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 84A31C55822 for ; Wed, 5 Aug 2026 09:02:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 87BE06B00A7; Wed, 5 Aug 2026 05:02:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 82B996B00AA; Wed, 5 Aug 2026 05:02:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 769406B00AB; Wed, 5 Aug 2026 05:02:08 -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 54FC06B00A7 for ; Wed, 5 Aug 2026 05:02:08 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id DD9EF40406 for ; Wed, 5 Aug 2026 09:02:07 +0000 (UTC) X-FDA: 85066623894.28.1DCFDC1 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf01.hostedemail.com (Postfix) with ESMTP id 3C57840009 for ; Wed, 5 Aug 2026 09:02:06 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FvDWd5gL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785920526; 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=66l5hkhMF3qY+C/lhEJTwIWDv2T0Sfe1Ujylj6oShM0=; b=qplqELBaeCy1FuHSI87hZFdsce+lUaOLQXqOIh9ZggrOn/nwnV2AZcLMy58SrNHSU/A4QK OPIv88JpJmvnqT4cYOfNEjCce7kK35U/ogP3Fiu3AiJzOBvF2twISJetDHVwP/VTib0iLD 1Y2ejgnqQXn6JqPZmwbgOs6yuN6B62A= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=FvDWd5gL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf01.hostedemail.com: domain of ljs@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=ljs@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785920526; b=2Z6Menj0MBUHtASEcfrtgicBsNvPY7jiXvSusBZ+sxXCHOWtUMvgFVc/mJX8/psoiW0lID Gx6fs5ar3quUHipGKfUFEYaurwpNVsovpOEHmERL/eJzMtYIkOZ7JxmRDFN5Pb06FnTQJv nFz2H6vnPQsRwuMuokzwiXp8MdBctqY= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id A6FC2600B1; Wed, 5 Aug 2026 09:02:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB51B1F000E9; Wed, 5 Aug 2026 09:01:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785920525; bh=66l5hkhMF3qY+C/lhEJTwIWDv2T0Sfe1Ujylj6oShM0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=FvDWd5gLedAF3nNnMaCJ9oirgJhxdVx4jBcpZAAzC0qzYO75osbFDc+BfDmdihS7j B1UKpRlg48RQxGFsStggVP+zgbFlW2Ek5FaO2J1gJ4nECj/WeZvwy6nMaCsdvhoR8j HRty18X26LmzDYN+W3OtJe+e2D5kawLQcV2/OLCbOZsGqfyp7bFqbgY0Ai0PLf4jMv 37COKCxILOlCdxvUYreRvTwSZnqe6W2r2ctkzSTaU4hRzCGxPIYXGwhDWD+qSrRbdF NntzsRY/ogQRIztXPjMjddwT4tyIGNz8z+DpWOzrwbSvvhCeP8X9T1zlfDPvMxeSRx B49VqHoTzImaQ== Date: Wed, 5 Aug 2026 10:01:43 +0100 From: "Lorenzo Stoakes (ARM)" To: Gregory Price Cc: "David Hildenbrand (Arm)" , Andrew Morton , "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 v3 04/15] mm: update print_bad_page_map() to show anonymous page index Message-ID: References: <20260729-b4-scalable-cow-virt-pgoff-v3-0-e8ecfefea812@kernel.org> <20260729-b4-scalable-cow-virt-pgoff-v3-4-e8ecfefea812@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: ekaymufnbf66wk9989iegycqaoj1zamf X-Rspamd-Queue-Id: 3C57840009 X-HE-Tag: 1785920526-407168 X-HE-Meta: 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 CyPwPvKc xih3qJOSdzTgZzWUrg0e/lT5F+mELa1snhHA1qmuyJrXYCGYwQmv1fdNW8PclFkCWT6h5q+6a2uDlxmQrUWVHPwfqKOGpNeIJouHzNBn0wQMraTC2FjlBFWfKpdPyKCQQGb5V2dClodxHK3CklNh60m0At/FSstWaCsWY7hrJaGm10bOUXtJg681GeKlYjwsPtf8FivPWT5bUMJ8cHmPbElYDczQTRWAzoSbcbX8Hnb6rhPm5leoLbvmH+iqa065PHYy7mjJwJ+g70rRb+98oPUuMLacwHFpGigW0U6Jc7rAwARv1k9jiLn+RkQhwMTGUQ0EHGJxN+aeJMFlDe5sUyT5StniMLPjfDlsc2WYhCt978Z2+tbxwgEq7QQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Aug 05, 2026 at 04:30:18AM -0400, Gregory Price wrote: > On Mon, Aug 03, 2026 at 11:19:17AM +0100, Lorenzo Stoakes (ARM) wrote: > > On Mon, Aug 03, 2026 at 11:39:11AM +0200, David Hildenbrand (Arm) wrote: > > > On 7/30/26 08:32, Gregory Price wrote: > > > > On Wed, Jul 29, 2026 at 05:48:39PM +0100, Lorenzo Stoakes (ARM) wrote: > > > >> This is potentially useful debugging information and matches the existing > > > >> page offset provided. > > > >> > > > >> Use the raw __linear_anon_page_index() function so as to always output this > > > >> value regardless of whether the mapping is file-backed or not. > > > >> > > > > > > > > Begs the question whether we should mark the value based on whether > > > > it is file backed or not, but i suppose you can gleen that from the > > > > other printed values (anon_mem, mapping, vm_ops, etc). > > > > > > You mean something anon_pgoff_t or what did you have in mind? > > > > I suspect he means e.g. adding a (A) suffix or something? Like page offset xxx > > (F) or yyy (A) I guess? > > > > Yeah just an F/A in the print I suppose. Sorry if that was unclear. > > If it saves someone the head-scratch of whether some bug is because it's > "file" or "true anon", given the ambiguity here, seems like maybe useful > debug information. Yeah will do on respin I think actually! I do think not providing that could result in some confusion like 'hm I thought this was file-backed'. (We've made our lives hard with varying definitions of 'anon' also... [shmem being 'anon in page cache' is especially lol] so it's already confusing but there we go :) I will add a comment explaining things so if anybody still wonders what's going on they can see what's up in the code. > > ~Gregory -- Cheers, Lorenzo