From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp07.in.ibm.com (e28smtp07.in.ibm.com [122.248.162.7]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id AF6A82C00BE for ; Wed, 12 Feb 2014 13:54:15 +1100 (EST) Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 12 Feb 2014 08:24:12 +0530 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 3DD86E0053 for ; Wed, 12 Feb 2014 08:27:29 +0530 (IST) Received: from d28av02.in.ibm.com (d28av02.in.ibm.com [9.184.220.64]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s1C2s4PL28508388 for ; Wed, 12 Feb 2014 08:24:04 +0530 Received: from d28av02.in.ibm.com (localhost [127.0.0.1]) by d28av02.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s1C2s9HG032533 for ; Wed, 12 Feb 2014 08:24:09 +0530 From: "Aneesh Kumar K.V" To: Benjamin Herrenschmidt , Greg KH Subject: Re: [PATCH V2] powerpc: thp: Fix crash on mremap In-Reply-To: <1392144772.23418.11.camel@pasglop> References: <1391781117-19045-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20140211173129.GB30336@kroah.com> <1392144772.23418.11.camel@pasglop> Date: Wed, 12 Feb 2014 08:24:08 +0530 Message-ID: <87fvnpt50v.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain 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: , Benjamin Herrenschmidt writes: > On Tue, 2014-02-11 at 09:31 -0800, Greg KH wrote: >> 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. > > I don't think it applies... (I tried on an internal tree) but the > affected function changed in 3.13 in various ways. Aneesh, please > provide a more details explanation and whether we should backport those > other changes too or whether this is not necessary Yes the affected function added support for split ptl locks for huge pte. I don't think that is a stable material. . > > BTW. Aneesh, we need a 3.11.x one too > 3.11.x it is already applied. -aneesh