From patchwork Tue Aug 23 05:41:46 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: 12951750 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 95550C32774 for ; Tue, 23 Aug 2022 05:57:06 +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=6lvzabLyVFlsraTigrhnhhdyWFXC/Mcnqyhuft5t9ek=; b=gu6iktwBgxI26h Tt3I/ez8LE7bbySXMocC8e7soIMkuYynODJldcJ6aocYEkcGwvtAe9LDRdpa+D1ZGHR+i3AwJk/Dc oS/FQX1NwsI9w5PNJ6ZllE+deZcv53Asbeqik6JBbMJsqwvJ2WrzJZdAM/DOIe22kLMeYB3kzmVk6 FwEl7AUkLbeEN6r7wbrsbNoV9On7RvTPOI5zoQepYVxfj+GVN6Lde0+q7i0B6MyhQOw8hHZHgONXO rOENvXo42cQBnm44CuCnucc1Qj9So086KuYDRj5xazVP4kTuc/BbH/fpZ/24OkQB+QM8UX8kOQbi3 qh/ZsnhVGA8wvqnAG0Vw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oQMsg-002bzO-6C; Tue, 23 Aug 2022 05:55:19 +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 1oQMq6-002aNz-RW; Tue, 23 Aug 2022 05:52:40 +0000 X-UUID: c6288bae65be40d1ab149d7a180285b0-20220822 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=fu5ShSj1KW2IHzRk7qvbTGi9RMnjs01NSv05MXGrhK8=; b=aOu84Ko+ZmisIdEvkENOEF+f2BgvowOG+nJ+fse8IxsZYPcUGq7b1E/Dh49mraBmkJ3ER0Fx99rz+FDumtpgsj738Tie50tgfNU9eSb2lYexOHkWc68/Ud16Z0y+0uPUngRfXzBX4T3Qheq2H4jVVQ6P9sZW8iMKjQu2uEAvNXY=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.10,REQID:1a6bdb07-63ae-436d-b38b-a2a3ad5253a0,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:cfd47fc9-6b09-4f60-bf82-12f039f5d530,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:1,File:nil ,Bulk:nil,QS:nil,BEC:nil,COL:0 X-UUID: c6288bae65be40d1ab149d7a180285b0-20220822 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 1335329578; Mon, 22 Aug 2022 22:52:34 -0700 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) 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 13:41:57 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Tue, 23 Aug 2022 13:41:57 +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 , Jing-Ting Wu , , , , Subject: [PATCH 1/1] cgroup: Fix race condition at rebind_subsystems() Date: Tue, 23 Aug 2022 13:41:46 +0800 Message-ID: <20220823054148.29346-1-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_225238_934730_0ACB05A1 X-CRM114-Status: UNSURE ( 8.28 ) 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. Reported-by: Jing-Ting Wu Suggested-by: Michal Koutný Signed-off-by: Jing-Ting Wu Tested-by: Jing-Ting Wu Link: https://lore.kernel.org/linux-arm-kernel/d8f0bc5e2fb6ed259f9334c83279b4c011283c41.camel@mediatek.com/T/ Acked-by: Mukesh Ojha --- 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); }