From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752290AbeC1IQi (ORCPT ); Wed, 28 Mar 2018 04:16:38 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33774 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751191AbeC1IQd (ORCPT ); Wed, 28 Mar 2018 04:16:33 -0400 Subject: Re: [PATCH v9 05/24] mm: Introduce pte_spinlock for FAULT_FLAG_SPECULATIVE To: David Rientjes Cc: 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, Daniel Jordan , 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 References: <1520963994-28477-1-git-send-email-ldufour@linux.vnet.ibm.com> <1520963994-28477-6-git-send-email-ldufour@linux.vnet.ibm.com> From: Laurent Dufour Date: Wed, 28 Mar 2018 10:15:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18032808-0040-0000-0000-000004463BCC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18032808-0041-0000-0000-000020EA49EB Message-Id: <56b596fe-f235-7033-348b-b0d6c9481f2c@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-28_02:,, 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-1803280084 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/03/2018 23:50, David Rientjes wrote: > On Tue, 13 Mar 2018, Laurent Dufour wrote: > >> 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 8ac241b9f370..21b1212a0892 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -2288,6 +2288,13 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, >> } >> EXPORT_SYMBOL_GPL(apply_to_page_range); >> >> +static bool pte_spinlock(struct vm_fault *vmf) > > inline? You're right. Indeed this was done in the patch 18 : "mm: Provide speculative fault infrastructure", but this has to be done there too, I'll fix that. > >> +{ >> + 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, > > Shouldn't pte_unmap_same() take struct vm_fault * and use the new > pte_spinlock()? done in the next patch, but you already acked it..