The patch titled
Subject: dax: fix cache flush on PMD-mapped pages
has been added to the -mm tree. Its filename is
dax-fix-cache-flush-on-pmd-mapped-pages.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/dax-fix-cache-flush-on-pmd-mapped-pages.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/dax-fix-cache-flush-on-pmd-mapped-pages.patch
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------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: dax: fix cache flush on PMD-mapped 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. 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")
Link: https://lkml.kernel.org/r/20220318074529.5261-3-songmuchun@xxxxxxxxxxxxx
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>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Cc: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/dax.c~dax-fix-cache-flush-on-pmd-mapped-pages
+++ a/fs/dax.c
@@ -845,7 +845,8 @@ static void dax_entry_mkclean(struct add
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);
pmd = pmdp_invalidate(vma, address, pmdp);
pmd = pmd_wrprotect(pmd);
pmd = pmd_mkclean(pmd);
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-kfence-fix-objcgs-vector-allocation.patch
mm-rmap-fix-cache-flush-on-thp-pages.patch
dax-fix-cache-flush-on-pmd-mapped-pages.patch
mm-rmap-introduce-pfn_mkclean_range-to-cleans-ptes.patch
mm-pvmw-add-support-for-walking-devmap-pages.patch
dax-fix-missing-writeprotect-the-pte-entry.patch
dax-fix-missing-writeprotect-the-pte-entry-v6.patch
mm-simplify-follow_invalidate_pte.patch
