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 5833BC531D0 for ; Mon, 27 Jul 2026 12:05:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 45EAE6B00D0; Mon, 27 Jul 2026 08:04:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 436E96B00D1; Mon, 27 Jul 2026 08:04:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 34CE76B00D2; Mon, 27 Jul 2026 08:04:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0F8F26B00D0 for ; Mon, 27 Jul 2026 08:04:59 -0400 (EDT) Received: from smtpin27.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 892831406E7 for ; Mon, 27 Jul 2026 12:04:58 +0000 (UTC) X-FDA: 85034425476.27.0975707 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf12.hostedemail.com (Postfix) with ESMTP id CEE6E40007 for ; Mon, 27 Jul 2026 12:04:56 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fo4Rpc5X; spf=pass (imf12.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=1785153896; 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=r/Y4BMKQ7cvWOkrCWMFKBxy8h6yza/pHmvLf8+MWpC0=; b=hQHToaSyu3CTOYXGGRCPjzumMWPxDCagq+uJk49RbBWF9toeqKUHerABnTywGY1zdY4Fro sTFC0SMB62Mil8lyjGJfA9Jo6J4XUuHIXHtm+kCr/NrswzLSfYNhb7+XJQc3F1cjgQISMu eBokzPRFsmzJ5KLdu5+AJEc7KwCnNSs= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785153896; b=D74+EbHq+jsA0XI+z5sQSlqYqT9qNy+fj8e0XFJxUztz82L6oMIZaJ3aVftjBiXs8Oq63Y YzJSv0NyT9ZN5p0HhPcXcimHbS0g0cV2z7A2ZkUKNzfuSYASRBxdAyc3D10Vl/HfykwrUE UGOF6cqi1qjyIYf9lOLfLbxFRzdIMbs= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fo4Rpc5X; spf=pass (imf12.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 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1E4C141E93; Mon, 27 Jul 2026 12:04:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C13E1F000E9; Mon, 27 Jul 2026 12:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785153896; bh=r/Y4BMKQ7cvWOkrCWMFKBxy8h6yza/pHmvLf8+MWpC0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=fo4Rpc5XZE/gO7ztNgbEH/pgiIOPr/zvBxaoQr4BSg1RSpCdgvR1BqCMiVo1vnn+p BNt2HreMH4K90PYfv2tC8FtD7a050B8K9yKCxsiLzjaRVHw0nq+lioDOLHraXJKj2L gmzEsWNAEN8i8jTiZHhn3ozfLum9UNBed8Tr4PWmgVQRPqIBGLkiVe0qa2G5geMXdT 3u2lL4F+vFvb6TDUKi5dMHS7ltztpsh9E1f0rEVvmWwisGnjlpd5cPNxoSPmUql0AN JcIR/yIDKpAm1+4ZcAxz4nlNdlAhQxEW+JzN8k4CM1O58zuRkXFcKpr66D+SgJrzc5 ECd0XnkJVmXow== Date: Mon, 27 Jul 2026 13:04:35 +0100 From: "Lorenzo Stoakes (ARM)" To: Andrew Morton Cc: 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 , Gregory Price , 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 00/15] mm/rmap: index MAP_PRIVATE file-backed folios by virt pgoff Message-ID: References: <20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org> <20260720124812.30e04cc81a56dd6f0346cdf6@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260720124812.30e04cc81a56dd6f0346cdf6@linux-foundation.org> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CEE6E40007 X-Stat-Signature: aem1fs67bkm3to34w1qz4dxngk4xbjtf X-Rspam-User: X-HE-Tag: 1785153896-215204 X-HE-Meta: