From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753452AbaIDPyl (ORCPT ); Thu, 4 Sep 2014 11:54:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29643 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbaIDPyk (ORCPT ); Thu, 4 Sep 2014 11:54:40 -0400 Date: Thu, 4 Sep 2014 16:52:00 +0100 From: Aaron Tomlin To: Oleg Nesterov Cc: peterz@infradead.org, mingo@redhat.com, dzickus@redhat.com, bmr@redhat.com, jcastillo@redhat.com, pzijlstr@redhat.com, riel@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, x86@kernel.org, rostedt@goodmis.org, hannes@cmpxchg.org, aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, minchan@kernel.org Subject: Re: [PATCH 1/2] sched: Add helper for task stack page overrun checking Message-ID: <20140904155200.GC1436@atomlin.usersys.redhat.com> References: <1409842224-11847-1-git-send-email-atomlin@redhat.com> <1409842224-11847-2-git-send-email-atomlin@redhat.com> <20140904150234.GA6480@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140904150234.GA6480@redhat.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 04, 2014 at 05:02:34PM +0200, Oleg Nesterov wrote: > On 09/04, Aaron Tomlin wrote: > > > > +#define task_stack_end_corrupted(task) \ > > + (*(end_of_stack(task)) != STACK_END_MAGIC) > > and it is always used along with "tsk != init_task". > > But why we exclude swapper/0? Can't we add > > end_of_stack(current) = STACK_END_MAGIC; > > somewhere at the start of start_kernel() ? Good point. I can look into it. > If not, perhaps this new helper should check "task != &init_task" > itself so that we can simplify its users? > > Oleg. > > > > > static inline int object_is_on_stack(void *obj) > > { > > diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c > > index 8a4e5cb..06c7390 100644 > > --- a/kernel/trace/trace_stack.c > > +++ b/kernel/trace/trace_stack.c > > @@ -13,7 +13,6 @@ > > #include > > #include > > #include > > -#include > > > > #include > > > > @@ -171,8 +170,8 @@ check_stack(unsigned long ip, unsigned long *stack) > > i++; > > } > > > > - if ((current != &init_task && > > - *(end_of_stack(current)) != STACK_END_MAGIC)) { > > + if (current != &init_task && > > + task_stack_end_corrupted(current)) { > > print_max_stack(); > > BUG(); > > } > > -- > > 1.9.3 > > > -- Aaron Tomlin