From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 E891BC7619F for ; Mon, 17 Feb 2020 11:21:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B90B4206F4 for ; Mon, 17 Feb 2020 11:21:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B90B4206F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=vega.pgw.jp Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 54BFB6B0006; Mon, 17 Feb 2020 06:21:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4FBF66B0007; Mon, 17 Feb 2020 06:21:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4392B6B0008; Mon, 17 Feb 2020 06:21:39 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0182.hostedemail.com [216.40.44.182]) by kanga.kvack.org (Postfix) with ESMTP id 2C8096B0006 for ; Mon, 17 Feb 2020 06:21:39 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id C440E8248047 for ; Mon, 17 Feb 2020 11:21:38 +0000 (UTC) X-FDA: 76499378676.27.toy56_486da0eea3907 X-HE-Tag: toy56_486da0eea3907 X-Filterd-Recvd-Size: 2072 Received: from auth.gate-on.net (auth.Gate-On.Net [210.197.74.24]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Mon, 17 Feb 2020 11:21:37 +0000 (UTC) Received: from vega.pgw.jp (w0109-49-135-103-152.uqwimax.jp [49.135.103.152]) by auth.gate-on.net (Postfix) with ESMTP id 7B282C2665; Mon, 17 Feb 2020 20:21:33 +0900 (JST) Received: from localhost (vega.pgw.jp [10.5.0.30]) by vega.pgw.jp (Postfix) with SMTP id 19A37A53D; Mon, 17 Feb 2020 20:21:32 +0900 (JST) From: Content-Type: text/plain; charset=ISO-2022-JP To: mhocko@kernel.org Cc: bhe@redhat.com, bugzilla-daemon@bugzilla.kernel.org, akpm@linux-foundation.org, richardw.yang@linux.intel.com, david@redhat.com, n-horiguchi@ah.jp.nec.com, linux-mm@kvack.org, kkabe@vega.pgw.jp Subject: Re: [Bug 206401] kernel panic on Hyper-V after 5 minutes due to memory hot-add In-Reply-To: Your message of "Mon, 17 Feb 2020 11:33:35 +0100". <20200217103335.GI31531@dhcp22.suse.cz> X-Mailer: mnews [version 1.22PL5] 2002-11-27(Wed) Date: Mon, 17 Feb 2020 20:21:32 +0900 Message-ID: <200217202132.M0113661@vega.pgw.jp> 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: mhocko@kernel.org sed in <20200217103335.GI31531@dhcp22.suse.cz> >> On Fri 14-02-20 23:26:29, kkabe@vega.pgw.jp wrote: >> [...] >> > [root@localhost ~]# [ 302.391125] hv_balloon: Max. dynamic memory size: 1048576 MB >> >> Is this saying that the system might hotplug up to 1TB of memory on this >> 32b system? Probably. Hypervisor API uses 64-bit values, so that's why I added add_memory() printk to see if it's overflowing 4GB. I guessed drivers/hv/hv_balloon.c:hv_mem_hot_add() needs a check to not hot-add over 4GB memory on non-PAE systems and so on, but that's another story. >> Btw. the hotplug support on highmem systems is quite likely to be broken >> and/or full of corner cases. I seriously doubt this is something anybody >> should be running in production without a _lot_ of work. >> >> Is there any real usecase to run HyperV hotplug on 32b system? >> -- >> Michal Hocko >> SUSE Labs