linux-kernel - Re: [PATCH] mm: kmemleak: Ignore kmemleak scanning on CMA regions

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Date:   Sun, 28 Nov 2021 09:50:53 +0800
From:   Calvin Zhang <calvinzhang.cool@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Subject: Re: [PATCH] mm: kmemleak: Ignore kmemleak scanning on CMA regions

On Sat, Nov 27, 2021 at 04:07:18PM -0800, Andrew Morton wrote:
>On Fri, 26 Nov 2021 10:47:11 +0800 Calvin Zhang <calvinzhang.cool@...il.com> wrote:
>
>> Just like this:
>> commit 620951e27457 ("mm/cma: make kmemleak ignore CMA regions").
>> 
>> Add kmemleak_ignore_phys() for CMA created from of reserved node.
>
>Could we please have a full, standalone changelog for this patch?

Yes, I will add.

>
>The 620951e27457 changelog says "Without this, the kernel crashes...". 
>Does your patch also fix a crash?  If so under what circumstances and
>should we backport this fix into -stable kernels?

No crash occurred. 620951e27457 avoids crashes caused by accessing
highmem and it was fixed later. Now kmemleak_alloc_phys() and
kmemleak_ignore_phys() skip highmem. This patch is based on the
point that CMA regions don't contain pointers to other kmemleak
objects, and ignores CMA regions from reserved memory as what
620951e27457 did.

--
Thanks
Calvin