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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 29 Jan 2019 13:14:51 -0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x0TDEoFl61735050 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 29 Jan 2019 13:14:50 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 58B3B42047; Tue, 29 Jan 2019 13:14:50 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F28C04204D; Tue, 29 Jan 2019 13:14:49 +0000 (GMT) Received: from thinkpad (unknown [9.152.99.81]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 29 Jan 2019 13:14:49 +0000 (GMT) Date: Tue, 29 Jan 2019 14:14:47 +0100 From: Gerald Schaefer To: Michal Hocko Cc: Mikhail Zaslonko , Mikhail Gavrilov , Andrew Morton , Pavel Tatashin , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, , LKML Subject: Re: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts. In-Reply-To: <20190128144506.15603-1-mhocko@kernel.org> References: <20190128144506.15603-1-mhocko@kernel.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 19012913-0008-0000-0000-000002B775A7 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19012913-0009-0000-0000-00002223B856 Message-Id: <20190129141447.34aa9d0c@thinkpad> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-29_10:,, 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-1901290099 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 Mon, 28 Jan 2019 15:45:04 +0100 Michal Hocko wrote: > Hi, > Mikhail has posted fixes for the two bugs quite some time ago [1]. I > have pushed back on those fixes because I believed that it is much > better to plug the problem at the initialization time rather than play > whack-a-mole all over the hotplug code and find all the places which > expect the full memory section to be initialized. We have ended up with > 2830bf6f05fb ("mm, memory_hotplug: initialize struct pages for the full > memory section") merged and cause a regression [2][3]. The reason is > that there might be memory layouts when two NUMA nodes share the same > memory section so the merged fix is simply incorrect. > > In order to plug this hole we really have to be zone range aware in > those handlers. I have split up the original patch into two. One is > unchanged (patch 2) and I took a different approach for `removable' > crash. It would be great if Mikhail could test it still works for his > memory layout. > > [1] http://lkml.kernel.org/r/20181105150401.97287-2-zaslonko@linux.ibm.com > [2] https://bugzilla.redhat.com/show_bug.cgi?id=1666948 > [3] http://lkml.kernel.org/r/20190125163938.GA20411@dhcp22.suse.cz I verified that both patches fix the issues we had with valid_zones (with mem=2050M) and removable (with mem=3075M). However, the call trace in the description of your patch 1 is wrong. You basically have the same call trace for test_pages_in_a_zone in both patches. The "removable" patch should have the call trace for is_mem_section_removable from Mikhails original patches: CONFIG_DEBUG_VM_PGFLAGS=y kernel parameter mem=3075M -------------------------- page:000003d08300c000 is uninitialized and poisoned page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) Call Trace: ([<000000000038596c>] is_mem_section_removable+0xb4/0x190) [<00000000008f12fa>] show_mem_removable+0x9a/0xd8 [<00000000008cf9c4>] dev_attr_show+0x34/0x70 [<0000000000463ad0>] sysfs_kf_seq_show+0xc8/0x148 [<00000000003e4194>] seq_read+0x204/0x480 [<00000000003b53ea>] __vfs_read+0x32/0x178 [<00000000003b55b2>] vfs_read+0x82/0x138 [<00000000003b5be2>] ksys_read+0x5a/0xb0 [<0000000000b86ba0>] system_call+0xdc/0x2d8 Last Breaking-Event-Address: [<000000000038596c>] is_mem_section_removable+0xb4/0x190 Kernel panic - not syncing: Fatal exception: panic_on_oops