Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934207AbeALR0q (ORCPT + 1 other); Fri, 12 Jan 2018 12:26:46 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:53798 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934175AbeALR0m (ORCPT ); Fri, 12 Jan 2018 12:26:42 -0500 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 , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com 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, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: [PATCH v6 05/24] mm: Introduce pte_spinlock for FAULT_FLAG_SPECULATIVE Date: Fri, 12 Jan 2018 18:25:49 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18011217-0012-0000-0000-000005A3136E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011217-0013-0000-0000-0000191E7BEC Message-Id: <1515777968-867-6-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-01-12_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1801120238 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: When handling page fault without holding the mmap_sem the fetch of the pte lock pointer and the locking will have to be done while ensuring that the VMA is not touched in our back. So move the fetch and locking operations in a dedicated function. Signed-off-by: Laurent Dufour --- mm/memory.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 868424ab850c..6b2c4732e49d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2438,6 +2438,13 @@ static inline void wp_page_reuse(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); } +static bool pte_spinlock(struct vm_fault *vmf) +{ + vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); + spin_lock(vmf->ptl); + return true; +} + static bool pte_map_lock(struct vm_fault *vmf) { vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, @@ -3805,8 +3812,8 @@ static int do_numa_page(struct vm_fault *vmf) * validation through pte_unmap_same(). It's of NUMA type but * the pfn may be screwed if the read is non atomic. */ - vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); - spin_lock(vmf->ptl); + if (!pte_spinlock(vmf)) + return VM_FAULT_RETRY; if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { pte_unmap_unlock(vmf->pte, vmf->ptl); goto out; @@ -3999,8 +4006,8 @@ static int handle_pte_fault(struct vm_fault *vmf) if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) return do_numa_page(vmf); - vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); - spin_lock(vmf->ptl); + if (!pte_spinlock(vmf)) + return VM_FAULT_RETRY; entry = vmf->orig_pte; if (unlikely(!pte_same(*vmf->pte, entry))) goto unlock; -- 2.7.4