From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Subject: mm: thp: relocate flush_cache_range() in migrate_misplaced_transhuge_page() There should be no cache left by the time we overwrite the old transhuge pmd with the new one. It's already too late to flush through the virtual address because we already copied the page data to the new physical address. So flush the cache before the data copy. Also delete the "end" variable to shutoff a "unused variable" warning on x86 where flush_cache_range() is a noop. Link: http://lkml.kernel.org/r/20181015202311.7209-1-aarcange@xxxxxxxxxx Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Aaron Tomlin <atomlin@xxxxxxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/migrate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/migrate.c~mm-thp-relocate-flush_cache_range-in-migrate_misplaced_transhuge_page +++ a/mm/migrate.c @@ -1976,7 +1976,6 @@ int migrate_misplaced_transhuge_page(str struct page *new_page = NULL; int page_lru = page_is_file_cache(page); unsigned long start = address & HPAGE_PMD_MASK; - unsigned long end = start + HPAGE_PMD_SIZE; new_page = alloc_pages_node(node, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), @@ -1999,6 +1998,8 @@ int migrate_misplaced_transhuge_page(str /* anon mapping, we can simply copy page->mapping to the new page: */ new_page->mapping = page->mapping; new_page->index = page->index; + /* flush the cache before copying using the kernel virtual address */ + flush_cache_range(vma, start, start + HPAGE_PMD_SIZE); migrate_page_copy(new_page, page); WARN_ON(PageLRU(new_page)); @@ -2036,7 +2037,6 @@ int migrate_misplaced_transhuge_page(str * new page and page_add_new_anon_rmap guarantee the copy is * visible before the pagetable update. */ - flush_cache_range(vma, start, end); page_add_anon_rmap(new_page, vma, start, true); /* * At this point the pmd is numa/protnone (i.e. non present) and the TLB _
