linux-kernel - Re: [PATCH v2 2/2] memblock: exclude MEMBLOCK

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Message-ID: <5fb2f209-e048-f6f9-4ad3-96645d23fce8@linaro.org>
Date:   Thu, 21 Oct 2021 11:03:48 +0300
From:   Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To:     Mike Rapoport <rppt@...nel.org>, linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Qian Cai <quic_qiancai@...cinc.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] memblock: exclude MEMBLOCK_NOMAP regions from
 kmemleak

Hi Mike,

On 10/21/21 10:09 AM, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@...ux.ibm.com>
> 
> Vladimir Zapolskiy reports:
> 
> commit a7259df76702 ("memblock: make memblock_find_in_range method private")
> invokes a kernel panic while running kmemleak on OF platforms with nomaped
> regions:
> 
>    Unable to handle kernel paging request at virtual address fff000021e00000
>    [...]
>      scan_block+0x64/0x170
>      scan_gray_list+0xe8/0x17c
>      kmemleak_scan+0x270/0x514
>      kmemleak_write+0x34c/0x4ac
> 
> The memory allocated from memblock is registered with kmemleak, but if it
> is marked MEMBLOCK_NOMAP it won't have linear map entries so an attempt to
> scan such areas will fault.
> 
> Ideally, memblock_mark_nomap() would inform kmemleak to ignore
> MEMBLOCK_NOMAP memory, but it can be called before kmemleak interfaces
> operating on physical addresses can use __va() conversion.
> 
> Make sure that functions that mark allocated memory as MEMBLOCK_NOMAP take
> care of informing kmemleak to ignore such memory.
> 
> Link: https://lore.kernel.org/all/8ade5174-b143-d621-8c8e-dc6a1898c6fb@linaro.org
> Link: https://lore.kernel.org/all/c30ff0a2-d196-c50d-22f0-bd50696b1205@quicinc.com
> Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private")
> Reported-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>

this change variant also solves the reported problem, thank you.

Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>

--
Best wishes,
Vladimir