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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70EFDC64EC7 for ; Thu, 23 Feb 2023 00:06:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F38686B0071; Wed, 22 Feb 2023 19:06:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE7EF6B0072; Wed, 22 Feb 2023 19:06:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D88F26B0073; Wed, 22 Feb 2023 19:06:09 -0500 (EST) 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 C6B796B0071 for ; Wed, 22 Feb 2023 19:06:09 -0500 (EST) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A19B81601C1 for ; Thu, 23 Feb 2023 00:06:09 +0000 (UTC) X-FDA: 80496614058.26.0018811 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf15.hostedemail.com (Postfix) with ESMTP id 9131FA0002 for ; Thu, 23 Feb 2023 00:06:06 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=Y32WBerE; dmarc=none; spf=none (imf15.hostedemail.com: domain of BATV+340b3d9d90e4f578eb11+7123+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+340b3d9d90e4f578eb11+7123+infradead.org+hch@bombadil.srs.infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1677110767; 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=SGz5nzrr6kl9XQ1Pjiut45xDaCZGappO0V2Hw2xCxOo=; b=K7EanGQxS2Zx8ue/MWy1uwTByQwfmxzuoBkjRdenaLO/mUHHOau3WkTNrVj2ZhcMaVf7PS N0W3VDgodEvjhIG3saIw2uiP5TUvwgf80HN3scUMqgOA4Em1VtTncCaHlPkZUCgqEYSZ2p SmgkDuGlVy3Wzk/ZZf8YjET0CG/D6L0= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=bombadil.20210309 header.b=Y32WBerE; dmarc=none; spf=none (imf15.hostedemail.com: domain of BATV+340b3d9d90e4f578eb11+7123+infradead.org+hch@bombadil.srs.infradead.org has no SPF policy when checking 198.137.202.133) smtp.mailfrom=BATV+340b3d9d90e4f578eb11+7123+infradead.org+hch@bombadil.srs.infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1677110767; a=rsa-sha256; cv=none; b=LMg2tGhOvMaVPuWMPvVcciUkBTEvheAVqOGhp+01sa/9dqGtxaaz1Clk+XPpZNjkxgdC2D Q0m3m6ZztegdkZA6V/XuR5FltW4RuYxU+zqqUNd7R6aSxzxYbdCxaik2lF+iIRAi/b4Fke hrv7Vtp7FXmlwQwZHxDhAURxdYdStyg= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=SGz5nzrr6kl9XQ1Pjiut45xDaCZGappO0V2Hw2xCxOo=; b=Y32WBerE9lXfZSywGU2o8Xqhfu B54C6eYhk9WRm6mS49oYuznaXhzjq+W9GbNkfnBFw6Dlsvxra3TmcZ6krBqbr6R+rmZse3gGsc70W atJ36URTU6qbLRw4nbhCl1yBBW+oa5k1S51zib8X0je8tk60pud15Q/Ay9O1jUhWOO5V/TcjPNz6X PdC/gRekMkwnFTvVbRJGmpGlyIJRE6L+OgaKRwmu4mMx2TrxghBaIyk8xVNkcyeA6aKzE6nCvdhUX /UDH22TYGx6LGYGM/2HC3twxSMXDHi8IVScnXquQvTeAqXoFsHkInvrzalhHk45x5ld5F9qfSiYQ1 Xx8uhgvw==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pUz7O-00EVDc-Ts; Thu, 23 Feb 2023 00:05:50 +0000 Date: Wed, 22 Feb 2023 16:05:50 -0800 From: Christoph Hellwig To: Alistair Popple Cc: Jason Gunthorpe , Tejun Heo , Michal Hocko , Yosry Ahmed , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, jhubbard@nvidia.com, tjmercier@google.com, hannes@cmpxchg.org, surenb@google.com, mkoutny@suse.com, daniel@ffwll.ch, "Daniel P . Berrange" , Alex Williamson , Zefan Li , Andrew Morton Subject: Re: [PATCH 14/19] mm: Introduce a cgroup for pinned memory Message-ID: References: <87o7pmnd0p.fsf@nvidia.com> <87k009nvnr.fsf@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87k009nvnr.fsf@nvidia.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Rspamd-Queue-Id: 9131FA0002 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: szkp4nzyotkwxsctaswsfnwhtp45doon X-HE-Tag: 1677110766-179083 X-HE-Meta: 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 YjdUPMYA idU1eZ2vqn4Qn8D8Tl6CA7HC5DMjZWDhmTfEKhPDdrKZ4Z3NddWP0gDoTr9tZ1jytUpwZPEzIGKIKwISPCDJXSeDYsADVvC9hFidMSi04tY8nlhPsj2ByXNaoyxc58xN2bCk63J6bn5OgIRz5/+TS6vvGSs6wXRUEZDP20uXEdJ1jBdLfpB77DBZ4vHjXFXWnGKj2AzOTc2USzTnQ7coXl3r5SwGQDhkOWC/Cfx7Cq3nvc9yYxRmMAfFoGUERuOxirEB/PHhkUYBluBWFWbt5+g3Ue76NNCaM2X9U6Jn0dq6Ppps1JZj5xYbGIdwYdcqOrBn24lAPZpswuLGBWpLCbInNraGkvWzZIEUY59P2N8IAXqA5fMryURrO7vRjDKtQuM7wMIzhN4wt+s5nvYJ0JdODdw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 23, 2023 at 09:59:35AM +1100, Alistair Popple wrote: > The idea was every driver already needs to allocate a pages array to > pass to pin_user_pages(), and by necessity drivers have to keep a > reference to the contents of that in one form or another. So > conceptually the equivalent of: > > struct vm_account { > struct list_head possible_pinners; > struct mem_cgroup *memcg; > struct pages **pages; > [...] > }; > > Unpinnig involves finding a new owner by traversing the list of > page->memcg_data->possible_pinners and iterating over *pages[] to figure > out if that vm_account actually has this page pinned or not and could > own it. > > Agree this is costly though. And I don't think all drivers keep the > array around so "iterating over *pages[]" may need to be a callback. Is pinning in this context referring to FOLL_LONGTERM pins or any FOLL_PIN? In the latter case block based direct I/O does not keep the pages array around, and also is absolutely not willing to pay for the overhead. For FOLL_LONGTERM the schemes sounds vaguely reasonable to me.