U2FsdGVkX19Zr72xpq1gikdNu87LeYRHKhZNmXe+k1fP0bRtPqYNQdqEHpo+O+2E2GvYbL5KBOxOY+W+FX6ElkAyjkBCU4pm1+twhURcJgCUdXBZiiTvemIyxPSlgQvRNwgMG+cxe76r2a4INpFYaCv9SAlRPoU/wIkjzWB/BtMdMkoknGyFbagwhxPL9c2SqKppNYBWYJdlqUVr7eV3JFNPuyQeojSRGZz+GbvI/pPm3l+cDWsISRc05bBEOA9BjqWQUZZyK95TF+UuP6PCWp/MYaSbgUWBndWiMpFw/VTL6gBE9cyBR/h+VPhBmvG7d2tZISR9mPk3shZhV0TLxt6qPpSXyINXFELVD2wez+JpPmqi9SatNMSWfwWvfAMMCZ6asIIkaPZcHBx07ZIQWpCxo2APmqwCNg1DoThVMi3NYnORa1oDSEzSBFtEEVa7Hxot/7RMaMfO4Qik1JLxL+xKIV7uBqjsL3uh/AHcQOamlM7Yi95n2jvqHg9cd3kCdW7RwWt3IOQmq2zg/O/CYsMvmBV0aCvTvGBomJCQTI9Xzmu9jpmroFtdUCys2Y34odUgJQV0P01qfGuA2nROvbANL2UGqCU2Vi7HD5NMefxvpZcKL03/j1XmVYhdhk57wcey7wiQVZmA1ouXgmCHG2kQclJxHGaD43Cic9HHyneQYnkGvzKeuSXYY6AAyHNmhXzRsAzVIa6U/IJ7hf15wB0aSJXrMhUf8mx7CmFBRwDLSp29tF2Q98xiW79c0wqmxCJvaiiSqbyHFC5xQFD6ZLb798VZwnVxleEn9WRxQc5d5FUkHFbBGy23BMvn08wImGsY18V4C0Z3gadZ4t/AY4VDBL/8c//DjouEWqnEfvTErVodmY2BZQKJkc8xwka+NUMGmbw6pPW17oc22k/gYHJ7Rzj/Fx9hT6/xdKGGOVqeFe/tNJ1M3I5jkMTqe/R3JQDfYK+X7bH+upsETDf lBOm7o0J 6vR1iK2b/JB++Y8FW8S0br790d2o9LkdT23f/1FioG/jixvRN1RHijE+vh1eJwrWyRbXxHdl/8bc43hi9S3XyvRQwQl7CCRJJNm+kEYvSWUHD3fEGsyRLgl+dDaXGd64sfH9IDtp5vnH2xbTLGP2awIK7StUVYrvK/vWCLoke1RYpH/6shS7JmR+5Kq5tXBDhd8yLbEDzKhDvkLLIZwfITV+AAHpoJLb3mKASANdbatYTJCeLdU1XNiv1eWRId4dXt28hh5DBdZUJiAhQxMEWG+ilBxqVdIwQgJiZErCQr9K9CaqyIHXcDn/euGmIBBmEGjSYn4pw79scGBQh6z2eYYwS2IMPq37bQI94NxDAnPs48Ude/Ig2w/bg3xUEJrsVpV/RzauWHkvPgeUYZ3HgZvwoTXfNlrSiy3T/cTQrckYnaGHZaNrS6raJLvlpCjWs3YhsbGmArm61gKg= 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 12:48:12PM -0700, Andrew Morton wrote: > On Mon, 20 Jul 2026 15:38:26 +0100 "Lorenzo Stoakes (ARM)" wrote: > > > In memory management we've managed to manufacture a great deal of confusion > > around the concept of anonymous memory. We have: > > > > 1. 'Pure anon' memory - anonymous VMAs whose folios are anonymous and > > swap-backed (thus for reclaim purposes, treated as anonymous). These are > > simple enough. > > > > 2. shmem - file-backed VMAs, file-backed folios (from rmap perspective) so > > present in the page cache and mapped by an address_space object, but > > whose folios are also swap-backed (thus treated as anonymous for reclaim > > purposes). > > > > 3. MAP_PRIVATE-mapped /dev/zero - a strange beast whose VMAs have > > vma->vm_file set, but whose mmap_prepare callback clears vma->vm_ops to > > satisfy vma_is_anonymous(), which results in VMAs that were mmap()'d > > referencing a file, but are in every other sense anonymous, including the > > folios. > > > > 4. Other MAP_PRIVATE-file backed mappings - These possess file-backed VMAs > > and have file-backed folios until CoW'd, at which point those CoW'd > > folios are anonymous. > > > > This series fixes issues 3 and 4. > > Thanks, I'll add this to mm-new for review-n-test. > > AI review seems overloaded at present, might have found a few things: > https://sashiko.dev/#/patchset/20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org > Thanks, will have a look through the sashiko stuff and see what's valid. Cheers, Lorenzo