Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756655AbYJVWLG (ORCPT ); Wed, 22 Oct 2008 18:11:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752466AbYJVWKv (ORCPT ); Wed, 22 Oct 2008 18:10:51 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:34271 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751850AbYJVWKu (ORCPT ); Wed, 22 Oct 2008 18:10:50 -0400 To: cl@linux-foundation.org CC: miklos@szeredi.hu, penberg@cs.helsinki.fi, 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: (message from Christoph Lameter on Wed, 22 Oct 2008 14:28:57 -0700 (PDT)) 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: Thu, 23 Oct 2008 00:10:34 +0200 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1217 Lines: 28 On Wed, 22 Oct 2008, Christoph Lameter wrote: > On Wed, 22 Oct 2008, Miklos Szeredi wrote: > > >> 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. > > Plus the allocator may be reusing parts of the freed object for a freelist > etc even if the object is not poisoned. Actually, no: looking at the slub code it already makes sure that objects are neither poisoned, nor touched in any way _if_ there is a constructor for the object. And for good reason too, otherwise a reused object would contain rubbish after a second allocation. Come on guys, you should be the experts in this thing! So again, just checking d_lru should do work fine. There's absolutely no need to mess with extra references in a separate phase, which leads to lots of complications. 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/