Re: [PATCH v5 2/6] dax: fix cache flush on PMD-mapped pages

[Christoph Hellwig]

On Fri, Mar 18, 2022 at 03:45:25PM +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.  This is just a
> documentation issue with the respect to properly documenting the expected
> usage of cache flushing before modifying the pmd.  However, in practice
> this is not a problem due to the fact that DAX is not available on
> architectures with virtually indexed caches per:
> 
>   commit d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
> 
> Fixes: f729c8c9b24f ("dax: wrprotect pmd_t in dax_mapping_entry_mkclean")
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Looks good:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>