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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 219EFC433FF for ; Fri, 9 Aug 2019 13:52:19 +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 E4DA72171F for ; Fri, 9 Aug 2019 13:52:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tyeapJ1h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E4DA72171F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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=gNpg3+mYuRQxFD4KjXdAZjKcAB+Ecyj9n86JTC5lqR8=; b=tyeapJ1h9/CNyS w+pqqlR45K/aMP8YJQJpcvZ9uHC5kjZ7IcU6OgNpunTIkZupJosxxb9e3MeqKAGnwyV9InghsBH8E qmxBtSmbzwcYNsdwWBh8T1BMZILA6a31cHJIvrNbqi/QoiDYcY7gzfLFExqwZGo9oUFMbRb7eBPmv u7PikC2KFazXQXy1w2StMMee+HorQqIIDCKnqkFIePGJ9qFsEii+6Ro3M7bwWM9sQDaKQNAYzebnx hpw16R+Zs/GPfz/bW7MJr/hUnpb+9D80GnYKom2fgHcKhdDot+U7+FvmQU7U/fk1flnA+FvviDpUU lNW5P+aGHWoPnVxehSlw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hw5JR-0002QC-Ji; Fri, 09 Aug 2019 13:52:09 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hw5JK-0002PQ-U7; Fri, 09 Aug 2019 13:52:02 +0000 Date: Fri, 9 Aug 2019 06:52:02 -0700 From: Matthew Wilcox To: Anshuman Khandual Subject: Re: [RFC V2 0/1] mm/debug: Add tests for architecture exported page table helpers Message-ID: <20190809135202.GN5482@bombadil.infradead.org> References: <1565335998-22553-1-git-send-email-anshuman.khandual@arm.com> <20190809101632.GM5482@bombadil.infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) 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: Mark Rutland , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , James Hogan , Tetsuo Handa , Heiko Carstens , Michal Hocko , linux-mm@kvack.org, Dave Hansen , Paul Mackerras , sparclinux@vger.kernel.org, Thomas Gleixner , linux-s390@vger.kernel.org, Michael Ellerman , x86@kernel.org, Russell King - ARM Linux , Steven Price , Jason Gunthorpe , linux-arm-kernel@lists.infradead.org, linux-snps-arc@lists.infradead.org, Kees Cook , Masahiro Yamada , Mark Brown , Dan Williams , Vlastimil Babka , Sri Krishna chowdary , Ard Biesheuvel , Greg Kroah-Hartman , linux-mips@vger.kernel.org, Ralf Baechle , linux-kernel@vger.kernel.org, Paul Burton , Mike Rapoport , Vineet Gupta , Martin Schwidefsky , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" 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 Fri, Aug 09, 2019 at 04:05:07PM +0530, Anshuman Khandual wrote: > On 08/09/2019 03:46 PM, Matthew Wilcox wrote: > > On Fri, Aug 09, 2019 at 01:03:17PM +0530, Anshuman Khandual wrote: > >> Should alloc_gigantic_page() be made available as an interface for general > >> use in the kernel. The test module here uses very similar implementation from > >> HugeTLB to allocate a PUD aligned memory block. Similar for mm_alloc() which > >> needs to be exported through a header. > > > > Why are you allocating memory at all instead of just using some > > known-to-exist PFNs like I suggested? > > We needed PFN to be PUD aligned for pfn_pud() and PMD aligned for mk_pmd(). > Now walking the kernel page table for a known symbol like kernel_init() I didn't say to walk the kernel page table. I said to call virt_to_pfn() for a known symbol like kernel_init(). > as you had suggested earlier we might encounter page table page entries at PMD > and PUD which might not be PMD or PUD aligned respectively. It seemed to me > that alignment requirement is applicable only for mk_pmd() and pfn_pud() > which create large mappings at those levels but that requirement does not > exist for page table pages pointing to next level. Is not that correct ? Or > I am missing something here ? Just clear the bottom bits off the PFN until you get a PMD or PUD aligned PFN. It's really not hard. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel