Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751969AbdFIOXZ (ORCPT ); Fri, 9 Jun 2017 10:23:25 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:50302 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751735AbdFIOWC (ORCPT ); Fri, 9 Jun 2017 10:22:02 -0400 From: Laurent Dufour To: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com Subject: [RFC v4 16/20] mm/spf: Don't call user fault callback in the speculative path Date: Fri, 9 Jun 2017 16:21:05 +0200 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1497018069-17790-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1497018069-17790-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17060914-0012-0000-0000-0000054950FE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17060914-0013-0000-0000-000018B88402 Message-Id: <1497018069-17790-17-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-09_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706090251 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1147 Lines: 35 The handle_userfault() function assumes that the mmap_sem is held which is not true in the case of a speculative page fault handling. When doing a speculative page fault, lets retry it in the usual path to call handle_userfault(). Signed-off-by: Laurent Dufour --- mm/memory.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 27e44ebc5440..5b158549789b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3005,6 +3005,8 @@ static int do_anonymous_page(struct vm_fault *vmf) /* Deliver the page fault to userland, check inside PT lock */ if (userfaultfd_missing(vma)) { pte_unmap_unlock(vmf->pte, vmf->ptl); + if (vmf->flags & FAULT_FLAG_SPECULATIVE) + return VM_FAULT_RETRY; return handle_userfault(vmf, VM_UFFD_MISSING); } goto setpte; @@ -3045,6 +3047,8 @@ static int do_anonymous_page(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); mem_cgroup_cancel_charge(page, memcg, false); put_page(page); + if (vmf->flags & FAULT_FLAG_SPECULATIVE) + return VM_FAULT_RETRY; return handle_userfault(vmf, VM_UFFD_MISSING); } -- 2.7.4