linux-kernel - Re: [PATCH] mm/kmemleak: Move up cond_resched() call in page scanning loop

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Message-ID: <ZOtKq99/aZCNkav6@arm.com>
Date:   Sun, 27 Aug 2023 16:07:55 +0300
From:   Catalin Marinas <catalin.marinas@....com>
To:     Waiman Long <longman@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Yisheng Xie <xieyisheng1@...wei.com>
Subject: Re: [PATCH] mm/kmemleak: Move up cond_resched() call in page
 scanning loop

On Fri, Aug 25, 2023 at 12:49:47PM -0400, Waiman Long wrote:
> Commit bde5f6bc68db ("kmemleak: add scheduling point to kmemleak_scan()")
> added a cond_resched() call to the struct page scanning loop to prevent
> soft lockup from happening. However, soft lockup can still happen in
> that loop in some corner cases when the pages that satisfy the "!(pfn &
> 63)" check are skipped for some reasons.
> 
> Fix this corner case by moving up the cond_resched() check so that it
> will be called every 64 pages unconditionally.
> 
> Fixes: bde5f6bc68db ("kmemleak: add scheduling point to kmemleak_scan()")
> Signed-off-by: Waiman Long <longman@...hat.com>

Acked-by: Catalin Marinas <catalin.marinas@....com>