From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753511AbbKWXDK (ORCPT ); Mon, 23 Nov 2015 18:03:10 -0500 Received: from g9t5009.houston.hp.com ([15.240.92.67]:38831 "EHLO g9t5009.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752748AbbKWXDI (ORCPT ); Mon, 23 Nov 2015 18:03:08 -0500 Message-ID: <1448319526.19320.58.camel@hpe.com> Subject: Re: [PATCH] dax: Split pmd map when fallback on COW From: Toshi Kani To: dan.j.williams@intel.com Cc: kirill.shutemov@linux.intel.com, willy@linux.intel.com, ross.zwisler@linux.intel.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@ml01.01.org, linux-kernel@vger.kernel.org Date: Mon, 23 Nov 2015 15:58:46 -0700 In-Reply-To: <1448309120-20911-1-git-send-email-toshi.kani@hpe.com> References: <1448309120-20911-1-git-send-email-toshi.kani@hpe.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 (3.16.5-3.fc22) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2015-11-23 at 13:05 -0700, Toshi Kani wrote: > An infinite loop of PMD faults was observed when attempted to > mlock() a private read-only PMD mmap'd range of a DAX file. Typo: the above description should be (remove "read-only"): An infinite loop of PMD faults was observed when attempted to mlock() a private PMD mmap'd range of a DAX file. -Toshi > __dax_pmd_fault() simply returns with VM_FAULT_FALLBACK when > falling back to PTE on COW. However, __handle_mm_fault() > returns without falling back to handle_pte_fault() because > a PMD map is present in this case. > > Change __dax_pmd_fault() to split the PMD map, if present, > before returning with VM_FAULT_FALLBACK.