linux-kernel - Re: [RESEND PATCH v7 01/10] mm: Allow deferred splitting of arbitrary anon large folios

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Message-Id: <20231127082711.12885-1-v-songbaohua@oppo.com>
Date:   Mon, 27 Nov 2023 21:27:11 +1300
From:   Barry Song <21cnbao@...il.com>
To:     ryan.roberts@....com
Cc:     akpm@...ux-foundation.org, anshuman.khandual@....com,
        catalin.marinas@....com, david@...hat.com, fengwei.yin@...el.com,
        hughd@...gle.com, itaru.kitayama@...il.com, jhubbard@...dia.com,
        kirill.shutemov@...ux.intel.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, mcgrof@...nel.org, rientjes@...gle.com,
        shy828301@...il.com, vbabka@...e.cz, wangkefeng.wang@...wei.com,
        willy@...radead.org, ying.huang@...el.com, yuzhao@...gle.com,
        ziy@...dia.com, Barry Song <v-songbaohua@...o.com>
Subject: Re: [RESEND PATCH v7 01/10] mm: Allow deferred splitting of arbitrary anon large folios

> In preparation for the introduction of anonymous small-sized THP, we
> would like to be able to split them when they have unmapped subpages, in
> order to free those unused pages under memory pressure. So remove the
> artificial requirement that the large folio needed to be at least
> PMD-sized.
> 
> Reviewed-by: Yu Zhao <yuzhao@...gle.com>
> Reviewed-by: Yin Fengwei <fengwei.yin@...el.com>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Reviewed-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---

Reviewed-by: Barry Song <v-songbaohua@...o.com>

>  mm/rmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 7a27a2b41802..49e4d86a4f70 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1488,11 +1488,11 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
>  		__lruvec_stat_mod_folio(folio, idx, -nr);
> 
>  		/*
> -		 * Queue anon THP for deferred split if at least one
> +		 * Queue anon large folio for deferred split if at least one
>  		 * page of the folio is unmapped and at least one page
>  		 * is still mapped.
>  		 */
> -		if (folio_test_pmd_mappable(folio) && folio_test_anon(folio))
> +		if (folio_test_large(folio) && folio_test_anon(folio))
>  			if (!compound || nr < nr_pmdmapped)
>  				deferred_split_folio(folio);
>  	}
> --
> 2.25.1

Thanks
Barry