This is a note to let you know that I've just added the patch titled
dax: fix cache flush on PMD-mapped pages
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dax-fix-cache-flush-on-pmd-mapped-pages.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 86f4afadb70c0f6f5741a54265103f0cb6fc5ee2
Author: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Date: Thu Apr 28 23:16:09 2022 -0700
dax: fix cache flush on PMD-mapped pages
[ Upstream commit e583b5c472bd23d450e06f148dc1f37be74f7666 ]
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/20220403053957.10770-3-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>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/dax.c b/fs/dax.c
index 67a08a32fccb..a372304c9695 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -845,7 +845,8 @@ 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);
pmd = pmdp_invalidate(vma, address, pmdp);
pmd = pmd_wrprotect(pmd);
pmd = pmd_mkclean(pmd);
