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 75104C53219 for ; Mon, 27 Jul 2026 12:04:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 855396B009D; Mon, 27 Jul 2026 08:04:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 82CFE6B00A3; Mon, 27 Jul 2026 08:04:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 76A406B00A5; Mon, 27 Jul 2026 08:04:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 56EC16B009D for ; Mon, 27 Jul 2026 08:04:03 -0400 (EDT) Received: from smtpin06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay04.hostedemail.com (Postfix) with ESMTP id D9F3F1A06E5 for ; Mon, 27 Jul 2026 12:04:02 +0000 (UTC) X-FDA: 85034423124.06.43B1E2C Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 310DAA0016 for ; Mon, 27 Jul 2026 12:04:01 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=AXWaNyRr; spf=pass (imf25.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 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=1785153841; b=JgJFYeDCQCM2OEy9SsUopRKvlJVvdDPBbKAU+doGWYgAQ2ZYl0PMMa6bwZU9oeUQw2mtka JrIrHuwVHTI5J8wxsliFjxQPJMxNQA3xqoZtprvNP2hll70S+B7hi/VGJ88kt66Ahe09WY nRv7EQIk0SOLL4urPRiE10wDl2VDJaM= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=AXWaNyRr; spf=pass (imf25.hostedemail.com: domain of ljs@kernel.org designates 172.234.252.31 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=1785153841; 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=D2aJdor0Hpg/4jj2tv4oBgjyWI0Kytt4Ww5CPykH9Pw=; b=ZGfO8D6OqIMQnCZh19Tu5i4xYnYF629CiLOF9PdjfSwpw968kZGJ7mD7YODlGcDg51MBTy rFDeDIbEhs8BZA+Z6kzCjkSkvvk20+A3zATcTqVjqk+Ng7HTvDRvNWFi0+SVtH4BCHMv4l yE2sDtIEWN7VMpQT1TFcMM0MzBD12tM= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 502A740364; Mon, 27 Jul 2026 12:04:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 316601F000E9; Mon, 27 Jul 2026 12:03:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785153840; bh=D2aJdor0Hpg/4jj2tv4oBgjyWI0Kytt4Ww5CPykH9Pw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=AXWaNyRrrKMWJ1IJNk5RXToC/2L4hiE1iNCbYl8psZB8Glfv0hWK7Oez2SFNvZ3FY 1/QbnH/o5rOsHxOr3kZErOTxDUYZ6lqoJMSUdQ0EmsPjNIStps7ipAAwAXKH/m3NFs MITHDis7uQbUkp3Z9jabBs2A4H1gTqHCPmCV468Hxr7i/ZMNrfEuK+9GXs86LuT0gZ BNRA9lMNA6Cvvl4V8D0gYUrNdAveWnRNjUeD+aBxIqjN0Ll18daIR7Cnw1SX29XuTG dErEnkU7cyxLLddSK6WletbqXXvmomBknPSxugnmXwR4XZ5NdhKsWik6ZNFEnrMWih m05vdEyriPRdA== Date: Mon, 27 Jul 2026 13:03:38 +0100 From: "Lorenzo Stoakes (ARM)" To: Gregory Price Cc: Andrew Morton , David Hildenbrand , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , "Matthew Wilcox (Oracle)" , Jan Kara , Miaohe Lin , Naoya Horiguchi , Rik van Riel , Harry Yoo , Lance Yang , Kees Cook , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Usama Arif , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Peter Xu , Xu Xin , Chengming Zhou , Arnd Bergmann , Greg Kroah-Hartman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 01/15] mm/vma: introduce VMA virtual page offset field and add helpers Message-ID: References: <20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org> <20260720-b4-scalable-cow-virt-pgoff-v2-1-2d549757a76f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 310DAA0016 X-Stat-Signature: f1spazgww5ngouna3ku3di4xhok5pob1 X-Rspam-User: X-HE-Tag: 1785153841-616713 X-HE-Meta: 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 whEwnk7W 2UQ59jgSJfmI+JkOIBhb+ySw1mYSU02yNnkhO2ynJbssBl9FszwNx7tGtzvD1UsCwtRQiezUT6JiQzgzEknzg99pHeKjs9x/WIIgMCLbvgvc/Qm/Vi43tPeRjuZjvyE7lV4JNk6pXTyTB+0yvTdssZVNlxLvDMxjb9hAkQZKnoBl0DTGQJLiZT8qvbFmgwkrFNoZUxPK2dGZY4/lJAOlIHvMBDtsan7F0iS6TWbPT4J9Xc829ekmiG6LL+hb+Dgiv8/3ZB5tRpABA1lWNpMi7UqEZAoht9wcgWyfDhconQSyTI1pfX8cc8INPCdr73ZzMn4rHylGYwer4QBI= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 20, 2026 at 01:26:09PM -0400, Gregory Price wrote: > On Mon, Jul 20, 2026 at 05:56:52PM +0100, Lorenzo Stoakes (ARM) wrote: > > On Mon, Jul 20, 2026 at 11:49:00AM -0400, Gregory Price wrote: > > > On Mon, Jul 20, 2026 at 03:38:27PM +0100, Lorenzo Stoakes (ARM) wrote: > > > > > > > > The virtual page offset of a VMA is equal to vma->vm_start >> PAGE_SHIFT if > > > > they are unfaulted or were not remapped, otherwise it is equal to this > > > > value at the point of first fault. > > > > > > > > > > The latter half of this description is a bit confusing. > > > > > > Why would the value differ from (vma->vm_start >> PAGE_SHIFT)? > > > (because it's file backed? > > > > Because the VMA gets remapped. > > > > If it's remapped when it's unfaulted, then virtual page offset gets updated, if > > it's faulted then not. > > > > ahhhhh the wording is just wonky then > > when faulted or remapped, x is... > when unfaulted or unremapped, x is... > > instead of > > x is ... if unfaulted or were not remapped, otherwise... > > Sort of a complex combination of 3 negatives there. > > ~Gregory > Ack, will improve wording! Cheers, Lorenzo