linux-kernel - Re: [PATCH 2/3] proc: kpagecount: use snapshot

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Message-ID: <3c0eb35d-86e2-45ea-b933-32989c28963a@redhat.com>
Date: Wed, 2 Jul 2025 13:38:45 -0400
From: Luiz Capitulino <luizcap@...hat.com>
To: Shivank Garg <shivankg@....com>, david@...hat.com, willy@...radead.org
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, lcapitulino@...il.com
Subject: Re: [PATCH 2/3] proc: kpagecount: use snapshot_page()

On 2025-07-02 02:25, Shivank Garg wrote:
> 
> 
> On 6/26/2025 11:46 PM, Luiz Capitulino wrote:
>> Currently, the call to folio_precise_page_mapcount() from kpage_read()
>> can race with a folio split. When the race happens we trigger a
>> VM_BUG_ON_FOLIO() in folio_entire_mapcount() (see splat below).
>>
>> This commit fixes this race by using snapshot_page() so that we
>> retreive the folio mapcount using a folio snapshot.
> 
> s/retreive/retrieve/
> checkpatch.pl would have flagged this.

Thanks for pointing this out. I do run checkpatch.pl before sending patches,
I don't know how I missed this.

> 
> Rest looks good to me.
> 
> Thanks,
> Shivank
>