mm: thp: relocate flush_cache_range() in migrate_misplaced_transhuge_page() (7eef5f97) · Commits · 戴 / test

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@redhat.com Signed-off-by:

Andrea Arcangeli <aarcange@redhat.com> Acked-by:

Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1976,7 +1976,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
		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(struct mm_struct *mm,
		/* 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(struct mm_struct *mm,
		* 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

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