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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 23 Apr 2019 14:36:58 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3NDav3t34668690 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 23 Apr 2019 13:36:57 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD4134204D; Tue, 23 Apr 2019 13:36:57 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 03C0142047; Tue, 23 Apr 2019 13:36:57 +0000 (GMT) Received: from [9.145.7.116] (unknown [9.145.7.116]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 23 Apr 2019 13:36:56 +0000 (GMT) Subject: bos To: Thomas Gleixner Cc: Michael Ellerman , Dave Hansen , LKML , rguenther@suse.de, mhocko@suse.com, vbabka@suse.cz, luto@amacapital.net, x86@kernel.org, Andrew Morton , linux-mm@kvack.org, stable@vger.kernel.org References: <20190401141549.3F4721FE@viggo.jf.intel.com> <87d0lht1c0.fsf@concordia.ellerman.id.au> <6718ede2-1fcb-1a8f-a116-250eef6416c7@linux.vnet.ibm.com> From: Laurent Dufour Date: Tue, 23 Apr 2019 15:36:56 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19042313-0008-0000-0000-000002DCBE43 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042313-0009-0000-0000-000022490F58 Message-Id: <4791a72f-901c-59cb-0553-5c32e26423f7@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-23_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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=8.0.1-1810050000 definitions=main-1904230092 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: Le 23/04/2019 à 15:34, Thomas Gleixner a écrit : > On Tue, 23 Apr 2019, Laurent Dufour wrote: >> Le 20/04/2019 à 12:31, Michael Ellerman a écrit : >>> Thomas Gleixner writes: >>>> Aside of that the powerpc variant looks suspicious: >>>> >>>> static inline void arch_unmap(struct mm_struct *mm, >>>> unsigned long start, unsigned long end) >>>> { >>>> if (start <= mm->context.vdso_base && mm->context.vdso_base < end) >>>> mm->context.vdso_base = 0; >>>> } >>>> >>>> Shouldn't that be: >>>> >>>> if (start >= mm->context.vdso_base && mm->context.vdso_base < end) >>>> >>>> Hmm? >>> >>> Yeah looks pretty suspicious. I'll follow-up with Laurent who wrote it. >>> Thanks for spotting it! >> >> I've to admit that I had to read that code carefully before answering. >> >> There are 2 assumptions here: >> 1. 'start' and 'end' are page aligned (this is guaranteed by __do_munmap(). >> 2. the VDSO is 1 page (this is guaranteed by the union vdso_data_store on >> powerpc). >> >> The idea is to handle a munmap() call surrounding the VDSO area: >> | VDSO | >> ^start ^end >> >> This is covered by this test, as the munmap() matching the exact boundaries of >> the VDSO is handled too. >> >> Am I missing something ? > > Well if this is the intention, then you missed to add a comment explaining it :) > > Thanks, > > tglx You're right, and I was thinking the same when I read that code this morning ;) I'll propose a patch to a add an explicit comment. Thanks, Laurent.