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[91.159.62.242]) by smtp.gmail.com with ESMTPSA id e14-v6sm672120ljl.43.2018.10.31.16.10.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 31 Oct 2018 16:10:32 -0700 (PDT) Subject: Re: [PATCH 10/17] prmem: documentation To: Andy Lutomirski , Peter Zijlstra Cc: Matthew Wilcox , Tycho Andersen , Kees Cook , Mimi Zohar , Dave Chinner , James Morris , Michal Hocko , Kernel Hardening , linux-integrity , LSM List , Igor Stoppa , Dave Hansen , Jonathan Corbet , Laura Abbott , Randy Dunlap , Mike Rapoport , "open list:DOCUMENTATION" , LKML , Thomas Gleixner References: <0A7AFB50-9ADE-4E12-B541-EC7839223B65@amacapital.net> <20181030175814.GB10491@bombadil.infradead.org> <20181030182841.GE7343@cisco> <20181030192021.GC10491@bombadil.infradead.org> <9edbdf8b-b5fb-5a82-43b4-b639f5ec8484@gmail.com> <20181030213557.GE10491@bombadil.infradead.org> <20181031100237.GN744@hirez.programming.kicks-ass.net> <659CFC78-22BF-492B-B2E4-B8E89AA08446@amacapital.net> <20181031210032.GA3159@hirez.programming.kicks-ass.net> <2E29C35B-3F98-473D-A874-0D9B9B15B399@amacapital.net> From: Igor Stoppa Message-ID: <4124995b-4363-9b37-19b1-1879bf04978b@gmail.com> Date: Thu, 1 Nov 2018 01:10:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <2E29C35B-3F98-473D-A874-0D9B9B15B399@amacapital.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On 01/11/2018 00:57, Andy Lutomirski wrote: > > >> On Oct 31, 2018, at 2:00 PM, Peter Zijlstra wrote: >> I _think_ the use-case for atomics is updating the reference counts of >> objects that are in this write-rare domain. But I'm not entirely clear >> on that myself either. I just really want to avoid duplicating that >> stuff. > > Sounds nuts. Doing a rare-write is many hundreds of cycles at best. Using that for a reference count sounds wacky. > > Can we see a *real* use case before we over complicate the API? > Does patch #14 of this set not qualify? ima_htable.len ? https://www.openwall.com/lists/kernel-hardening/2018/10/23/20 -- igor