From patchwork Mon Nov 23 20:05:20 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kani, Toshi" X-Patchwork-Id: 7685981 Return-Path: X-Original-To: patchwork-linux-nvdimm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D83DDBF90C for ; Mon, 23 Nov 2015 20:09:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1F047207B6 for ; Mon, 23 Nov 2015 20:09:45 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 12A05207EB for ; Mon, 23 Nov 2015 20:09:43 +0000 (UTC) Received: from ml01.vlan14.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 0581C1A207D; Mon, 23 Nov 2015 12:09:43 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from g4t3427.houston.hp.com (g4t3427.houston.hp.com [15.201.208.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 37E6F1A207D for ; Mon, 23 Nov 2015 12:09:42 -0800 (PST) Received: from g4t3433.houston.hp.com (g4t3433.houston.hp.com [16.210.25.219]) by g4t3427.houston.hp.com (Postfix) with ESMTP id 2A12B53; Mon, 23 Nov 2015 20:09:41 +0000 (UTC) Received: from misato.fc.hp.com (misato.fc.hp.com [16.78.168.61]) by g4t3433.houston.hp.com (Postfix) with ESMTP id 2EB672B; Mon, 23 Nov 2015 20:09:40 +0000 (UTC) From: Toshi Kani To: dan.j.williams@intel.com Subject: [PATCH] dax: Split pmd map when fallback on COW Date: Mon, 23 Nov 2015 13:05:20 -0700 Message-Id: <1448309120-20911-1-git-send-email-toshi.kani@hpe.com> X-Mailer: git-send-email 2.4.3 Cc: linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kirill.shutemov@linux.intel.com X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Spam-Status: No, score=-3.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP An infinite loop of PMD faults was observed when attempted to mlock() a private read-only PMD mmap'd range of a DAX file. __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. Signed-off-by: Toshi Kani Cc: Dan Williams Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Ross Zwisler Reviewed-by: Dan Williams --- fs/dax.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 43671b6..3405583 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -546,8 +546,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, return VM_FAULT_FALLBACK; /* Fall back to PTEs if we're going to COW */ - if (write && !(vma->vm_flags & VM_SHARED)) + if (write && !(vma->vm_flags & VM_SHARED)) { + split_huge_page_pmd(vma, address, pmd); return VM_FAULT_FALLBACK; + } /* If the PMD would extend outside the VMA */ if (pmd_addr < vma->vm_start) return VM_FAULT_FALLBACK;