From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=xS+q=XN=lists.ozlabs.org=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@kernel.org>
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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2
	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 208BEC4CEC9
	for <linuxppc-dev@archiver.kernel.org>; Wed, 18 Sep 2019 18:25:36 +0000 (UTC)
Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2])
	(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 47DD221848
	for <linuxppc-dev@archiver.kernel.org>; Wed, 18 Sep 2019 18:25:35 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47DD221848
Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=de.ibm.com
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])
	by lists.ozlabs.org (Postfix) with ESMTP id 46YT1S3mZvzF4DZ
	for <linuxppc-dev@archiver.kernel.org>; Thu, 19 Sep 2019 04:25:32 +1000 (AEST)
Authentication-Results: lists.ozlabs.org;
 spf=pass (mailfrom) smtp.mailfrom=de.ibm.com
 (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com;
 envelope-from=gerald.schaefer@de.ibm.com; receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org;
 dmarc=none (p=none dis=none) header.from=de.ibm.com
Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com
 [148.163.158.5])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 46YSyb72DvzF4hl
 for <linuxppc-dev@lists.ozlabs.org>; Thu, 19 Sep 2019 04:23:02 +1000 (AEST)
Received: from pps.filterd (m0127361.ppops.net [127.0.0.1])
 by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id
 x8IIML9S171143
 for <linuxppc-dev@lists.ozlabs.org>; Wed, 18 Sep 2019 14:23:00 -0400
Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98])
 by mx0a-001b2d01.pphosted.com with ESMTP id 2v39pf3ww3-1
 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT)
 for <linuxppc-dev@lists.ozlabs.org>; Wed, 18 Sep 2019 14:22:59 -0400
Received: from localhost
 by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only!
 Violators will be prosecuted
 for <linuxppc-dev@lists.ozlabs.org> from <gerald.schaefer@de.ibm.com>;
 Wed, 18 Sep 2019 19:22:57 +0100
Received: from b06avi18878370.portsmouth.uk.ibm.com (9.149.26.194)
 by e06smtp02.uk.ibm.com (192.168.101.132) with IBM ESMTP SMTP Gateway:
 Authorized Use Only! Violators will be prosecuted; 
 (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256)
 Wed, 18 Sep 2019 19:22:47 +0100
Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com
 [9.149.105.61])
 by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP
 id x8IIMkOY40436054
 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK);
 Wed, 18 Sep 2019 18:22:46 GMT
Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1])
 by IMSVA (Postfix) with ESMTP id 4D57D11C058;
 Wed, 18 Sep 2019 18:22:46 +0000 (GMT)
Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1])
 by IMSVA (Postfix) with ESMTP id 02F0511C04A;
 Wed, 18 Sep 2019 18:22:45 +0000 (GMT)
Received: from thinkpad (unknown [9.152.212.222])
 by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP;
 Wed, 18 Sep 2019 18:22:44 +0000 (GMT)
Date: Wed, 18 Sep 2019 20:22:43 +0200
From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Subject: Re: [PATCH V2 2/2] mm/pgtable/debug: Add test validating
 architecture page table helpers
In-Reply-To: <64504101-d9dd-f273-02f9-e9a8b178eecc@c-s.fr>
References: <1568268173-31302-1-git-send-email-anshuman.khandual@arm.com>
 <1568268173-31302-3-git-send-email-anshuman.khandual@arm.com>
 <ab0ca38b-1e4f-b636-f8b4-007a15903984@c-s.fr>
 <502c497a-9bf1-7d2e-95f2-cfebcd9cf1d9@arm.com>
 <95ed9d92-dd43-4c45-2e52-738aed7f2fb5@c-s.fr>
 <f872e6f4-a5cb-069d-2034-78961930cb9f@arm.com>
 <64504101-d9dd-f273-02f9-e9a8b178eecc@c-s.fr>
X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-TM-AS-GCONF: 00
x-cbid: 19091818-0008-0000-0000-000003180C76
X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused
x-cbparentid: 19091818-0009-0000-0000-00004A368EF9
Message-Id: <20190918202243.37e709df@thinkpad>
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, ,
 definitions=2019-09-18_09:, , signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0
 priorityscore=1501
 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0
 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0
 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx
 scancount=1 engine=8.0.1-1908290000 definitions=main-1909180162
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: Mark Rutland <mark.rutland@arm.com>, linux-ia64@vger.kernel.org,
 linux-sh@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
 James Hogan <jhogan@kernel.org>,
 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
 Heiko Carstens <heiko.carstens@de.ibm.com>, Michal Hocko <mhocko@kernel.org>,
 linux-mm@kvack.org, Paul Mackerras <paulus@samba.org>,
 sparclinux@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
 linux-s390@vger.kernel.org, x86@kernel.org,
 Russell King - ARM Linux <linux@armlinux.org.uk>,
 Matthew Wilcox <willy@infradead.org>, Steven Price <Steven.Price@arm.com>,
 Jason Gunthorpe <jgg@ziepe.ca>, linux-arm-kernel@lists.infradead.org,
 linux-snps-arc@lists.infradead.org, Kees Cook <keescook@chromium.org>,
 Anshuman Khandual <anshuman.khandual@arm.com>,
 Masahiro Yamada <yamada.masahiro@socionext.com>,
 Mark Brown <broonie@kernel.org>, "Kirill A . Shutemov" <kirill@shutemov.name>,
 Dan Williams <dan.j.williams@intel.com>, Vlastimil Babka <vbabka@suse.cz>,
 Sri Krishna chowdary <schowdary@nvidia.com>,
 Ard Biesheuvel <ard.biesheuvel@linaro.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
 Dave Hansen <dave.hansen@intel.com>, linux-mips@vger.kernel.org,
 Ralf Baechle <ralf@linux-mips.org>, linux-kernel@vger.kernel.org,
 Paul Burton <paul.burton@mips.com>, Mike Rapoport <rppt@linux.vnet.ibm.com>,
 Vineet Gupta <vgupta@synopsys.com>,
 Martin Schwidefsky <schwidefsky@de.ibm.com>,
 Andrew Morton <akpm@linux-foundation.org>, linuxppc-dev@lists.ozlabs.org,
 "David S. Miller" <davem@davemloft.net>
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On Wed, 18 Sep 2019 18:26:03 +0200
Christophe Leroy <christophe.leroy@c-s.fr> wrote:

