From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37130C43381 for ; Wed, 27 Feb 2019 17:21:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F16A321850 for ; Wed, 27 Feb 2019 17:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729310AbfB0RVS (ORCPT ); Wed, 27 Feb 2019 12:21:18 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:37348 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726223AbfB0RVR (ORCPT ); Wed, 27 Feb 2019 12:21:17 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5A1D31688; Wed, 27 Feb 2019 09:21:17 -0800 (PST) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4B0543F703; Wed, 27 Feb 2019 09:21:16 -0800 (PST) Date: Wed, 27 Feb 2019 17:21:13 +0000 From: Catalin Marinas To: Qian Cai Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/page_ext: fix an imbalance with kmemleak Message-ID: <20190227172113.GE125513@arrakis.emea.arm.com> References: <20190227171556.75444-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190227171556.75444-1-cai@lca.pw> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 27, 2019 at 12:15:56PM -0500, Qian Cai wrote: > After offlined a memory block, kmemleak scan will trigger a crash, as it > encounters a page ext address that has already been freed during memory > offlining. At the beginning in alloc_page_ext(), it calls > kmemleak_alloc(), but it does not call kmemleak_free() in > __free_page_ext(). [...] > diff --git a/mm/page_ext.c b/mm/page_ext.c > index 8c78b8d45117..b68f2a58ea3b 100644 > --- a/mm/page_ext.c > +++ b/mm/page_ext.c > @@ -288,6 +288,7 @@ static void __free_page_ext(unsigned long pfn) > base = get_entry(ms->page_ext, pfn); > free_page_ext(base); > ms->page_ext = NULL; > + kmemleak_free(base); > } The kmemleak_free() call should be placed before free_page_ext() to avoid a small window where the address has been freed but kmemleak not informed. -- Catalin