From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f198.google.com (mail-lb0-f198.google.com [209.85.217.198]) by kanga.kvack.org (Postfix) with ESMTP id 09E046B0005 for ; Thu, 16 Jun 2016 06:59:32 -0400 (EDT) Received: by mail-lb0-f198.google.com with SMTP id js8so25785282lbc.2 for ; Thu, 16 Jun 2016 03:59:31 -0700 (PDT) Received: from mail-wm0-f68.google.com (mail-wm0-f68.google.com. [74.125.82.68]) by mx.google.com with ESMTPS id rn9si4710557wjb.87.2016.06.16.03.59.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Jun 2016 03:59:30 -0700 (PDT) Received: by mail-wm0-f68.google.com with SMTP id m124so10496034wme.3 for ; Thu, 16 Jun 2016 03:59:30 -0700 (PDT) Date: Thu, 16 Jun 2016 12:59:28 +0200 From: Michal Hocko Subject: Re: [PATCH] Revert "mm: rename _count, field of the struct page, to _refcount" Message-ID: <20160616105928.GA12437@dhcp22.suse.cz> References: <1466068966-24620-1-git-send-email-vkuznets@redhat.com> <20160616093235.GA14640@infradead.org> <87eg7xfmtj.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87eg7xfmtj.fsf@vitty.brq.redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Vitaly Kuznetsov Cc: Christoph Hellwig , linux-mm@kvack.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Joonsoo Kim , Andrew Morton , Stephen Rothwell , Vlastimil Babka , Hugh Dickins , Ingo Molnar On Thu 16-06-16 12:30:16, Vitaly Kuznetsov wrote: > Christoph Hellwig writes: > > > On Thu, Jun 16, 2016 at 11:22:46AM +0200, Vitaly Kuznetsov wrote: > >> _count -> _refcount rename in commit 0139aa7b7fa12 ("mm: rename _count, > >> field of the struct page, to _refcount") broke kdump. makedumpfile(8) does > >> stuff like READ_MEMBER_OFFSET("page._count", page._count) and fails. While > >> it is definitely possible to fix this particular tool I'm not sure about > >> other tools which might be doing the same. > >> > >> I suggest we remember the "we don't break userspace" rule and revert for > >> 4.7 while it's not too late. > > > > Err, sorry - this is not "userspace". It's crazy crap digging into > > kernel internal structure. > > > > The rename was absolutely useful, so fix up your stinking pike in kdump. > > Ok, sure, I'll send a patch to it. I was worried about other tools out > there which e.g. inspect /proc/vmcore. As it is something we support > some conservatism around it is justified. struct page layout as some others that such a tool might depend on has changes several times in the past so I fail to see how is it any different this time. struct page is nothing the userspace should depend on. -- Michal Hocko SUSE Labs -- 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