[..] 
> My suggestion was not to completely drop the #ifdef but to do like you 
> did in pgd_clear_tests() for instance, ie to add the following test on 
> top of the function:
> 
> 	if (mm_pud_folded(mm) || is_defined(__ARCH_HAS_5LEVEL_HACK))
> 		return;
> 

Ah, very nice, this would also fix the remaining issues for s390. Since
we have dynamic page table folding, neither __PAGETABLE_PXX_FOLDED nor
__ARCH_HAS_XLEVEL_HACK is defined, but mm_pxx_folded() will work.

mm_alloc() returns with a 3-level page table by default on s390, so we
will run into issues in p4d_clear/populate_tests(), and also at the end
with p4d/pud_free() (double free).

So, adding the mm_pud_folded() check to p4d_clear/populate_tests(),
and also adding mm_p4d/pud_folded() checks at the end before calling
p4d/pud_free(), would make it all work on s390.

BTW, regarding p4d/pud_free(), I'm not sure if we should rather check
the folding inside our s390 functions, similar to how we do it for
p4d/pud_free_tlb(), instead of relying on not being called for folded
p4d/pud. So far, I see no problem with this behavior, all callers of
p4d/pud_free() should be fine because of our folding check within
p4d/pud_present/none(). But that doesn't mean that it is correct not
to check for the folding inside p4d/pud_free(). At least, with this
test module we do now have a caller of p4d/pud_free() on potentially
folded entries, so instead of adding pxx_folded() checks to this
test module, we could add them to our p4d/pud_free() functions.
Any thoughts on this?

Regards,
Gerald