Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754349AbYJVVFv (ORCPT ); Wed, 22 Oct 2008 17:05:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757501AbYJVVEv (ORCPT ); Wed, 22 Oct 2008 17:04:51 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:60961 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758498AbYJVVEt (ORCPT ); Wed, 22 Oct 2008 17:04:49 -0400 To: penberg@cs.helsinki.fi CC: miklos@szeredi.hu, cl@linux-foundation.org, nickpiggin@yahoo.com.au, hugh@veritas.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org In-reply-to: <84144f020810221348j536f0d84vca039ff32676e2cc@mail.gmail.com> (penberg@cs.helsinki.fi) Subject: Re: SLUB defrag pull request? References: <1223883004.31587.15.camel@penberg-laptop> <48FE6306.6020806@linux-foundation.org> <84144f020810221348j536f0d84vca039ff32676e2cc@mail.gmail.com> Message-Id: From: Miklos Szeredi Date: Wed, 22 Oct 2008 23:04:32 +0200 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1094 Lines: 24 On Wed, 22 Oct 2008, Pekka Enberg wrote: > On Wed, Oct 22, 2008 at 11:26 PM, Miklos Szeredi wrote: > > Because you don't _need_ a reliable reference to access the contents > > of the dentry. The dentry is still there after being freed, as long > > as the underlying slab is there and isn't being reused for some other > > purpose. But you can easily ensure that from the slab code. > > > > Hmm? > > Actually, when debugging is enabled, it's customary to poison the > object, for example (see free_debug_processing() in mm/slub.c). So we > really can't "easily ensure" that in the allocator unless we by-pass > all the current debugging code. Thank you, that does actually answer my question. I would still think it's a good sacrifice to no let the dentries be poisoned for the sake of a simpler dentry defragmenter. Miklos -- 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/