The patch titled
Subject: mm: fix missing cache flush for all tail pages of compound page
has been added to the -mm tree. Its filename is
mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
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------------------------------------------------------
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Subject: mm: fix missing cache flush for all tail pages of compound page
The D-cache maintenance inside move_to_new_page() only consider one page,
there is still D-cache maintenance issue for tail pages of compound page
(e.g. THP or HugeTLB). THP migration is only enabled on x86_64, ARM64
and powerpc, while powerpc and arm64 need to maintain the consistency
between I-Cache and D-Cache, which depends on flush_dcache_page() to
maintain the consistency between I-Cache and D-Cache. In theory, the
issue can be found on arm64 and powerpc. HugeTLB migration is enabled on
arm, arm64, mips, parisc, powerpc, riscv, s390 and sh, while arm has
handled the compound page cache flush in flush_dcache_page(), but most
others do not. In theory, the issue exists on many architectures. Fix
this by not using flush_dcache_folio() since it is not backportable.
Link: https://lkml.kernel.org/r/20220131160254.43211-3-songmuchun@xxxxxxxxxxxxx
Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
Fixes: 290408d4a250 ("hugetlb: hugepage migration core")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lars Persson <lars.persson@xxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mina Almasry <almasrymina@xxxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/mm/migrate.c~mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page
+++ a/mm/migrate.c
@@ -916,9 +916,12 @@ static int move_to_new_page(struct page
if (!PageMappingFlags(page))
page->mapping = NULL;
- if (likely(!is_zone_device_page(newpage)))
- flush_dcache_page(newpage);
+ if (likely(!is_zone_device_page(newpage))) {
+ int i, nr = compound_nr(newpage);
+ for (i = 0; i < nr; i++)
+ flush_dcache_page(newpage + i);
+ }
}
out:
return rc;
_
Patches currently in -mm which might be from songmuchun@xxxxxxxxxxxxx are
mm-thp-fix-wrong-cache-flush-in-remove_migration_pmd.patch
mm-fix-missing-cache-flush-for-all-tail-pages-of-compound-page.patch
mm-hugetlb-fix-missing-cache-flush-in-copy_huge_page_from_user.patch
mm-hugetlb-fix-missing-cache-flush-in-hugetlb_mcopy_atomic_pte.patch
mm-replace-multiple-dcache-flush-with-flush_dcache_folio.patch
mm-hugetlb-free-the-2nd-vmemmap-page-associated-with-each-hugetlb-page.patch
mm-hugetlb-replace-hugetlb_free_vmemmap_enabled-with-a-static_key.patch
mm-sparsemem-use-page-table-lock-to-protect-kernel-pmd-operations.patch
selftests-vm-add-a-hugetlb-test-case.patch
mm-sparsemem-move-vmemmap-related-to-hugetlb-to-config_hugetlb_page_free_vmemmap.patch
