From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DB34FC44501 for ; Fri, 10 Jul 2026 14:51:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8BB536B008A; Fri, 10 Jul 2026 10:51:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8921E6B008C; Fri, 10 Jul 2026 10:51:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7D11E6B009B; Fri, 10 Jul 2026 10:51:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 585546B008A for ; Fri, 10 Jul 2026 10:51:12 -0400 (EDT) Received: from smtpin08.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id A21C0A0460 for ; Fri, 10 Jul 2026 14:51:11 +0000 (UTC) X-FDA: 84973154742.08.226FA81 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf29.hostedemail.com (Postfix) with ESMTP id 1B33F12000E for ; Fri, 10 Jul 2026 14:51:09 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GV0G1PCd; spf=pass (imf29.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1783695070; b=l6k80g8vcQtpuhyapDAobj53708BfW1whvIkPaCTMFGmiRYJaEVM0LaO0jkB1+5J6GtB5F ItJWH9rqq6H9yEL9ixdiZD1j3v8DEm4k4ihJP+8zmsqeWRXr2bubFLDevTNHMOUz0WaCBS /x6X0OITjsZMKF+F7y30Ig7fP0EJ+Gs= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GV0G1PCd; spf=pass (imf29.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1783695070; 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=/adl28F1RG11+xFCTzjhiMT3/quSA/55SrYHe5Xl+as=; b=GTIQIfgrkbbm5EdbJSa9ozsG5Lo6/N5+stVJMe0bnggELxJi/3JUQGi5aQ74lR5yGaBwIq vw/6KKDjRWp5M35GBT8hCEimd0F+5GzDQXae9DZ9xWy4crox4gbQuL4tZ/XFm2R/eAyn+l bxrswj3RVRVGa3QJ33bzlhYAsnCpSzQ= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 67B6960051; Fri, 10 Jul 2026 14:51:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A13DE1F00A3A; Fri, 10 Jul 2026 14:50:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783695069; bh=/adl28F1RG11+xFCTzjhiMT3/quSA/55SrYHe5Xl+as=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=GV0G1PCdVWL/17cPDVZfz86GmBO0VpAcpElRSgqzkFaZnFKsDK6rIw+lxzMvM7oyM gOb7BmlLZV+r7XfvVToV0An5vS3DWoiRNZEtakP1kgKdd/pwAzK/AhJrUnpZlFH/ma IDgVC6vlNuOfwFAEke1UlfCP3mMcmRNqv1rAQF1Ta5n8CDc7P/kP23VMlYUdFRkbMx btXD63gJA5fhI4bndbOxrinkAQhHaNvBor7RN1UECzz5h5BotHDkxdGHR0ZdFn1Wle sxRRlN3kLf8W7g8Lmmkim9s7ySe4W1NlivrC5VU8viOWzvoYYPKNt7/4lb6lTsMCz8 i1PWPp9WBYC/w== Date: Fri, 10 Jul 2026 15:50:44 +0100 From: Lorenzo Stoakes To: Gregory Price Cc: Andrew Morton , Russell King , Dinh Nguyen , Simon Schuster , "James E . J . Bottomley" , Helge Deller , Jarkko Sakkinen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Ian Abbott , H Hartley Sweeten , Lucas Stach , David Airlie , Simona Vetter , Patrik Jakobsson , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Clark , Dmitry Baryshkov , Tomi Valkeinen , Thierry Reding , Mikko Perttunen , Jonathan Hunter , Christian Koenig , Huang Rui , Ankit Agrawal , Alex Williamson , Alexander Viro , Christian Brauner , Dan Williams , Muchun Song , Oscar Salvador , David Hildenbrand , Suren Baghdasaryan , "Liam R . Howlett" , Matthew Wilcox , Marek Szyprowski , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Masami Hiramatsu , Oleg Nesterov , Steven Rostedt , SeongJae Park , Miaohe Lin , Hugh Dickins , Mike Rapoport , Kees Cook , Paolo Bonzini , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, linux-sgx@vger.kernel.