2022-03-02 10:03:40

by Muchun Song

Subject: [PATCH v4 1/6] mm: rmap: fix cache flush on THP pages

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 <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
---
mm/rmap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index fc46a3d7b704..723682ddb9e8 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -970,7 +970,8 @@ static bool page_mkclean_one(struct folio *folio, struct vm_area_struct *vma,
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
continue;

- flush_cache_page(vma, address, folio_pfn(folio));
+ 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

2022-03-11 05:53:07

by Dan Williams

Subject: Re: [PATCH v4 1/6] mm: rmap: fix cache flush on THP pages

On Wed, Mar 2, 2022 at 12:29 AM Muchun Song <[email protected]> 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 <[email protected]>
> Reviewed-by: Yang Shi <[email protected]>

Reviewed-by: Dan Williams <[email protected]>