From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754628Ab1ECTL1 (ORCPT ); Tue, 3 May 2011 15:11:27 -0400 Received: from smtp-out.google.com ([216.239.44.51]:62806 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754555Ab1ECTL0 (ORCPT ); Tue, 3 May 2011 15:11:26 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=gduRZ2K7J0JOQoZcOqe874DmztD94MVGqwjMCGFuExscqwtWruAQdw/8A9hWayhxgp acYEhoMyCDBS3sIixfhQ== Date: Tue, 3 May 2011 12:11:28 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@sister.anvils To: Michal Hocko cc: Andrew Morton , linux-mm@kvack.org, LKML Subject: Re: [PATCH resend] mm: get rid of CONFIG_STACK_GROWSUP || CONFIG_IA64 In-Reply-To: <20110503141044.GA25351@tiehlicka.suse.cz> Message-ID: References: <20110503141044.GA25351@tiehlicka.suse.cz> User-Agent: Alpine 2.00 (LSU 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Michal, On Tue, 3 May 2011, Michal Hocko wrote: > Hi Andrew, > the patch bellow probably got lost in the huge "parisc crashes with slub" > thread triggered by my earlier clean up in this area so I am resending > it standalone. > --- > From 2e79c7e73a39a09389a84a8f37eb2a2f2f2859f5 Mon Sep 17 00:00:00 2001 > From: Michal Hocko > Date: Tue, 19 Apr 2011 11:11:41 +0200 > Subject: [PATCH] mm: get rid of CONFIG_STACK_GROWSUP || CONFIG_IA64 > > IA64 needs some trickery for Register Backing Store so we have to > export expand_stack_upwards for it even though the architecture expands > its stack downwards normally. > We have defined VM_GROWSUP which is defined only for the above > configuration so let's use it everywhere rather than hardcoded > CONFIG_STACK_GROWSUP || CONFIG_IA64 > > Signed-off-by: Michal Hocko Sorry to be negative, but this seems more clever than helpful to me: it does not optimize anything (apart from saving a few bytes in mm/mmap.c itself), obscures the special IA64 case, and relies upon the ways in which we happen to define VM_GROWSUP elsewhere. Not a nack: others may well disagree with me. And, though I didn't find time to comment on your later "symmetrical" patch before it went into mmotm, I didn't see how renaming expand_downwards and expand_upwards to expand_stack_downwards and expand_stack_upwards was helpful either - needless change, and you end up using expand_stack_upwards on something which is not (what we usually call) the stack. Now, if you're looking to make a nice cleanup, how about getting rid of find_vma_prev(), which Linus made redundant when he suddenly added vm_prev in 2.6.36? There's at least one place where I apologize for its expense in a BUG_ON, I'd be glad to see that killed off. Hey, but it's certainly not for me to assign work to you! Hugh > --- > mm/mmap.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/mmap.c b/mm/mmap.c > index 29c68b0..3ff9edf 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1726,7 +1726,7 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns > return 0; > } > > -#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) > +#if VM_GROWSUP > /* > * PA-RISC uses this for its stack; IA64 for its Register Backing Store. > * vma is the last one with address > vma->vm_end. Have to extend vma. > @@ -1777,7 +1777,7 @@ int expand_stack_upwards(struct vm_area_struct *vma, unsigned long address) > khugepaged_enter_vma_merge(vma); > return error; > } > -#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ > +#endif /* VM_GROWSUP */ > > /* > * vma is the first one with address < vma->vm_start. Have to extend vma. > -- > 1.7.4.4