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, linux-tegra@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-mm@kvack.org, iommu@lists.linux.dev, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, kasan-dev@googlegroups.com, damon@lists.linux.dev, Pedro Falcato , Rik van Riel , Harry Yoo , Jann Horn Subject: Re: [PATCH 13/30] mm/vma: refactor vmg_adjust_set_range() for clarity Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1B33F12000E X-Stat-Signature: zhnpdcgps4o57urai5nzcrbb89sqr6db X-HE-Tag: 1783695069-839255 X-HE-Meta: U2FsdGVkX19LnCNymQh6f9IFH8Ndjfu7Z1qpqclzF7QZGNEzc/CgtisfSlag2TNF/lRFZnEAeWQozftjfSq/hQsuaujdUq1+ooFvXtOILuCvOqJnbCompUJnmtCYWP+3/UDiJupBExdtQpaCp8mTmhTpnz8182x8VGK9del4ZDPCI7Rt2Az7P5WwnnWY1ZvvyhxzMQK/UUUyg12bfYrTufELPIr0xNpwQolKE4YVxoYPymOXDFp7KrMG4TzApG1Vl9SAtwMV40jmx3BAr+NWnb7N9QGnIZTXFp2qv6RzCJ94ace3hekLJhI/qDfrptyTaF24frnQ91LJpTLfZFj9i/qBdCt2GXsXdPPLoCHJyFW5ISyQ6O2R+LWhIKPMXYKf4o8Ia9RoaifVNO97N+N13NBm6mRmwnH7C+TM5Me1EraTVPYkTZObm4QD4xLlu47Kfxz/cjZbj9rpGrw55YVzQiG5A/jZTzTQr0fbrA5f5gxi4ep7BEbec0PHZkGsFooWqzXqkRKUrDg0H44ZrBXXT6pOVrBiT1MaLcL2VPlOL4bWUItmARWTuti7NxR87psjJjc2nwuaFQ6FZ63fPuYPxl8KVl5nCy6k98Qv7ov3u87fdSjCALt6NufDASOVhMOeOG0Agg6h0C2/RlO+GfL1mkmvelOwQLXp+kdCwTTQfO3oU4W+5NcXpgQQG0XxoiMrAMuMdSXRIxuex47BaqgHKVINErNXT75fgJr1XfzAuVYQnjA1YoCflb96XZO9lD9Ukz+ueK7uEUGfg77MbfG1JHZiXqA/Hpf5R0SaoPnsaaIxCgIUhATjR2toAjqzVb1obxiQ0RVQRwrknz10O+aFqG6y8IiEkBxCjU1bFfOF1cFge279Yr2h9UzvsaxzGE/G4WbR0VpajLRmlyHNd8H0fi9w0BkKlx7sYjvs5ag/m+XipLjg7uuKf5JAcIx7Gttct6pmYiv60LOeYp34XXo nHZfC31/ jedMrSJCXIs3poNO5eEt5Z+97bFHsSyWyQ1QARr2oPBqdRyBMYI5nSktAxs0AOucY2tUdQh9frvEU4Ot496r8auk8q+aXhWbbJFjbQYxwM56IQcKrBdXmU1+xSuBWPtJW65Yc04ZDtQbWTogdszSlZf2ZikYmSMyqLGGHcu7wAm9jwnJeUt8Yzh2gw5HOU+xZESBuPEDQmcvM+23sSjEXcZ3OwrrF5QK6X20UOCkhq2rvSscdqEHS7zQy8ClMkOsNJzDHGS6hSYPg/DRofQ1J2WWSDmA1BsVdDLXzBMYAevSAWxQREczhYoyRHOnNE/Vp+PcInWZWZrvy3r79XbC7J+fPTQWicE6CYXrMabFS9wDcCYfLsTA9Kw/iaqutS9YCqYCO+8RiYSsvM+SYm88nf0ABPKzeHxb7L4leXAYDMSTnuma7107fPAIe6DIYeLFalftLqMAQ9Epffdk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 09, 2026 at 11:18:40AM -0400, Gregory Price wrote: > On Mon, Jun 29, 2026 at 01:23:24PM +0100, Lorenzo Stoakes wrote: > > Add comments with ASCII diagrams to describe what we're doing, avoid > > dubious use of PHYS_PFN(), and use vma_start_pgoff(). > > > > The most complicated scenario represented here is vmg->__adjust_next_start > > - when this is set, vmg->[start, end] actually indicate the range to be > > retained, so take special care to describe this accurately. > > > > No functional change intended. > > > > Signed-off-by: Lorenzo Stoakes > > Reviewed-by: Gregory Price > > > + /* > > + * vmg->start vmg->end > > + * | | > > + * v merge v > > + * <-------------> > > + * delta > > + * <------> > > + * |------|----------------| > > + * | prev | middle | > > + * |------|----------------| > > + * ^ > > + * | > > + * middle->vm_start > > + */ > > Even with these diagrams, it's a bit difficult to understand what the > actual intent/result of this chunk is (but that may be a limitation of > me not spending enough time reading the surrounding code, not a comment > of your work here). Yeah I know, I do hope to refactor all this at some point to make it simpler, but for the time being tried to make the confusing thing at least _slightly_ less confusing :) > > ~Gregory Cheers, Lorenzo > > > + /* > > + * Originally: > > + * > > + * vmg->start vmg->end > > + * | | > > + * v merge v > > + * <------------> > > + * . . > > + * merge_existing_range() updates to: > > + * . . > > + * vmg->start vmg->end . > > + * | | . > > + * v retain v . > > + * <----------> . > > + * delta . > > + * <-----> . > > + * |----------------|------| > > + * | middle | next | > > + * |----------------|------| > > + * ^ > > + * | > > + * next->vm_start > > + */