
Cc:     catalin.marinas@....com, Dmitry Vyukov <dvyukov@...gle.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kmemleak: fix check for softirq context

On Fri, 17 May 2019 19:15:07 +0200 Dmitry Vyukov <dvyukov@...il.com> wrote:

> From: Dmitry Vyukov <dvyukov@...gle.com>
> 
> in_softirq() is a wrong predicate to check if we are in a softirq context.
> It also returns true if we have BH disabled, so objects are falsely
> stamped with "softirq" comm. The correct predicate is in_serving_softirq().
>
> ...
> 
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -588,7 +588,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
>  	if (in_irq()) {
>  		object->pid = 0;
>  		strncpy(object->comm, "hardirq", sizeof(object->comm));
> -	} else if (in_softirq()) {
> +	} else if (in_serving_softirq()) {
>  		object->pid = 0;
>  		strncpy(object->comm, "softirq", sizeof(object->comm));
>  	} else {

What are the user-visible runtime effects of this change?