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[195.135.220.15]) by mx.google.com with ESMTPS id n3si2585291edo.15.2019.01.29.05.49.22 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Jan 2019 05:49:22 -0800 (PST) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E4EE7AD5D; Tue, 29 Jan 2019 13:49:21 +0000 (UTC) Date: Tue, 29 Jan 2019 14:49:20 +0100 From: Michal Hocko To: Gerald Schaefer Cc: Mikhail Zaslonko , Mikhail Gavrilov , Andrew Morton , Pavel Tatashin , schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, linux-mm@kvack.org, LKML Subject: Re: [PATCH 0/2] mm, memory_hotplug: fix uninitialized pages fallouts. Message-ID: <20190129134920.GM18811@dhcp22.suse.cz> References: <20190128144506.15603-1-mhocko@kernel.org> <20190129141447.34aa9d0c@thinkpad> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190129141447.34aa9d0c@thinkpad> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Tue 29-01-19 14:14:47, Gerald Schaefer wrote: > 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: Thanks for testing. Can I use you Tested-by? > 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 Yeah, this is c&p mistake on my end. I will use this trace instead. Thanks for spotting. -- Michal Hocko SUSE Labs