Re: [PATCH 2/5] dax: fix cache flush on PMD-mapped pages

[Christoph Hellwig]

On Fri, Jan 21, 2022 at 03:55:12PM +0800, 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.
> 
> Fixes: f729c8c9b24f ("dax: wrprotect pmd_t in dax_mapping_entry_mkclean")
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
>  fs/dax.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 88be1c02a151..2955ec65eb65 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -857,7 +857,7 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
>  			if (!pmd_dirty(*pmdp) && !pmd_write(*pmdp))
>  				goto unlock_pmd;
>  
> -			flush_cache_page(vma, address, pfn);
> +			flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);

Same comment as for the previous one.