linux-kernel - Re: [PATCH v2 1/6] mm: rmap: fix cache flush on THP pages

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Date:   Thu, 3 Feb 2022 11:16:38 +0100
From:   Jan Kara <jack@...e.cz>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     dan.j.williams@...el.com, willy@...radead.org, jack@...e.cz,
        viro@...iv.linux.org.uk, akpm@...ux-foundation.org,
        apopple@...dia.com, shy828301@...il.com, rcampbell@...dia.com,
        hughd@...gle.com, xiyuyang19@...an.edu.cn,
        kirill.shutemov@...ux.intel.com, zwisler@...nel.org,
        hch@...radead.org, linux-fsdevel@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, duanxiongchun@...edance.com
Subject: Re: [PATCH v2 1/6] mm: rmap: fix cache flush on THP pages

On Wed 02-02-22 22:33:02, Muchun Song wrote:
> The flush_cache_page() only remove a PAGE_SIZE sized range from the cache.
> However, it does not cover the full pages in a THP except a head page.
> Replace it with flush_cache_range() to fix this issue. At least, no
> problems were found due to this. Maybe because the architectures that
> have virtual indexed caches is less.
> 
> Fixes: f27176cfc363 ("mm: convert page_mkclean_one() to use page_vma_mapped_walk()")
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> Reviewed-by: Yang Shi <shy828301@...il.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  mm/rmap.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index b0fd9dc19eba..0ba12dc9fae3 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -974,7 +974,8 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
>  			if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
>  				continue;
>  
> -			flush_cache_page(vma, address, page_to_pfn(page));
> +			flush_cache_range(vma, address,
> +					  address + HPAGE_PMD_SIZE);
>  			entry = pmdp_invalidate(vma, address, pmd);
>  			entry = pmd_wrprotect(entry);
>  			entry = pmd_mkclean(entry);
> -- 
> 2.11.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR