From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id 525B36B0100 for ; Wed, 6 Nov 2013 15:34:39 -0500 (EST) Received: by mail-pd0-f173.google.com with SMTP id r10so31987pdi.4 for ; Wed, 06 Nov 2013 12:34:38 -0800 (PST) Received: from psmtp.com ([74.125.245.196]) by mx.google.com with SMTP id z1si7409286pbn.271.2013.11.06.12.34.36 for ; Wed, 06 Nov 2013 12:34:37 -0800 (PST) Date: Wed, 6 Nov 2013 21:34:30 +0100 From: Andreas Herrmann Subject: Re: [PATCH] mm/slub: Switch slub_debug kernel option to early_param to avoid boot panic Message-ID: <20131106203429.GL5661@alberich> References: <20131106184529.GB5661@alberich> <000001422ed8406b-14bef091-eee0-4e0e-bcdd-a8909c605910-000000@email.amazonses.com> <20131106195417.GK5661@alberich> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20131106195417.GK5661@alberich> Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Pekka Enberg , Matt Mackall , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" On Wed, Nov 06, 2013 at 08:54:17PM +0100, Andreas Herrmann wrote: > On Wed, Nov 06, 2013 at 02:16:33PM -0500, Christoph Lameter wrote: > > On Wed, 6 Nov 2013, Andreas Herrmann wrote: > > > > > When I've used slub_debug kernel option (e.g. > > > "slub_debug=,skbuff_fclone_cache" or similar) on a debug session I've > > > seen a panic like: > > > > Hmmm.. That looks like its due to some slabs not having names > > during early boot. kmem_cache_flags is called with NULL as a parameter. > > That's because the slub_debug parameter is not evaluated before > kmem_cache_flags is called. > > Older kernels didn't show this problem. I think the sequence of those > calls has changed. Not sure what patch set has made that change. Please ignore this comment. I revisisted the code and of course you are right. Hmm, now wondering why my patch covered the panic. > > Are you sure that this fixes the issue? Looks like the > > kmem_cache_flag function should fail regardless of how early you set it. > > > > AFAICT the right fix would be: > > That would avoid the panic but I guess it won't enable slub debugging. Ok, the latter is bogus. Of course debugging is switched on. > However I'll test this. Your patch fixed it. Andreas -- 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