linux-kernel - Re: [PATCH 00/10] use folio in ksm

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Date: Wed, 5 Jun 2024 11:46:24 +0800
From: Alex Shi <seakeel@...il.com>
To: David Hildenbrand <david@...hat.com>, alexs@...nel.org,
 Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, izik.eidus@...ellosystems.com,
 willy@...radead.org, aarcange@...hat.com, chrisw@...s-sol.org,
 hughd@...gle.com
Subject: Re: [PATCH 00/10] use folio in ksm



On 6/4/24 9:28 PM, David Hildenbrand wrote:
> On 04.06.24 06:24, alexs@...nel.org wrote:
>> From: "Alex Shi (tencent)" <alexs@...nel.org>
>>
>> This is the 2nd part to use folio in ksm, it saves 82kbytes in ksm.o and
>> passed all ksm testcases in kselftest.
>>
>> KSM still split same folios to single page if they are good to be KSM,
>> but will skip the rest subpage checking if a folio couldn't suit for
>> ksm.
>>
>> Alex Shi (tencent) (10):
>>    mm/ksm: reduce the flush action for ksm merging page
>>    mm/ksm: skip subpages of compound pages
>>    mm/ksm: use folio in try_to_merge_one_page
>>    mm/ksm: add identical_folio func
>>    mm/ksm: use folio in stable_tree_search
>>    mm/ksm: remove page_stable_node
>>    mm/ksm: use folio in unstable_tree_search_insert
>>    mm/ksm: use folio in try_to_merge_xx serie funcs
>>    mm/ksm: calc_checksum for folio
>>    m/ksm: use folio in ksm scan path
> 
> I skimmed over most patches, but I'm afraid you introduce quite some subtle problems.
> 
> Part of the rework should not be do convert things to folios that really operate on pages (of possibly large folios).
> 
> We really have to be careful about pages vs. folios before we have KSM folios. Only then, we know that we have small folios only.
> 

Thanks a lot for your reviewing and comments. Let's if we'd do it better with your comments! :)

Thanks
Alex