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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 24 Apr 2019 11:34:39 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3OAYbhp60227612 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Apr 2019 10:34:37 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8B5EFA405D; Wed, 24 Apr 2019 10:34:37 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D6834A404D; Wed, 24 Apr 2019 10:34:34 +0000 (GMT) Received: from [9.145.184.124] (unknown [9.145.184.124]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 24 Apr 2019 10:34:34 +0000 (GMT) Subject: Re: [PATCH v12 04/31] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT To: Mark Rutland Cc: Jerome Glisse , akpm@linux-foundation.org, mhocko@kernel.org, peterz@infradead.org, kirill@shutemov.name, ak@linux.intel.com, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , aneesh.kumar@linux.ibm.com, benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , sergey.senozhatsky.work@gmail.com, Andrea Arcangeli , Alexei Starovoitov , kemi.wang@intel.com, Daniel Jordan , David Rientjes , Ganesh Mahendran , Minchan Kim , Punit Agrawal , vinayak menon , Yang Shi , zhong jiang , Haiyan Song , Balbir Singh , sj38.park@gmail.com, Michel Lespinasse , Mike Rapoport , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, npiggin@gmail.com, paulmck@linux.vnet.ibm.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org References: <20190416134522.17540-1-ldufour@linux.ibm.com> <20190416134522.17540-5-ldufour@linux.ibm.com> <20190416142710.GA54515@lakrids.cambridge.arm.com> <4ef9ff4b-2230-0644-2254-c1de22d41e6c@linux.ibm.com> <20190416144156.GB54708@lakrids.cambridge.arm.com> <20190418215113.GD11645@redhat.com> <73a3650d-7e9f-bc9e-6ea1-2cef36411b0c@linux.ibm.com> <20190423161931.GE56999@lakrids.cambridge.arm.com> From: Laurent Dufour Date: Wed, 24 Apr 2019 12:34:34 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190423161931.GE56999@lakrids.cambridge.arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19042410-0016-0000-0000-00000272F61E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042410-0017-0000-0000-000032CF66F9 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-24_07:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904240088 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Le 23/04/2019 à 18:19, Mark Rutland a écrit : > On Tue, Apr 23, 2019 at 05:36:31PM +0200, Laurent Dufour wrote: >> Le 18/04/2019 à 23:51, Jerome Glisse a écrit : >>> On Tue, Apr 16, 2019 at 03:41:56PM +0100, Mark Rutland wrote: >>>> On Tue, Apr 16, 2019 at 04:31:27PM +0200, Laurent Dufour wrote: >>>>> Le 16/04/2019 à 16:27, Mark Rutland a écrit : >>>>>> On Tue, Apr 16, 2019 at 03:44:55PM +0200, Laurent Dufour wrote: >>>>>>> From: Mahendran Ganesh >>>>>>> >>>>>>> Set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT for arm64. This >>>>>>> enables Speculative Page Fault handler. >>>>>>> >>>>>>> Signed-off-by: Ganesh Mahendran >>>>>> >>>>>> This is missing your S-o-B. >>>>> >>>>> You're right, I missed that... >>>>> >>>>>> The first patch noted that the ARCH_SUPPORTS_* option was there because >>>>>> the arch code had to make an explicit call to try to handle the fault >>>>>> speculatively, but that isn't addeed until patch 30. >>>>>> >>>>>> Why is this separate from that code? >>>>> >>>>> Andrew was recommended this a long time ago for bisection purpose. This >>>>> allows to build the code with CONFIG_SPECULATIVE_PAGE_FAULT before the code >>>>> that trigger the spf handler is added to the per architecture's code. >>>> >>>> Ok. I think it would be worth noting that in the commit message, to >>>> avoid anyone else asking the same question. :) >>> >>> Should have read this thread before looking at x86 and ppc :) >>> >>> In any case the patch is: >>> >>> Reviewed-by: Jérôme Glisse >> >> Thanks Mark and Jérôme for reviewing this. >> >> Regarding the change in the commit message, I'm wondering if this would be >> better to place it in the Series's letter head. >> >> But I'm fine to put it in each architecture's commit. > > I think noting it in both the cover letter and specific patches is best. > > Having something in the commit message means that the intent will be > clear when the patch is viewed in isolation (e.g. as they will be once > merged). > > All that's necessary is something like: > > Note that this patch only enables building the common speculative page > fault code such that this can be bisected, and has no functional > impact. The architecture-specific code to make use of this and enable > the feature will be addded in a subsequent patch. Thanks Mark, will do it this way. > Thanks, > Mark.