linux-kernel - Re: [PATCH] mm/kmemleak: Prevent soft lockup in kmemleak

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Message-Id: <20221020175823.d7aa5cfeefd8673429f42081@linux-foundation.org>
Date:   Thu, 20 Oct 2022 17:58:23 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Waiman Long <longman@...hat.com>
Cc:     Catalin Marinas <catalin.marinas@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: Re: [PATCH] mm/kmemleak: Prevent soft lockup in kmemleak_scan()'s
 object iteration loops

On Thu, 20 Oct 2022 13:56:19 -0400 Waiman Long <longman@...hat.com> wrote:

> Commit 6edda04ccc7c ("mm/kmemleak: prevent soft lockup in first object
> iteration loop of kmemleak_scan()") adds cond_resched() in the first
> object iteration loop of kmemleak_scan(). However, it turns that the
> 2nd objection iteration loop can still cause soft lockup to happen in
> some cases. So add a cond_resched() call in the 2nd and 3rd loops as
> well to prevent that and for completeness.
> 

Seems reasonable, although not an object of beauty.

We didn't include a Fixes: or cc:stable in 6edda04ccc7c, even though it
addresses softlockups.  I think I'll add a cc:stable to this, with a
Fixes:6edda04ccc7c.  So any kenrel which included 6edda04ccc7c will
hopefully add this as well.