From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753910AbcFPJcj (ORCPT ); Thu, 16 Jun 2016 05:32:39 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:48201 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902AbcFPJch (ORCPT ); Thu, 16 Jun 2016 05:32:37 -0400 Date: Thu, 16 Jun 2016 02:32:35 -0700 From: Christoph Hellwig To: Vitaly Kuznetsov Cc: 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 Subject: Re: [PATCH] Revert "mm: rename _count, field of the struct page, to _refcount" Message-ID: <20160616093235.GA14640@infradead.org> References: <1466068966-24620-1-git-send-email-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466068966-24620-1-git-send-email-vkuznets@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.