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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id r13-20020adfe68d000000b0021018642ff8sm11776063wrm.76.2022.06.27.10.56.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 10:56:12 -0700 (PDT) Date: Mon, 27 Jun 2022 18:56:09 +0100 From: "Dr. David Alan Gilbert" To: James Houghton Cc: Matthew Wilcox , Mike Kravetz , Muchun Song , Peter Xu , David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , Jue Wang , Manish Mishra , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 00/26] hugetlb: Introduce HugeTLB high-granularity mapping Message-ID: References: <20220624173656.2033256-1-jthoughton@google.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.2.5 (2022-05-16) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1656352578; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=7mg0Natnz3fvAeghSvOE7uGBbb8dCDKfIOYVJA1IZdI=; b=HkKCm3Yik9iurnlsmAdxC1p966+sERNqj5sSd2RDqJ6uMzyDA4/Ik1UEuLav8tOv72V5se KVggMvhx1Nqkp+NZ0a218kK555nDLcImOPMXio9WHM0wXpyg//0umbK4kSAdtU+YXzO5NO aBaxhUyvkEw5P1hjmQ3vG1pAkfrT5vo= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LxKwHt8L; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf21.hostedemail.com: domain of dgilbert@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=dgilbert@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1656352578; a=rsa-sha256; cv=none; b=d/5SvRo9c1lgU/Yn9ay1XYBi3QytdUcRC/3ZmBkmHoRQKJ7i7kQrksIbP9qWor0UfYc+Ep CJAzrsW44vLcns9aAD7oWX5EADnBPgCXnsU8vuTjVSo+DTEZpbE6UXZ4F3JkK1ED/qyjK5 cMGwhEUf1mk9vd5XgnUzBqI8B41iqb0= X-Rspamd-Queue-Id: 4B19C1C0005 Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LxKwHt8L; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf21.hostedemail.com: domain of dgilbert@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=dgilbert@redhat.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: d88sxmxkq1f1kj4uenqrqmryh7gy45ck X-HE-Tag: 1656352578-84798 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: * James Houghton (jthoughton@google.com) wrote: > On Fri, Jun 24, 2022 at 11:29 AM Matthew Wilcox wrote: > > > > On Fri, Jun 24, 2022 at 05:36:30PM +0000, James Houghton wrote: > > > [1] This used to be called HugeTLB double mapping, a bad and confusing > > > name. "High-granularity mapping" is not a great name either. I am open > > > to better names. > > > > Oh good, I was grinding my teeth every time I read it ;-) > > > > How does "Fine granularity" work for you? > > "sub-page mapping" might work too. > > "Granularity", as I've come to realize, is hard to say, so I think I > prefer sub-page mapping. :) So to recap the suggestions I have so far: > > 1. Sub-page mapping > 2. Granular mapping > 3. Flexible mapping > > I'll pick one of these (or maybe some other one that works better) for > the next version of this series. Just a name; SPM might work (although may confuse those architectures which had subprotection for normal pages), and at least we can mispronounce it. In 14/26 your commit message says: 1. Faults can be passed to handle_userfault. (Userspace will want to use UFFD_FEATURE_REAL_ADDRESS to get the real address to know which region they should be call UFFDIO_CONTINUE on later.) can you explain what that new UFFD_FEATURE does? Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK