From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) by ozlabs.org (Postfix) with ESMTP id B33A72C00BB for ; Wed, 12 Feb 2014 04:30:14 +1100 (EST) Date: Tue, 11 Feb 2014 09:31:29 -0800 From: Greg KH To: "Aneesh Kumar K.V" Subject: Re: [PATCH V2] powerpc: thp: Fix crash on mremap Message-ID: <20140211173129.GB30336@kroah.com> References: <1391781117-19045-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1391781117-19045-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, Feb 07, 2014 at 07:21:57PM +0530, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > This patch fix the below crash > > NIP [c00000000004cee4] .__hash_page_thp+0x2a4/0x440 > LR [c0000000000439ac] .hash_page+0x18c/0x5e0 > ... > Call Trace: > [c000000736103c40] [00001ffffb000000] 0x1ffffb000000(unreliable) > [437908.479693] [c000000736103d50] [c0000000000439ac] .hash_page+0x18c/0x5e0 > [437908.479699] [c000000736103e30] [c00000000000924c] .do_hash_page+0x4c/0x58 > > On ppc64 we use the pgtable for storing the hpte slot information and > store address to the pgtable at a constant offset (PTRS_PER_PMD) from > pmd. On mremap, when we switch the pmd, we need to withdraw and deposit > the pgtable again, so that we find the pgtable at PTRS_PER_PMD offset > from new pmd. > > We also want to move the withdraw and deposit before the set_pmd so > that, when page fault find the pmd as trans huge we can be sure that > pgtable can be located at the offset. > > variant of upstream SHA1: b3084f4db3aeb991c507ca774337c7e7893ed04f > for 3.12 stable series This doesn't look like a "variant", it looks totally different. Why can't I just take the b3084f4db3aeb991c507ca774337c7e7893ed04f patch (and follow-on fix) for 3.12? I _REALLY_ dislike patches that are totally different from Linus's tree in stable trees, it has caused nothing but problems in the past. greg k-h