linux-kernel - Re: [PATCH] mm: kmemleak: alloc gray object for reserved region with direct map.

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Message-ID: <YaA56JVYPfzCsawG@debian>
Date:   Fri, 26 Nov 2021 09:35:36 +0800
From:   Calvin Zhang <calvinzhang.cool@...il.com>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH] mm: kmemleak: alloc gray object for reserved region with
 direct map.

On Thu, Nov 25, 2021 at 05:17:53PM +0000, Catalin Marinas wrote:
>On Tue, Nov 23, 2021 at 05:06:41PM +0800, Calvin Zhang wrote:
>> Reserved regions with direct mapping may contain references to other
>> regions. CMA region with fixed location is reserved without creating
>> kmemleak_object for it.
>> 
>> So add them as gray kmemleak objects.
>
>Do you get any kmemleak false positives without this patch? It would be
>good to include them in the commit message.

Sorry, no. I thought it was possible before I saw this commit:
620951e27457 ("mm/cma: make kmemleak ignore CMA regions"). 

>
>Without seeing a false positive caused by this, I'm not convinced it is
>the right approach. You mentioned CMA but telling kmemleak about the
>whole CMA region is a pretty big hammer. I'd rather add individual
>kmemleak_alloc_*() calls in cma_alloc().

Yeah, I agree.

--
Calvin