From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f47.google.com (mail-wm0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id 1EBCB6B0005 for ; Wed, 27 Jan 2016 02:59:16 -0500 (EST) Received: by mail-wm0-f47.google.com with SMTP id n5so14923464wmn.1 for ; Tue, 26 Jan 2016 23:59:16 -0800 (PST) Received: from e06smtp16.uk.ibm.com (e06smtp16.uk.ibm.com. [195.75.94.112]) by mx.google.com with ESMTPS id vx5si6885535wjc.219.2016.01.26.23.59.14 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 26 Jan 2016 23:59:15 -0800 (PST) Received: from localhost by e06smtp16.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 27 Jan 2016 07:59:14 -0000 Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 09F1A17D805D for ; Wed, 27 Jan 2016 07:59:21 +0000 (GMT) Received: from d06av11.portsmouth.uk.ibm.com (d06av11.portsmouth.uk.ibm.com [9.149.37.252]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0R7xCLp1245538 for ; Wed, 27 Jan 2016 07:59:12 GMT Received: from d06av11.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av11.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0R7xBHt031291 for ; Wed, 27 Jan 2016 00:59:12 -0700 Subject: Re: [PATCH/RFC 3/3] s390: query dynamic DEBUG_PAGEALLOC setting References: <1453799905-10941-1-git-send-email-borntraeger@de.ibm.com> <1453799905-10941-4-git-send-email-borntraeger@de.ibm.com> <20160126181903.GB4671@osiris> <20160127001918.GA7089@js1304-P5Q-DELUXE> <20160127005920.GB7089@js1304-P5Q-DELUXE> From: Christian Borntraeger Message-ID: <56A878CF.7090507@de.ibm.com> Date: Wed, 27 Jan 2016 08:59:11 +0100 MIME-Version: 1.0 In-Reply-To: <20160127005920.GB7089@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim , David Rientjes Cc: Heiko Carstens , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org On 01/27/2016 01:59 AM, Joonsoo Kim wrote: > On Tue, Jan 26, 2016 at 04:36:11PM -0800, David Rientjes wrote: >> On Wed, 27 Jan 2016, Joonsoo Kim wrote: >> >>>> I'd agree if CONFIG_DEBUG_PAGEALLOC only did anything when >>>> debug_pagealloc_enabled() is true, but that doesn't seem to be the case. >>>> When CONFIG_DEBUG_SLAB is enabled, for instance, CONFIG_DEBUG_PAGEALLOC >>>> also enables stackinfo storing and poisoning and it's not guarded by >>>> debug_pagealloc_enabled(). >>>> >>>> It seems like CONFIG_DEBUG_PAGEALLOC enables debugging functionality >>>> outside the scope of the debug_pagealloc=on kernel parameter, so >>>> DEBUG_PAGEALLOC(disabled) actually does mean something. >>> >>> Hello, David. >>> >>> I tried to fix CONFIG_DEBUG_SLAB case on 04/16 of following patchset. >>> >>> http://thread.gmane.org/gmane.linux.kernel.mm/144527 >>> >>> I found that there are more sites to fix but not so many. >>> We can do it. >>> >> >> For the slab case, sure, this can be fixed, but there is other code that >> uses CONFIG_DEBUG_PAGEALLOC to suggest debugging is always enabled and is >> indifferent to debug_pagealloc_enabled(). I find this in powerpc and >> sparc arch code as well as generic vmalloc code. > > Yes, I also found it. > >> >> If we can convert existing users that only check for >> CONFIG_DEBUG_PAGEALLOC to rather check for debug_pagealloc_enabled() and >> agree that it is only enabled for debug_pagealloc=on, then this would seem >> fine. However, I think we should at least consult with those users before >> removing an artifact from the kernel log that could be useful in debugging >> why a particular BUG() happened. > > Yes, at least, non-architecture dependent code (vmalloc, SLAB, SLUB) should > be changed first. If Christian doesn't mind, I will try to fix above 3 > things. Ok. So I will change this as Heiko and Thomas suggested for s390 and x86 and resend these 3 patches. Feel free to work on the other areas. Christian -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org