linux-kernel - Re: [PATCH 0/2] don't use mapcount() to check large folio sharing

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Message-ID: <29cd58c4-08d3-c03c-7232-15f85878934d@intel.com>
Date:   Wed, 2 Aug 2023 20:39:21 +0800
From:   "Yin, Fengwei" <fengwei.yin@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Yin Fengwei <fengwei.yin@...el.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <stable@...r.kernel.org>, <willy@...radead.org>,
        <vishal.moola@...il.com>, <wangkefeng.wang@...wei.com>,
        <minchan@...nel.org>, <yuzhao@...gle.com>, <david@...hat.com>,
        <ryan.roberts@....com>, <shy828301@...il.com>
Subject: Re: [PATCH 0/2] don't use mapcount() to check large folio sharing

Hi Andrew,

On 7/29/2023 1:24 AM, Andrew Morton wrote:
> On Sat, 29 Jul 2023 00:13:54 +0800 Yin Fengwei <fengwei.yin@...el.com> wrote:
> 
>> In madvise_cold_or_pageout_pte_range() and madvise_free_pte_range(),
>> folio_mapcount() is used to check whether the folio is shared. But it's
>> not correct as folio_mapcount() returns total mapcount of large folio.
>>
>> Use folio_estimated_sharers() here as the estimated number is enough.
> 
> What are the user-visible runtime effects of these changes?
> 
> (and please try to avoid using the same Subject: for different patches)
> 

Can you hold on these patches to mm-unstable? I think we need to wait for
David's work on folio_maybe_mapped_shared() and redo the fix base on that.
Thanks and sorry for the noise.


Regards
Yin, Fengwei