From patchwork Wed Jun 28 06:07:23 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sahitya Tummala X-Patchwork-Id: 9813535 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5E300603D7 for ; Wed, 28 Jun 2017 06:07:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 513D62841E for ; Wed, 28 Jun 2017 06:07:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4584E28462; Wed, 28 Jun 2017 06:07:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C01B72841E for ; Wed, 28 Jun 2017 06:07:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbdF1GHl (ORCPT ); Wed, 28 Jun 2017 02:07:41 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:34216 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751678AbdF1GHk (ORCPT ); Wed, 28 Jun 2017 02:07:40 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 7DCB960867; Wed, 28 Jun 2017 06:07:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1498630059; bh=yD3G/WEuVHoFDQ5xn2DgulwKiUYldX6PNbXnXYvSvFg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IG4fNgg0gL6EYF+yzOdtQWgMIdmvJskGOSAIXdkgj1eE2FnMEt/YLN2SjSgi5LQ03 cTLJKLTHwaKfVLs9Oq/6/VtpMeHC3x7qrWE6GuWE7EpTTxXfxWxEhOxVeNdecktjYJ N07sRrDgnZDg5nhTtHZMpmmIfvvt1m786pmzkSw4= Received: from codeaurora.org (blr-c-bdr-fw-01_globalnat_allzones-outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: stummala@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 16C9A60867; Wed, 28 Jun 2017 06:07:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1498630058; bh=yD3G/WEuVHoFDQ5xn2DgulwKiUYldX6PNbXnXYvSvFg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IATuzsEHHRj2fACVjCnZGEQy/UQWUFQDLVlaMTwoRZnneeNc+vi5wvhiMJZOePMrj PL7oW/SVdBRDvSr7Z6GLv3iVB1ZQaIJTurjYh4Nf1N6BiLFG8BkIo9OztgkQH5kYqQ SbguUghuHuJtOVHQQPAI3nVR/quFX7L/uBJ+JFdM= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 16C9A60867 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=stummala@codeaurora.org From: Sahitya Tummala To: Alexander Polakov , Andrew Morton , Vladimir Davydov , Jan Kara , viro@zeniv.linux.org.uk, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: Sahitya Tummala Subject: [PATCH v3 1/2] mm/list_lru.c: fix list_lru_count_node() to be race free Date: Wed, 28 Jun 2017 11:37:23 +0530 Message-Id: <1498630044-26724-1-git-send-email-stummala@codeaurora.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <20170622174929.GB3273@esperanza> References: <20170622174929.GB3273@esperanza> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP list_lru_count_node() iterates over all memcgs to get the total number of entries on the node but it can race with memcg_drain_all_list_lrus(), which migrates the entries from a dead cgroup to another. This can return incorrect number of entries from list_lru_count_node(). Fix this by keeping track of entries per node and simply return it in list_lru_count_node(). Signed-off-by: Sahitya Tummala --- include/linux/list_lru.h | 1 + mm/list_lru.c | 14 ++++++-------- 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h index cb0ba9f..eff61bc 100644 --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -44,6 +44,7 @@ struct list_lru_node { /* for cgroup aware lrus points to per cgroup lists, otherwise NULL */ struct list_lru_memcg *memcg_lrus; #endif + long nr_count; } ____cacheline_aligned_in_smp; struct list_lru { diff --git a/mm/list_lru.c b/mm/list_lru.c index 234676e..d417b9f 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -117,6 +117,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item) l = list_lru_from_kmem(nlru, item); list_add_tail(item, &l->list); l->nr_items++; + nlru->nr_count++; spin_unlock(&nlru->lock); return true; } @@ -136,6 +137,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item) l = list_lru_from_kmem(nlru, item); list_del_init(item); l->nr_items--; + nlru->nr_count--; spin_unlock(&nlru->lock); return true; } @@ -183,15 +185,10 @@ unsigned long list_lru_count_one(struct list_lru *lru, unsigned long list_lru_count_node(struct list_lru *lru, int nid) { - long count = 0; - int memcg_idx; + struct list_lru_node *nlru; - count += __list_lru_count_one(lru, nid, -1); - if (list_lru_memcg_aware(lru)) { - for_each_memcg_cache_index(memcg_idx) - count += __list_lru_count_one(lru, nid, memcg_idx); - } - return count; + nlru = &lru->node[nid]; + return nlru->nr_count; } EXPORT_SYMBOL_GPL(list_lru_count_node); @@ -226,6 +223,7 @@ unsigned long list_lru_count_node(struct list_lru *lru, int nid) assert_spin_locked(&nlru->lock); case LRU_REMOVED: isolated++; + nlru->nr_count--; /* * If the lru lock has been dropped, our list * traversal is now invalid and so we have to