linux-kernel - Re: [PATCH v1 06/10] mm: Allow deferred splitting of arbitrary large anon folios

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Date:   Wed, 28 Jun 2023 10:43:05 +0800
From:   Yin Fengwei <fengwei.yin@...el.com>
To:     Ryan Roberts <ryan.roberts@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        David Hildenbrand <david@...hat.com>,
        Yu Zhao <yuzhao@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-alpha@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-ia64@...r.kernel.org>, <linux-m68k@...ts.linux-m68k.org>,
        <linux-s390@...r.kernel.org>
Subject: Re: [PATCH v1 06/10] mm: Allow deferred splitting of arbitrary large
 anon folios



On 6/27/23 01:14, Ryan Roberts wrote:
> With the introduction of large folios for anonymous memory, 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.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
Reviewed-by: Yin Fengwei <fengwei.yin@...el.com>


Regards
Yin, Fengwei

> ---
>  mm/rmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index ac1d93d43f2b..3d11c5fb6090 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1567,7 +1567,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
>  		 * 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);
>  	}