Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752934AbbDBSBj (ORCPT ); Thu, 2 Apr 2015 14:01:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35363 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbbDBSBi (ORCPT ); Thu, 2 Apr 2015 14:01:38 -0400 Message-ID: <551D83DD.5010200@redhat.com> Date: Thu, 02 Apr 2015 14:01:01 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Frederic Weisbecker , LKML CC: Peter Zijlstra , Dave Jones , Thomas Gleixner , Oleg Nesterov , "Paul E . McKenney" , Ingo Molnar Subject: Re: [PATCH 1/3] context_tracking: Protect against recursion References: <1427996365-12101-1-git-send-email-fweisbec@gmail.com> <1427996365-12101-2-git-send-email-fweisbec@gmail.com> In-Reply-To: <1427996365-12101-2-git-send-email-fweisbec@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 30 On 04/02/2015 01:39 PM, Frederic Weisbecker wrote: > Context tracking recursion can happen when an exception triggers in the > middle of a call to a context tracking probe. > > This special case can be caused by vmalloc faults. If an access to a > memory area allocated by vmalloc happens in the middle of > context_tracking_enter(), we may run into an endless fault loop because > the exception in turn calls context_tracking_enter() which faults on > the same vmalloc'ed memory, triggering an exception again, etc... > > Some rare crashes have been reported so lets protect against this with > a recursion counter. > > Reported-by: Dave Jones > Signed-off-by: Frederic Weisbecker > Cc: Thomas Gleixner > Cc: Peter Zijlstra > Cc: Rik van Riel > Cc: Paul E. McKenney > Cc: Ingo Molnar > Cc: Dave Jones > Cc: Oleg Nesterov Reviewed-by: Rik van Riel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/