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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75C1DC433DF for ; Sun, 24 May 2020 07:42:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 06A632078B for ; Sun, 24 May 2020 07:42:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ozaLC5+Z"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="fWl1umd9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 06A632078B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KOceDRYRdt3QmChbOOjIA09LvWppP92Jg6uRpdFb3OU=; b=ozaLC5+Zc24TvH 2H5F8pLUqT9HXWkNcuqv2b6DN5NSrdc0Uo8wtJh4L/gwSaPAJbwXiJuQn1AmVGrPb15c0TES+gbhn fQyAUDsaagG8L91lDYC9mcg6qvr2BAw2346+UayDXhlWz/s4QcoDfru2vqIXkR7rzTJg7BOMK9qOx v8rrZP2lRLvTqQ9z2PeR0QxvgirdmLqJef8NhaDdhYag3fAxXkJ/OYVV6tDJj3qqKwiXed4E/sbUV /WcP3p3uSq+Lh2i+xUntawNuxQV3Dfnj6+U5Bpl9SVHY8dIvlTboW7LWeYa861pfgNJ6/DDfCLL0w 9DgGRYWzDmHOH6oWdBHQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jclHP-0005H9-Gp; Sun, 24 May 2020 07:42:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jclHM-0005GG-TV for linux-arm-kernel@lists.infradead.org; Sun, 24 May 2020 07:42:42 +0000 Received: from kernel.org (unknown [87.71.47.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 26E322076C; Sun, 24 May 2020 07:42:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590306158; bh=+/fFoXXRcAaUgRrF312cHC7kEgpII3DvTDA8eGvdehk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fWl1umd9MDaNFTQL8vtXp9S91lOpXqHQ9cMIrKzvtvJqxr0KCUvLsyHedTsuWhcK+ 8p4N/kJG9k+82H1sIQsHwOKs9c4FXoHV+iXDzQ5Oe5TQpYgYs5FXHs7PZNERJRIt75 vZQkuQA7RKAczl+NpjOLI6H7+2WtBYbABL56OTvw= Date: Sun, 24 May 2020 10:42:30 +0300 From: Mike Rapoport To: Matthew Wilcox Subject: Re: [PATCH 0/7] Record the mm_struct in the page table pages Message-ID: <20200524074230.GM1118872@kernel.org> References: <20200428194449.22615-1-willy@infradead.org> <20200429002624.qkhb362moj6v3vtw@box> <20200429015126.GP29705@bombadil.infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200429015126.GP29705@bombadil.infradead.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200524_004240_976547_AC8626E0 X-CRM114-Status: GOOD ( 16.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , linux-kernel@vger.kernel.org, Russell King , linux-mm@kvack.org, linux-m68k@lists.linux-m68k.org, Geert Uytterhoeven , "Kirill A. Shutemov" , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Apr 28, 2020 at 06:51:26PM -0700, Matthew Wilcox wrote: > On Wed, Apr 29, 2020 at 03:26:24AM +0300, Kirill A. Shutemov wrote: > > On Tue, Apr 28, 2020 at 12:44:42PM -0700, Matthew Wilcox wrote: > > > From: "Matthew Wilcox (Oracle)" > > > > > > Pages which are in use as page tables have some space unused in struct > > > page. It would be handy to have a pointer to the struct mm_struct that > > > they belong to so that we can handle uncorrectable errors in page tables > > > more gracefully. There are a few other things we could use it for too, > > > such as checking that the page table entry actually belongs to the task > > > we think it ought to. This patch series does none of that, but does > > > lay the groundwork for it. > > > > > > Matthew Wilcox (Oracle) (7): > > > > How does it work for kernel side of virtual address space? > > init_mm A note to keep in mind is that most of the kernel page tables are seen as PG_reserved rather than PageTable(). > > And your employer may be interested in semantics around > > CONFIG_ARCH_WANT_HUGE_PMD_SHARE :P > > I was thinking about that. Right now, it's only useful for debugging > purposes (as you point out in a later email). I think it's OK if shared > PMDs aren't supported as well as regular PTEs, just because there are > so few of them that uncorrectable errors are less likely to strike in > those pages. > -- Sincerely yours, Mike. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel