From: Muchun Song songmuchun@bytedance.com
commit 2771739a7162782c0aa6424b2e3dd874e884a15d upstream.
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.
But there is no issues on arm64 and powerpc since they already considers the compound page cache flushing in their icache flush function. 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/20220210123058.79206-3-songmuchun@bytedance.com Fixes: 290408d4a250 ("hugetlb: hugepage migration core") Signed-off-by: Muchun Song songmuchun@bytedance.com Reviewed-by: Zi Yan ziy@nvidia.com Cc: Axel Rasmussen axelrasmussen@google.com Cc: David Rientjes rientjes@google.com Cc: Fam Zheng fam.zheng@bytedance.com Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Lars Persson lars.persson@axis.com Cc: Mike Kravetz mike.kravetz@oracle.com Cc: Peter Xu peterx@redhat.com Cc: Xiongchun Duan duanxiongchun@bytedance.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/migrate.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/mm/migrate.c +++ b/mm/migrate.c @@ -994,9 +994,12 @@ 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;