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=-8.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 64D9EC4CECE for ; Mon, 14 Oct 2019 13:29:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 34A5921835 for ; Mon, 14 Oct 2019 13:29:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 34A5921835 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D1B5B8E0006; Mon, 14 Oct 2019 09:29:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CCB668E0005; Mon, 14 Oct 2019 09:29:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BB9AF8E0006; Mon, 14 Oct 2019 09:29:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id 9B1098E0005 for ; Mon, 14 Oct 2019 09:29:07 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 2A4F582DDBC1 for ; Mon, 14 Oct 2019 13:29:07 +0000 (UTC) X-FDA: 76042471134.01.test84_6cabdfb69b810 X-HE-Tag: test84_6cabdfb69b810 X-Filterd-Recvd-Size: 3081 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Mon, 14 Oct 2019 13:29:06 +0000 (UTC) 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 D696BBABC; Mon, 14 Oct 2019 13:29:04 +0000 (UTC) Date: Mon, 14 Oct 2019 15:29:04 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton Subject: Re: [PATCH v1] drivers/base/memory.c: Don't access uninitialized memmaps in soft_offline_page_store() Message-ID: <20191014132904.GI317@dhcp22.suse.cz> References: <20191010141200.8985-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191010141200.8985-1-david@redhat.com> 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 Thu 10-10-19 16:12:00, 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. > > Right now, when trying to soft-offline a PFN that resides on a memory > block that was never onlined, one gets a misleading error with > CONFIG_PAGE_POISONING: > :/# echo 5637144576 > /sys/devices/system/memory/soft_offline_page > [ 23.097167] soft offline: 0x150000 page already poisoned > > But the actual result depends on the garbage in the memmap. > > soft_offline_page() can only work with online pages, it returns -EIO in > case of ZONE_DEVICE. Make sure to only forward pages that are online > (iow, managed by the buddy) and, therefore, have an initialized memmap. > > Add a check against pfn_to_online_page() and similarly return -EIO. > > Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") # visible after d0dc12e86b319 > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Cc: Michal Hocko > Cc: Andrew Morton > Signed-off-by: David Hildenbrand Acked-by: Michal Hocko > --- > drivers/base/memory.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/base/memory.c b/drivers/base/memory.c > index 6bea4f3f8040..55907c27075b 100644 > --- a/drivers/base/memory.c > +++ b/drivers/base/memory.c > @@ -540,6 +540,9 @@ static ssize_t soft_offline_page_store(struct device *dev, > pfn >>= PAGE_SHIFT; > if (!pfn_valid(pfn)) > return -ENXIO; > + /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */ > + if (!pfn_to_online_page(pfn)) > + return -EIO; > ret = soft_offline_page(pfn_to_page(pfn), 0); > return ret == 0 ? count : ret; > } > -- > 2.21.0 -- Michal Hocko SUSE Labs