Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760033AbcDEUoW (ORCPT ); Tue, 5 Apr 2016 16:44:22 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:34928 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759941AbcDEUoV (ORCPT ); Tue, 5 Apr 2016 16:44:21 -0400 Date: Tue, 5 Apr 2016 13:44:16 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Andrew Morton cc: "Kirill A. Shutemov" , Andrea Arcangeli , Andres Lagar-Cavilla , Yang Shi , Ning Qu , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 03/10] mm: use __SetPageSwapBacked and dont ClearPageSwapBacked In-Reply-To: Message-ID: References: User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3879 Lines: 113 v3.16 commit 07a427884348 ("mm: shmem: avoid atomic operation during shmem_getpage_gfp") rightly replaced one instance of SetPageSwapBacked by __SetPageSwapBacked, pointing out that the newly allocated page is not yet visible to other users (except speculative get_page_unless_zero- ers, who may not update page flags before their further checks). That was part of a series in which Mel was focused on tmpfs profiles: but almost all SetPageSwapBacked uses can be so optimized, with the same justification. Remove ClearPageSwapBacked from __read_swap_cache_async() error path: it's not an error to free a page with PG_swapbacked set. Follow a convention of __SetPageLocked, __SetPageSwapBacked instead of doing it differently in different places; but that's for tidiness - if the ordering actually mattered, we should not be using the __variants. There's probably scope for further __SetPageFlags in other places, but SwapBacked is the one I'm interested in at the moment. Signed-off-by: Hugh Dickins --- Sorry, Mel did give Reviewed-by: Mel Gorman a year ago, but the kernel has moved on since then, so it feels slightly ruder to carry that forward without asking, than to ask again after all this time not submitting what he approved. mm/migrate.c | 6 +++--- mm/rmap.c | 2 +- mm/shmem.c | 4 ++-- mm/swap_state.c | 3 +-- 4 files changed, 7 insertions(+), 8 deletions(-) --- a/mm/migrate.c +++ b/mm/migrate.c @@ -332,7 +332,7 @@ int migrate_page_move_mapping(struct add newpage->index = page->index; newpage->mapping = page->mapping; if (PageSwapBacked(page)) - SetPageSwapBacked(newpage); + __SetPageSwapBacked(newpage); return MIGRATEPAGE_SUCCESS; } @@ -378,7 +378,7 @@ int migrate_page_move_mapping(struct add newpage->index = page->index; newpage->mapping = page->mapping; if (PageSwapBacked(page)) - SetPageSwapBacked(newpage); + __SetPageSwapBacked(newpage); get_page(newpage); /* add cache reference */ if (PageSwapCache(page)) { @@ -1785,7 +1785,7 @@ int migrate_misplaced_transhuge_page(str /* Prepare a page as a migration target */ __SetPageLocked(new_page); - SetPageSwapBacked(new_page); + __SetPageSwapBacked(new_page); /* anon mapping, we can simply copy page->mapping to the new page: */ new_page->mapping = page->mapping; --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1249,7 +1249,7 @@ void page_add_new_anon_rmap(struct page int nr = compound ? hpage_nr_pages(page) : 1; VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); - SetPageSwapBacked(page); + __SetPageSwapBacked(page); if (compound) { VM_BUG_ON_PAGE(!PageTransHuge(page), page); /* increment count (starts at -1) */ --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1085,8 +1085,8 @@ static int shmem_replace_page(struct pag flush_dcache_page(newpage); __SetPageLocked(newpage); + __SetPageSwapBacked(newpage); SetPageUptodate(newpage); - SetPageSwapBacked(newpage); set_page_private(newpage, swap_index); SetPageSwapCache(newpage); @@ -1276,8 +1276,8 @@ repeat: goto decused; } - __SetPageSwapBacked(page); __SetPageLocked(page); + __SetPageSwapBacked(page); if (sgp == SGP_WRITE) __SetPageReferenced(page); --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -358,7 +358,7 @@ struct page *__read_swap_cache_async(swp /* May fail (-ENOMEM) if radix-tree node allocation failed. */ __SetPageLocked(new_page); - SetPageSwapBacked(new_page); + __SetPageSwapBacked(new_page); err = __add_to_swap_cache(new_page, entry); if (likely(!err)) { radix_tree_preload_end(); @@ -370,7 +370,6 @@ struct page *__read_swap_cache_async(swp return new_page; } radix_tree_preload_end(); - ClearPageSwapBacked(new_page); __ClearPageLocked(new_page); /* * add_to_swap_cache() doesn't return -EEXIST, so we can safely