From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751255Ab1CAFAS (ORCPT ); Tue, 1 Mar 2011 00:00:18 -0500 Received: from mail-yx0-f174.google.com ([209.85.213.174]:62386 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750710Ab1CAFAQ (ORCPT ); Tue, 1 Mar 2011 00:00:16 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer; b=TT/2f2H4vIFFWTyC7Ze4EB4Mj8ZRpZHdOWFQELVE9ypreJY9fbmfBN8V8QVDZw5+Hl 7Jj8eIKnn2sZM9QakF5ncFkVhFM6VNZE4V/8zQJ9pLZUYj46q2Sm/DKCI9eHhdj2p+6m XDUZHn9vL0ULxTCixdixRAkX2WxqYdSvF/PGw= From: Minchan Kim To: Andrew Morton Cc: linux-mm , LKML , Johannes Weiner , Daisuke Nishimura , KAMEZAWA Hiroyuki , Minchan Kim , Balbir Singh Subject: [PATCH v2] memcg: clean up migration Date: Tue, 1 Mar 2011 13:59:06 +0900 Message-Id: <1298955546-2450-1-git-send-email-minchan.kim@gmail.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch cleans up unncessary BUG_ON check and confusing charge variable. That's because memcg charge/uncharge could be handled by mem_cgroup_[prepare/end] migration itself so charge local variable in unmap_and_move lost the role since we introduced [01b1ae6 memcg: simple migration handling] And mem_cgroup_prepare_migration return 0 if only it is successful. Otherwise, it jumps to unlock label to clean up so BUG_ON(charge) isn't meaningless. Reviewed-by: Johannes Weiner Acked-by: Daisuke Nishimura Acked-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Signed-off-by: Minchan Kim * Change from v1 - add acked-by/reviewed-by - change typo --- mm/memcontrol.c | 1 + mm/migrate.c | 14 ++++---------- 2 files changed, 5 insertions(+), 10 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2fc97fc..6832926 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2872,6 +2872,7 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry, /* * Before starting migration, account PAGE_SIZE to mem_cgroup that the old * page belongs to. + * Return 0 if charge is successful. Otherwise return -errno. */ int mem_cgroup_prepare_migration(struct page *page, struct page *newpage, struct mem_cgroup **ptr, gfp_t gfp_mask) diff --git a/mm/migrate.c b/mm/migrate.c index eb083a6..737c2e5 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -622,7 +622,6 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, int *result = NULL; struct page *newpage = get_new_page(page, private, &result); int remap_swapcache = 1; - int charge = 0; struct mem_cgroup *mem; struct anon_vma *anon_vma = NULL; @@ -637,9 +636,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, if (unlikely(split_huge_page(page))) goto move_newpage; - /* prepare cgroup just returns 0 or -ENOMEM */ rc = -EAGAIN; - if (!trylock_page(page)) { if (!force) goto move_newpage; @@ -678,13 +675,11 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, } /* charge against new page */ - charge = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL); - if (charge == -ENOMEM) { - rc = -ENOMEM; + rc = mem_cgroup_prepare_migration(page, newpage, &mem, GFP_KERNEL); + if (rc) goto unlock; - } - BUG_ON(charge); + rc = -EAGAIN; if (PageWriteback(page)) { if (!force || !sync) goto uncharge; @@ -767,8 +762,7 @@ skip_unmap: drop_anon_vma(anon_vma); uncharge: - if (!charge) - mem_cgroup_end_migration(mem, page, newpage, rc == 0); + mem_cgroup_end_migration(mem, page, newpage, rc == 0); unlock: unlock_page(page); -- 1.7.1