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Tue, 15 Oct 2019 18:34:17 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x9FISeTN039074; Tue, 15 Oct 2019 18:34:16 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2vn8enqj4v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 15 Oct 2019 18:34:16 +0000 Received: from abhmp0019.oracle.com (abhmp0019.oracle.com [141.146.116.25]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x9FIYFPU031925; Tue, 15 Oct 2019 18:34:15 GMT Received: from [192.168.1.222] (/71.63.128.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 15 Oct 2019 18:34:14 +0000 Subject: Re: [PATCH v1] hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic() To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Michal Hocko , stable@vger.kernel.org, Anshuman Khandual , Andrew Morton References: <20191015120717.4858-1-david@redhat.com> From: Mike Kravetz Message-ID: <8ac821b6-7575-ab0d-1336-c376a30b8fbb@oracle.com> Date: Tue, 15 Oct 2019 11:34:11 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: <20191015120717.4858-1-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9411 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910150157 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9411 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 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-1910150157 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: On 10/15/19 5:07 AM, David Hildenbrand wrote: > Uninitialized memmaps contain garbage and in the worst case trigger > kernel BUGs, especially with CONFIG_PAGE_POISONING. They should not get > touched. > > Let's make sure that we only consider online memory (managed by the > buddy) that has initialized memmaps. ZONE_DEVICE is not applicable. > > page_zone() will call page_to_nid(), which will trigger > VM_BUG_ON_PGFLAGS(PagePoisoned(page), page) with CONFIG_PAGE_POISONING > and CONFIG_DEBUG_VM_PGFLAGS when called on uninitialized memmaps. This > can be the case when an offline memory block (e.g., never onlined) is > spanned by a zone. > > Note: As explained by Michal in [1], alloc_contig_range() will verify > the range. So it boils down to the wrong access in this function. > > [1] http://lkml.kernel.org/r/20180423000943.GO17484@dhcp22.suse.cz > > Reported-by: Michal Hocko > Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visible after d0dc12e86b319 > Cc: stable@vger.kernel.org # v4.13+ > Cc: Anshuman Khandual > Cc: Mike Kravetz > Cc: Andrew Morton > Cc: Michal Hocko > Signed-off-by: David Hildenbrand Thanks David, Reviewed-by: Mike Kravetz -- Mike Kravetz