From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from jenni2.inet.fi (mta-out.inet.fi [195.156.147.13]) by ozlabs.org (Postfix) with ESMTP id 894642C0092 for ; Tue, 14 Jan 2014 03:33:27 +1100 (EST) Date: Mon, 13 Jan 2014 18:32:54 +0200 From: "Kirill A. Shutemov" To: "Aneesh Kumar K.V" Subject: Re: [PATCH V4] powerpc: thp: Fix crash on mremap Message-ID: <20140113163254.GA4658@node.dhcp.inet.fi> References: <1389593064-32664-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1389593064-32664-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: aarcange@redhat.com, linux-mm@kvack.org, paulus@samba.org, linuxppc-dev@lists.ozlabs.org, kirill.shutemov@linux.intel.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Jan 13, 2014 at 11:34:24AM +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. > > Signed-off-by: Aneesh Kumar K.V Acked-by: Kirill A. Shutemov -- Kirill A. Shutemov