+ dax-fix-cache-flush-on-pmd-mapped-pages.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

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@bytedance.com>
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/20220403053957.10770-3-songmuchun@bytedance.com
Fixes: f729c8c9b24f ("dax: wrprotect pmd_t in dax_mapping_entry_mkclean")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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@bytedance.com are

mm-hugetlb_vmemmap-introduce-arch_want_hugetlb_page_free_vmemmap.patch
arm64-mm-hugetlb-enable-hugetlb_page_free_vmemmap-for-arm64.patch
mm-hugetlb_vmemmap-cleanup-hugetlb_vmemmap-related-functions.patch
mm-hugetlb_vmemmap-cleanup-hugetlb_free_vmemmap_enabled.patch
mm-hugetlb_vmemmap-cleanup-config_hugetlb_page_free_vmemmap.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
mm-simplify-follow_invalidate_pte.patch