From patchwork Tue Aug 23 05:09:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jing-Ting Wu X-Patchwork-Id: 12951708 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 80F23C25B08 for ; Tue, 23 Aug 2022 05:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:CC :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=NZJASYCntu3TgeHY4UoguEGvOyKU0yxgjkp0kuVjBuQ=; b=lloVRlS60u+jMt 1Y9xJbvxsgu6oxC1gH6b8Aon0KGZDMoRjXL0Ms77pEl3Zcv9XLEpzpfBFi1XuQgRrZQ3JcAPyroJB C48w40GAB6Y4UWwn++i+kbQPJZ968nO/xKc8hcLr4oefZdAP16/7zT2ANvjXW2/Dd+ybZWZBLFzf3 vmDG4OqVKNKdebeJw/hZ65B2nFPERLqAro/kjH+bml+VOq7fDmoDwuN1bQXD7WGkI9TOVABbmsbg8 aecZflPJQkMffZZscrFJc8El6d05avb1hc7PR6vOrTbwEZLsicvi6q7B+zsWnJfmtRaCr34Yza3Ug BnwdGvrzPlspWKWZ0mxw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQMMK-002LJ2-DB; Tue, 23 Aug 2022 05:21:52 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQMMG-002LGT-5R; Tue, 23 Aug 2022 05:21:49 +0000 X-UUID: ab327334466c4c589a3ba40d593de05f-20220822 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=ijokMmJKsT0+CBQ8Gdmv6lUHjb9/6ryw7rMwmSGnkVw=; b=GByrc0r3KGPbaCEiHMyIryxylUl/rH/AF3p/EIBetbHVoteuc28GINy4DQQZhC3G2vtFfGpjEJ+1SbHZR1GNitPZLcOFZVjjvOA0V8hjwNaJS4C1FSSXg/ilHhI1NBN5o83jhC6g0jQfHM9dOU72A7+kJD5dJRLpoxhkAXvsodU=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.10,REQID:844bb3b4-141a-4271-bbf2-d3440e37f657,OB:0,L OB:0,IP:0,URL:0,TC:0,Content:-5,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release _Ham,ACTION:release,TS:-5 X-CID-META: VersionHash:84eae18,CLOUDID:18ac4fcf-20bd-4e5e-ace8-00692b7ab380,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:0,File:nil ,Bulk:nil,QS:nil,BEC:nil,COL:0 X-UUID: ab327334466c4c589a3ba40d593de05f-20220822 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 607362142; Mon, 22 Aug 2022 22:21:43 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.186) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Tue, 23 Aug 2022 13:11:06 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Tue, 23 Aug 2022 13:11:06 +0800 From: Jing-Ting Wu To: =?utf-8?q?Michal_Koutn=C3=BD?= , Tejun Heo , Zefan Li , Johannes Weiner , Matthias Brugger CC: , , , , Jing-Ting Wu , , , , Subject: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Date: Tue, 23 Aug 2022 13:09:41 +0800 Message-ID: <20220823050943.28619-1-Jing-Ting.Wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220822_222148_230223_3CDDA137 X-CRM114-Status: UNSURE ( 8.49 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Root cause: The rebind_subsystems() is no lock held when move css object from A list to B list,then let B's head be treated as css node at list_for_each_entry_rcu(). Solution: Add grace period before invalidating the removed rstat_css_node. Suggested-by: Michal Koutný Signed-off-by: Jing-Ting Wu --- kernel/cgroup/cgroup.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index ffaccd6373f1..0d0c959966ed 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1820,6 +1820,7 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) if (ss->css_rstat_flush) { list_del_rcu(&css->rstat_css_node); + synchronize_rcu(); list_add_rcu(&css->rstat_css_node, &dcgrp->rstat_css_list); }