From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758755AbcC3HKr (ORCPT ); Wed, 30 Mar 2016 03:10:47 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:44650 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758582AbcC3HKi (ORCPT ); Wed, 30 Mar 2016 03:10:38 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: minchan@kernel.org X-Original-SENDERIP: 10.177.223.161 X-Original-MAILFROM: minchan@kernel.org From: Minchan Kim To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, jlayton@poochiereds.net, bfields@fieldses.org, Vlastimil Babka , Joonsoo Kim , koct9i@gmail.com, aquini@redhat.com, virtualization@lists.linux-foundation.org, Mel Gorman , Hugh Dickins , Sergey Senozhatsky , Rik van Riel , rknize@motorola.com, Gioh Kim , Sangseok Lee , Chan Gyun Jeong , Al Viro , YiPing Xu , Minchan Kim , Naoya Horiguchi Subject: [PATCH v3 01/16] mm: use put_page to free page instead of putback_lru_page Date: Wed, 30 Mar 2016 16:12:00 +0900 Message-Id: <1459321935-3655-2-git-send-email-minchan@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1459321935-3655-1-git-send-email-minchan@kernel.org> References: <1459321935-3655-1-git-send-email-minchan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Procedure of page migration is as follows: First of all, it should isolate a page from LRU and try to migrate the page. If it is successful, it releases the page for freeing. Otherwise, it should put the page back to LRU list. For LRU pages, we have used putback_lru_page for both freeing and putback to LRU list. It's okay because put_page is aware of LRU list so if it releases last refcount of the page, it removes the page from LRU list. However, It makes unnecessary operations (e.g., lru_cache_add, pagevec and flags operations. It would be not significant but no worth to do) and harder to support new non-lru page migration because put_page isn't aware of non-lru page's data structure. To solve the problem, we can add new hook in put_page with PageMovable flags check but it can increase overhead in hot path and needs new locking scheme to stabilize the flag check with put_page. So, this patch cleans it up to divide two semantic(ie, put and putback). If migration is successful, use put_page instead of putback_lru_page and use putback_lru_page only on failure. That makes code more readable and doesn't add overhead in put_page. Comment from Vlastimil "Yeah, and compaction (perhaps also other migration users) has to drain the lru pvec... Getting rid of this stuff is worth even by itself." Cc: Mel Gorman Cc: Hugh Dickins Cc: Naoya Horiguchi Acked-by: Vlastimil Babka Signed-off-by: Minchan Kim --- mm/migrate.c | 50 +++++++++++++++++++++++++++++++------------------- 1 file changed, 31 insertions(+), 19 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 6c822a7b27e0..53529c805752 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -913,6 +913,14 @@ static int __unmap_and_move(struct page *page, struct page *newpage, put_anon_vma(anon_vma); unlock_page(page); out: + /* If migration is successful, move newpage to right list */ + if (rc == MIGRATEPAGE_SUCCESS) { + if (unlikely(__is_movable_balloon_page(newpage))) + put_page(newpage); + else + putback_lru_page(newpage); + } + return rc; } @@ -946,6 +954,12 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page, if (page_count(page) == 1) { /* page was freed from under us. So we are done. */ + ClearPageActive(page); + ClearPageUnevictable(page); + if (put_new_page) + put_new_page(newpage, private); + else + put_page(newpage); goto out; } @@ -958,10 +972,8 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page, } rc = __unmap_and_move(page, newpage, force, mode); - if (rc == MIGRATEPAGE_SUCCESS) { - put_new_page = NULL; + if (rc == MIGRATEPAGE_SUCCESS) set_page_owner_migrate_reason(newpage, reason); - } out: if (rc != -EAGAIN) { @@ -974,28 +986,28 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page, list_del(&page->lru); dec_zone_page_state(page, NR_ISOLATED_ANON + page_is_file_cache(page)); - /* Soft-offlined page shouldn't go through lru cache list */ + } + + /* + * If migration is successful, drop the reference grabbed during + * isolation. Otherwise, restore the page to LRU list unless we + * want to retry. + */ + if (rc == MIGRATEPAGE_SUCCESS) { + put_page(page); if (reason == MR_MEMORY_FAILURE) { - put_page(page); if (!test_set_page_hwpoison(page)) num_poisoned_pages_inc(); - } else + } + } else { + if (rc != -EAGAIN) putback_lru_page(page); + if (put_new_page) + put_new_page(newpage, private); + else + put_page(newpage); } - /* - * If migration was not successful and there's a freeing callback, use - * it. Otherwise, putback_lru_page() will drop the reference grabbed - * during isolation. - */ - if (put_new_page) - put_new_page(newpage, private); - else if (unlikely(__is_movable_balloon_page(newpage))) { - /* drop our reference, page already in the balloon */ - put_page(newpage); - } else - putback_lru_page(newpage); - if (result) { if (rc) *result = rc; -- 1.9.1