linux-kernel - Re: [PATCH 5/6] mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype

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Date:   Wed, 1 Sep 2021 16:02:39 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     David Hildenbrand <david@...hat.com>
CC:     <akpm@...ux-foundation.org>, <vbabka@...e.cz>,
        <sfr@...b.auug.org.au>, <peterz@...radead.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [PATCH 5/6] mm/page_alloc.c: avoid accessing uninitialized pcp
 page migratetype

On 2021/8/31 22:23, David Hildenbrand wrote:
> On 31.08.21 15:43, Mel Gorman wrote:
>> On Mon, Aug 30, 2021 at 10:10:50PM +0800, Miaohe Lin wrote:
>>> If it's not prepared to free unref page, the pcp page migratetype is
>>> unset. Thus We will get rubbish from get_pcppage_migratetype() and
>>> might list_del &page->lru again after it's already deleted from the
>>> list leading to grumble about data corruption.
>>>
>>> Fixes: 3dcbe270d8ec ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
>>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
>>
>> Acked-by: Mel Gorman <mgorman@...hsingularity.net>
>>
>> This fix is fairly important. Take this patch out and send it on its own
>> so it gets picked up relatively quickly. It does not belong in a series
>> that is mostly cosmetic cleanups.
> 
> I think the commit id is wrong. Shouldn't that be
> 
> df1acc856923 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
> 
> ?
> 

Many thanks for pointing this out.

I used to save the git log in a file to make life easier. But it seems this leads
to the old commit id above.

commit 3dcbe270d8ec57e534f5c605279cdc3ceb1f044a
Author: Mel Gorman <mgorman@...hsingularity.net>
Date:   Fri Jun 4 14:20:03 2021 +1000

    mm/page_alloc: avoid conflating IRQs disabled with zone->lock

git name-rev 3dcbe270d8ec
3dcbe270d8ec tags/next-20210604~2^2~196

vs

commit df1acc856923c0a65c28b588585449106c316b71
Author: Mel Gorman <mgorman@...hsingularity.net>
Date:   Mon Jun 28 19:42:00 2021 -0700

    mm/page_alloc: avoid conflating IRQs disabled with zone->lock

git name-rev df1acc856923
df1acc856923 tags/next-20210630~2^2~278

Their contents are same but with different commit id. The previous one
could have been git-rebased.