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=-8.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 8FCEBC49ED7 for ; Fri, 13 Sep 2019 08:51:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E6D6208C0 for ; Fri, 13 Sep 2019 08:51:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="M6Wl/quw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387635AbfIMIvi (ORCPT ); Fri, 13 Sep 2019 04:51:38 -0400 Received: from mail-ed1-f65.google.com ([209.85.208.65]:37095 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387499AbfIMIvi (ORCPT ); Fri, 13 Sep 2019 04:51:38 -0400 Received: by mail-ed1-f65.google.com with SMTP id i1so26404830edv.4 for ; Fri, 13 Sep 2019 01:51:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=ljRy//1oqpxbNqcuLvCNHWlNadtkzDq51hCzmFakYzM=; b=M6Wl/quwPsEOiMFNCv3xSOrdnDulq5fkBOVf8YSY3tiw77PxkkHJwmP5iEk0kohLlY pg4uPVtKpUEevoagc8enKn4uPrSlBiZORCgQoAOniX52xYmOZkzG1/HzuVuRwG1eo1oP UUMYm6uVKM/ZyICPXIY6dw0BD4t6sF6ZjlwPzQZa+ZeBzMMqOs4xYJXwzCpcBNDo8jhx jXjUL9kfKg583djOtcu64hthdRWYl9M2FSJHI0vB9ZCDV10OZHe+j1P2FdlMaHZTn/Du o7aK3kotbpwDLHIjGD7A7LXZ8OC4HcGT0NeYVB7fDkav49RWCtmQCPySSqquXilUNVHm pP3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to:user-agent; bh=ljRy//1oqpxbNqcuLvCNHWlNadtkzDq51hCzmFakYzM=; b=OgEb52QDZKE1/hiGnmoMzf2kWX2QbKOGRvKtvSdveUCUgB14Ha1o411yVMIKkBG3Sw TVhLpo6isLjN8PfXlfcr5HgGmnZTEtOXbV0guFAuAPfLOdtYt2FHDBT6MZMER08f1cjE x8yStwAQP6rYA5b0Cvl2zepv/bYQbOK8ZIktUAmfSbWSbz9SL65MFHmICinboypS/ypI 6PVPnasHXvju88hNrZqKYEYNjYyR3qmMMUFuztZhP3lnLf2/0WG73xhIsBxzDbiBabkd zbi/FUSrM5vb6AX9PqC2GXeSFObgHhbnAdUG2e/JNX5BR35PHj39XgtZWgCfW3g67ehC yjgg== X-Gm-Message-State: APjAAAUeRo6en9Z9MPPCrE2mbAI4RRJHAPWw2tpu9D+WHecoY8ADzKP9 eWwIV5gMJiLSjbq3eDdNFJljDdoVfcYtOg== X-Google-Smtp-Source: APXvYqxZm96QADm/8SST6BnmvoIUqtDzA7VCb5AHjQ8XsG2pGy1aWbbiVHhIwmyiU7DjVjOntMuCeQ== X-Received: by 2002:a50:ee92:: with SMTP id f18mr24791178edr.253.1568364694523; Fri, 13 Sep 2019 01:51:34 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id j30sm5287480edb.8.2019.09.13.01.51.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 13 Sep 2019 01:51:33 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id A972310160B; Fri, 13 Sep 2019 11:51:35 +0300 (+03) Date: Fri, 13 Sep 2019 11:51:35 +0300 From: "Kirill A. Shutemov" To: Anshuman Khandual Cc: Christophe Leroy , linux-mm@kvack.org, Mark Rutland , linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, Peter Zijlstra , James Hogan , Heiko Carstens , Michal Hocko , Dave Hansen , Paul Mackerras , sparclinux@vger.kernel.org, Dan Williams , linux-s390@vger.kernel.org, Jason Gunthorpe , x86@kernel.org, Russell King - ARM Linux , Matthew Wilcox , Steven Price , Tetsuo Handa , Vlastimil Babka , linux-snps-arc@lists.infradead.org, Kees Cook , Mark Brown , Thomas Gleixner , Gerald Schaefer , linux-arm-kernel@lists.infradead.org, Sri Krishna chowdary , Masahiro Yamada , Greg Kroah-Hartman , Ard Biesheuvel , 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" Subject: Re: [PATCH] mm/pgtable/debug: Fix test validating architecture page table helpers Message-ID: <20190913085135.rfr3zrabghi2qo2t@box> References: <1892b37d1fd9a4ed39e76c4b999b6556077201c0.1568355752.git.christophe.leroy@c-s.fr> <527dd29d-45fa-4d83-1899-6cbf268dd749@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Fri, Sep 13, 2019 at 02:12:45PM +0530, Anshuman Khandual wrote: > > > On 09/13/2019 12:41 PM, Christophe Leroy wrote: > > > > > > Le 13/09/2019 à 09:03, Christophe Leroy a écrit : > >> > >> > >> Le 13/09/2019 à 08:58, Anshuman Khandual a écrit : > >>> On 09/13/2019 11:53 AM, Christophe Leroy wrote: > >>>> Fix build failure on powerpc. > >>>> > >>>> Fix preemption imbalance. > >>>> > >>>> Signed-off-by: Christophe Leroy > >>>> --- > >>>>   mm/arch_pgtable_test.c | 3 +++ > >>>>   1 file changed, 3 insertions(+) > >>>> > >>>> diff --git a/mm/arch_pgtable_test.c b/mm/arch_pgtable_test.c > >>>> index 8b4a92756ad8..f2b3c9ec35fa 100644 > >>>> --- a/mm/arch_pgtable_test.c > >>>> +++ b/mm/arch_pgtable_test.c > >>>> @@ -24,6 +24,7 @@ > >>>>   #include > >>>>   #include > >>>>   #include > >>>> +#include > >>> > >>> This is okay. > >>> > >>>>   #include > >>>>   #include > >>>> @@ -400,6 +401,8 @@ static int __init arch_pgtable_tests_init(void) > >>>>       p4d_clear_tests(p4dp); > >>>>       pgd_clear_tests(mm, pgdp); > >>>> +    pte_unmap(ptep); > >>>> + > >>> > >>> Now the preemption imbalance via pte_alloc_map() path i.e > >>> > >>> pte_alloc_map() -> pte_offset_map() -> kmap_atomic() > >>> > >>> Is not this very much powerpc 32 specific or this will be applicable > >>> for all platform which uses kmap_XXX() to map high memory ? > >>> > >> > >> See https://elixir.bootlin.com/linux/v5.3-rc8/source/include/linux/highmem.h#L91 > >> > >> I think it applies at least to all arches using the generic implementation. > >> > >> Applies also to arm: > >> https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/mm/highmem.c#L52 > >> > >> Applies also to mips: > >> https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/mips/mm/highmem.c#L47 > >> > >> Same on sparc: > >> https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/sparc/mm/highmem.c#L52 > >> > >> Same on x86: > >> https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/x86/mm/highmem_32.c#L34 > >> > >> I have not checked others, but I guess it is like that for all. > >> > > > > > > Seems like I answered too quickly. All kmap_atomic() do preempt_disable(), but not all pte_alloc_map() call kmap_atomic(). > > > > However, for instance ARM does: > > > > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/include/asm/pgtable.h#L200 > > > > And X86 as well: > > > > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/x86/include/asm/pgtable_32.h#L51 > > > > Microblaze also: > > > > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/microblaze/include/asm/pgtable.h#L495 > > All the above platforms checks out to be using k[un]map_atomic(). I am wondering whether > any of the intermediate levels will have similar problems on any these 32 bit platforms > or any other platforms which might be using generic k[un]map_atomic(). No. Kernel only allocates pte page table from highmem. All other page tables are always visible in kernel address space. -- Kirill A. Shutemov