From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 152842B2D7; Tue, 25 Aug 2026 19:16:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787685375; cv=none; b=o8EQfgI7yeFdAjksQ1niD6zjZ6INVCTqocKA36b22N3TI7PI3BEPQoojvBdvIyf+I5nDqUoPpuMcSiq4KCCW+d4IqDevu+CdJZcit26XQtzkK8hr3UCJOVnc8+a/3Xb8hgaj5o5thKzzrnteciAF7MmZyHBM7zJP6mHV6vVkJjA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787685375; c=relaxed/simple; bh=rXtS4lqKXv5+XHu4i78YlqMyRuGgxSA34Z6hgz1wqN8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ew3HsLqM3b3TOB1jTOrTna6HaZvdopL49glo3aJE/XQGWiAIX22cRCu0t9qcevR3USuBD9NlXDOY+bDQilxttqv7T4bvOtHLdTqd56jVewmddTh2LBaKJpgKVXVC/JaOQZZZ2LnUpochOZ07zz0QsoP4GxxAdmnpdTOCdLBIiMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=G09TgWUe; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="G09TgWUe" 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=ycXANbtGC0cUw84iuY50XDEeCaFMT6BdiIVSuYymPl8=; b=G09TgWUeIwSs4vxXpNMyxpfWFu 2vfuSKgft3JGN5DgcxEAP8qFTNiz5/q1nWpCVeG+nk/0vQFq7MTEXSrAhrlMKp5xnLlcGWBXm3ASp J/MD/QHCyS3Zql66PM6J0c1v65m5lQWwOI6xmq/vs1ECTRmGMpaGVBuetOkRG5gEAUpc1HDSp5n1Q fHu1OIqCVnFidu6LDjAM48gUzdzOXVY65VQWr4zQ250pcAgKsVdkC2hExrCPKcSKtQSOqKx4FqP86 FCTZr1gq6bfKLYRlJgkgMA/t61T4tlKRoFa71LU3P6aue9NcBTQbSGDGNcpVlw0bo1gUCQ5XHqc09 TCV+qAZg==; Received: from willy by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wywcw-00000009aXy-02wf; Tue, 25 Aug 2026 19:16:06 +0000 Date: Tue, 25 Aug 2026 20:16:05 +0100 From: Matthew Wilcox To: David Howells Cc: Pedro Falcato , Christoph Hellwig , Jann Horn , John Hubbard , Jan Kara , Rik van Riel , Qu Wenruo , "Darrick J. Wong" , linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org Subject: Re: Removing ->dirty_folio Message-ID: References: <798622.1787640486@warthog.procyon.org.uk> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <798622.1787640486@warthog.procyon.org.uk> On Tue, Aug 25, 2026 at 07:48:06AM +0100, David Howells wrote: > Matthew Wilcox wrote: > > > I'm probably missing some stuff here. Let me know. > > mmap()? That usually tosses a spanner in somewhere. Well, you have to have mmap()ed a file for GUP to be able to happen. And it has to be shared writable for us to care about writeback. The nice thing about GUP is that it goes through the normal fault handler path. The nasty thing about GUP is that we don't have a way to revoke a GUP access to that page like we do through page tables. >