From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752215AbdJFOCe (ORCPT ); Fri, 6 Oct 2017 10:02:34 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:34514 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750950AbdJFOCd (ORCPT ); Fri, 6 Oct 2017 10:02:33 -0400 Date: Fri, 6 Oct 2017 15:02:29 +0100 From: Catalin Marinas To: Konstantin Khlebnikov Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, Andy Lutomirski Subject: Re: [PATCH] kmemleak: clear stale pointers from task stacks Message-ID: <20171006140229.p5be6n6peafqasgl@armageddon.cambridge.arm.com> References: <150728990124.744199.8403409836394318684.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <150728990124.744199.8403409836394318684.stgit@buzz> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 06, 2017 at 02:38:21PM +0300, Konstantin Khlebnikov wrote: > Kmemleak considers any pointers as task stacks as references. ^^ on > This patch clears newly allocated and reused vmap stacks. > > Signed-off-by: Konstantin Khlebnikov > --- > include/linux/thread_info.h | 2 +- > kernel/fork.c | 4 ++++ > 2 files changed, 5 insertions(+), 1 deletion(-) > > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > index 905d769d8ddc..5f7eeab990fe 100644 > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -42,7 +42,7 @@ enum { > #define THREAD_ALIGN THREAD_SIZE > #endif > > -#ifdef CONFIG_DEBUG_STACK_USAGE > +#if IS_ENABLED(CONFIG_DEBUG_STACK_USAGE) || IS_ENABLED(CONFIG_DEBUG_KMEMLEAK) > # define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | \ > __GFP_ZERO) > #else > diff --git a/kernel/fork.c b/kernel/fork.c > index c4ff0303b7c5..53e3b6f8a3bf 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -213,6 +213,10 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) > if (!s) > continue; > > +#ifdef CONFIG_DEBUG_KMEMLEAK > + /* Clear stale pointers from reused stack. */ > + memset(s->addr, 0, THREAD_SIZE); > +#endif > tsk->stack_vm_area = s; > return s->addr; > } Acked-by: Catalin Marinas