From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756565AbZBTDJ5 (ORCPT ); Thu, 19 Feb 2009 22:09:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752740AbZBTDJs (ORCPT ); Thu, 19 Feb 2009 22:09:48 -0500 Received: from hera.kernel.org ([140.211.167.34]:44787 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752726AbZBTDJs (ORCPT ); Thu, 19 Feb 2009 22:09:48 -0500 Message-ID: <499E1E99.6030508@kernel.org> Date: Fri, 20 Feb 2009 12:08:09 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Rusty Russell CC: Ingo Molnar , tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, jeremy@goop.org, cpw@sgi.com Subject: Re: [PATCHSET x86/core/percpu] implement dynamic percpu allocator References: <1234958676-27618-1-git-send-email-tj@kernel.org> <200902192121.55157.rusty@rustcorp.com.au> <20090219110631.GJ2354@elte.hu> <200902192244.15055.rusty@rustcorp.com.au> In-Reply-To: <200902192244.15055.rusty@rustcorp.com.au> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Fri, 20 Feb 2009 03:07:54 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rusty Russell wrote: >>>> Rusty, if the fixes are fine with you i can put those two >>>> commits into tip/core/urgent straight away, the full string of >>>> 10 commits into tip/core/percpu and thus we'd avoid duplicate >>>> (or even conflicting) commits. >>> No, the second one is not .29 material; it's a nice, but >>> theoretical, fix. >> Can it never trigger? > > Actually, checked again. It's not even necessary AFAICT (tho a comment > would be nice): > > for (i = 0; i < pcpu_num_used; ptr += block_size(pcpu_size[i]), i++) { > /* Extra for alignment requirement. */ > extra = ALIGN((unsigned long)ptr, align) - (unsigned long)ptr; > BUG_ON(i == 0 && extra != 0); > > if (pcpu_size[i] < 0 || pcpu_size[i] < extra + size) > continue; > > /* Transfer extra to previous block. */ > if (pcpu_size[i-1] < 0) > pcpu_size[i-1] -= extra; > else > pcpu_size[i-1] += extra; > > pcpu_size[0] is *always* negative: it's marked allocated at initialization > (it's the static per-cpu allocations). > > Sorry I didn't examine more closely, Ah... okay. Right. I took the code and used it in the chunk area allocator where 0 isn't guaranteed to be occupied and saw the problem triggering and then assumed the modalloc allocator shared the same problem. So, unnecessary fix but I think it really needs some explanation. What to do about #tj-percpu? Ingo, do you want me to rebase tree sans the second one? Thanks. -- tejun