From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 6A39C6B02D9 for ; Wed, 7 Feb 2018 02:39:20 -0500 (EST) Received: by mail-pl0-f71.google.com with SMTP id b34so3208320plc.2 for ; Tue, 06 Feb 2018 23:39:20 -0800 (PST) Received: from out02.mta.xmission.com (out02.mta.xmission.com. [166.70.13.232]) by mx.google.com with ESMTPS id m6si601479pgr.468.2018.02.06.23.39.19 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Feb 2018 23:39:19 -0800 (PST) From: ebiederm@xmission.com (Eric W. Biederman) References: <87wozwi0p1.fsf@xmission.com> <0f1bdb63-60d5-467c-a6a4-c06ba62b1f6e@oracle.com> Date: Wed, 07 Feb 2018 01:38:40 -0600 In-Reply-To: <0f1bdb63-60d5-467c-a6a4-c06ba62b1f6e@oracle.com> (Khalid Aziz's message of "Fri, 2 Feb 2018 07:59:25 -0700") Message-ID: <87h8qtfdvj.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH v11 00/10] Application Data Integrity feature introduced by SPARC M7 Sender: owner-linux-mm@kvack.org List-ID: To: Khalid Aziz Cc: davem@davemloft.net, dave.hansen@linux.intel.com, aarcange@redhat.com, akpm@linux-foundation.org, allen.pais@oracle.com, anthony.yznaga@oracle.com, arnd@arndb.de, babu.moger@oracle.com, benh@kernel.crashing.org, bob.picco@oracle.com, bsingharora@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, dave.jiang@intel.com, david.j.aldridge@oracle.com, elena.reshetova@intel.com, glx@linutronix.de, gregkh@linuxfoundation.org, hannes@cmpxchg.org, hillf.zj@alibaba-inc.com, hpa@zytor.com, hughd@google.com, imbrenda@linux.vnet.ibm.com, jack@suse.cz, jag.raman@oracle.com, jane.chu@oracle.com, jglisse@redhat.com, jroedel@suse.de, khalid@gonehiking.org, khandual@linux.vnet.ibm.com, kirill.shutemov@linux.intel.com, kstewart@linuxfoundation.org, ktkhai@virtuozzo.com, liam.merwick@oracle.com, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux@roeck-us.net, me@tobin.cc, mgorman@suse.de, mgorman@techsingularity.net, mhocko@suse.com, mike.kravetz@oracle.com, minchan@kernel.org, mingo@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, nadav.amit@gmail.com, nagarathnam.muthusamy@oracle.com, nborisov@suse.com, n-horiguchi@ah.jp.nec.com, nick.alcock@oracle.com, nitin.m.gupta@oracle.com, ombredanne@nexb.com, pasha.tatashin@oracle.com, paulus@samba.org, pombredanne@nexb.com, punit.agrawal@arm.com, rob.gardner@oracle.com, ross.zwisler@linux.intel.com, shannon.nelson@oracle.com, shli@fb.com, sparclinux@vger.kernel.org, steven.sistare@oracle.com, tglx@linutronix.de, thomas.tai@oracle.com, tklauser@distanz.ch, tom.hromatka@oracle.com, vegard.nossum@oracle.com, vijay.ac.kumar@oracle.com, willy@infradead.org, x86@kernel.org, zi.yan@cs.rutgers.edu Khalid Aziz writes: > On 02/01/2018 07:29 PM, ebiederm@xmission.com wrote: >> Khalid Aziz writes: >> >>> V11 changes: >>> This series is same as v10 and was simply rebased on 4.15 kernel. Can >>> mm maintainers please review patches 2, 7, 8 and 9 which are arch >>> independent, and include/linux/mm.h and mm/ksm.c changes in patch 10 >>> and ack these if everything looks good? >> >> I am a bit puzzled how this differs from the pkey's that other >> architectures are implementing to achieve a similar result. >> >> I am a bit mystified why you don't store the tag in a vma >> instead of inventing a new way to store data on page out. > > Hello Eric, > > As Steven pointed out, sparc sets tags per cacheline unlike pkey. This results > in much finer granularity for tags that pkey and hence requires larger tag > storage than what we can do in a vma. *Nod* I am a bit mystified where you keep the information in memory. I would think the tags would need to be stored per cacheline or per tlb entry, in some kind of cache that could overflow. So I would be surprised if swapping is the only time this information needs stored in memory. Which makes me wonder if you have the proper data structures. I would think an array per vma or something in the page tables would tend to make sense. But perhaps I am missing something. >> Can you please use force_sig_fault to send these signals instead >> of force_sig_info. Emperically I have found that it is very >> error prone to generate siginfo's by hand, especially on code >> paths where several different si_codes may apply. So it helps >> to go through a helper function to ensure the fiddly bits are >> all correct. AKA the unused bits all need to be set to zero before >> struct siginfo is copied to userspace. >> > > What you say makes sense. I followed the same code as other fault handlers for > sparc. I could change just the fault handlers for ADI related faults. Would it > make more sense to change all the fault handlers in a separate patch and keep > the code in arch/sparc/kernel/traps_64.c consistent? Dave M, do you have a > preference? It is my intention post -rc1 to start sending out patches to get the rest of not just sparc but all of the architectures using the new helpers. I have the code I just ran out of time befor the merge window opened to ensure everything had a good thorough review. So if you can handle the your new changes I expect I will handle the rest. Eric -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org