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 41255F531CC for ; Mon, 13 Apr 2026 20:35:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9B1596B00B5; Mon, 13 Apr 2026 16:35:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9620E6B00B7; Mon, 13 Apr 2026 16:35:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 89EAD6B00B8; Mon, 13 Apr 2026 16:35:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 7827B6B00B5 for ; Mon, 13 Apr 2026 16:35:38 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 44E1B8B2B0 for ; Mon, 13 Apr 2026 20:35:38 +0000 (UTC) X-FDA: 84654688356.03.E8CF628 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf12.hostedemail.com (Postfix) with ESMTP id A1BF640006 for ; Mon, 13 Apr 2026 20:35:36 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=jf7uu1hT; dmarc=pass (policy=none) header.from=infradead.org; spf=none (imf12.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776112536; 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=HtYokny6y9/Dl1p1xfnv9fH4Sv6CkK/mGZxE/olmdzE=; b=JrhRtmsWGJfgO0ifAzNKEQz2p/7iJ2AHukv6tdxqXhCpqVtGaRqxesefmvR/jMwmFgt7b3 PWH/LAYTzmQVOpT+nvkF7v76NXUdaMWnuxHs5i6reRKWdtV53tEoReUlCgNIsmLQfM5AJ4 HIFYaKJEGXh2hRmlNi1bGvoF1C6nMSU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776112536; a=rsa-sha256; cv=none; b=O5HjtPsG5iKuMVhcrDVmYYGs8QjL3zf0goYG4YDJhcesIteRKszBz2IWWuxNJENQeLTWTg fYy+FXWTNwASyC4UUPtrlEhqCUwsgK+bfzqc2vVFS6PQmlOfIoVdESZAL23Y8VlRNwI0t3 JZM+GfJepaYfCtEGDaEnlcs70kElo2Q= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=jf7uu1hT; dmarc=pass (policy=none) header.from=infradead.org; spf=none (imf12.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=HtYokny6y9/Dl1p1xfnv9fH4Sv6CkK/mGZxE/olmdzE=; b=jf7uu1hTkK2Zwo8KKL/jpCnllm SGc4Da5qY8GmfJl5cU3V0+CgwLIZbm9GlRAVavYLD9l2XG7QmnAQ6BblK7KRgDhDVhh5TP3hWkN0P ThoJDJaT8ngjJZJ5U4jJxKCcX8XvhzGnRDe9hq1OzGE6buVl5zwgfk47IKk3bfIaaSplcJctRSkDP XDc7z14zpX01OvUOxGOQxXNhCDbQuDlJeWDE1iR1eociaVwO6flHBQErkKXTPwghs5XeoQt4gbxK7 Nq+2fhrFzwMOvKha4JhePdOLj5m6F/RyKNjANmNDJ0BqBn8/KpUdcRFaS0bFTDwAumZyyarpLs5PE wvJ4xH+Q==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1wCO0G-0000000EUTe-3j3B; Mon, 13 Apr 2026 20:35:29 +0000 Date: Mon, 13 Apr 2026 21:35:28 +0100 From: Matthew Wilcox To: Zi Yan Cc: Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH 7.2 v2 06/12] mm: fs: remove filemap_nr_thps*() functions and their users Message-ID: References: <20260413192030.3275825-1-ziy@nvidia.com> <20260413192030.3275825-7-ziy@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260413192030.3275825-7-ziy@nvidia.com> X-Rspamd-Queue-Id: A1BF640006 X-Stat-Signature: 34qtmwujh6acspzcxat56pqiqz3z8ice X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1776112536-786691 X-HE-Meta: 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 +17A4yDn fSzaIdkeQDD8xk+IDL6uSXsIRU/oz3Tuj9GEF1bVDXA9+rUuMpOBw1w7DDGBM9K+K3OvKojee9kNskbo+WiXM6yZTHycI8G2vKtln+H5cm0YlnqGceF0Q7Rh99upEtFcnQnM5k891K3VXCnAoBxwFCu7rEGveFwvc60Mv0KdbtcBMQUmZWkfiYNUnpxVbGayPShPDOEq4y+YbB27LYBstfg91xz3gw/Xn/uE15RZURR9omcHGMxkMFCe+cvwEabXOZekzTgBFtnG1wlaOsZBPIgIKp8FslxZRpmBBy5gYzTxIAXF1Yz+KWRznfhkYcG5Jaa8z0LoGgZcALZiaw/iRhqWmWQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 13, 2026 at 03:20:24PM -0400, Zi Yan wrote: > They are used by READ_ONLY_THP_FOR_FS to handle writes to FSes without > large folio support, so that read-only THPs created in these FSes are not > seen by the FSes when the underlying fd becomes writable. Now read-only PMD > THPs only appear in a FS with large folio support and the supported orders > include PMD_ORDRE. > > READ_ONLY_THP_FOR_FS was using mapping->nr_thps, inode->i_writecount, and > smp_mb() to prevent writes to a read-only THP and collapsing writable > folios into a THP. In collapse_file(), mapping->nr_thps is increased, then > smp_mb(), and if inode->i_writecount > 0, collapse is stopped, while > do_dentry_open() first increases inode->i_writecount, then a full memory > fence, and if mapping->nr_thps > 0, all read-only THPs are truncated. > > Now this mechanism can be removed along with READ_ONLY_THP_FOR_FS code, > since a dirty folio check has been added after try_to_unmap() and > try_to_unmap_flush() in collapse_file() to make sure no writable folio can > be collapsed. > > Signed-off-by: Zi Yan > --- > fs/open.c | 27 --------------------------- > include/linux/pagemap.h | 29 ----------------------------- > mm/filemap.c | 1 - > mm/huge_memory.c | 1 - > mm/khugepaged.c | 28 ---------------------------- > 5 files changed, 86 deletions(-) This is great. Reviewed-by: Matthew Wilcox (Oracle)