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

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Message-Id: <20230728102405.7b456eb87fb46042fbce5e4b@linux-foundation.org>
Date:   Fri, 28 Jul 2023 10:24:05 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     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

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)