From patchwork Wed Aug 2 20:38:10 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Tatashin X-Patchwork-Id: 9877697 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BE77E604D9 for ; Wed, 2 Aug 2017 20:41:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B15B42882A for ; Wed, 2 Aug 2017 20:41:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A64C228836; Wed, 2 Aug 2017 20:41:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.4 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,UNPARSEABLE_RELAY autolearn=no version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C5CFD28835 for ; Wed, 2 Aug 2017 20:41:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Cc:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ML0Y7FBgqoqxbSb17erggZfkuOcEo7qLbr/spnwsEbQ=; b=dKWCWMGH9vjxeE yzqFt73Mlajafa/pepxacfvKbpCso9YaP1QJg/6PycVKhxfKDy4jnHmkRGQQbsGNITzfGQPaMt8ru rwYjCaS02nET8xlpq0yaX5HbteXhGxx19Nanv4N6dUrovN1zUrQEfuXjQWGjL1SytVwptY7Z81eXN il8psGSL0Xs34BAYVubumYMINfoVIlkN0IvrvYP+ehj29ZIZhPGlGQhLbJHRtmhMprwVA7l7cYz9c NF1z9awz08aGQ9reRFPRvuETuIkpl3LqGdKW9cLegX8NAhEr7TEFEQWJgkDZgqY/jGZl8oAyVQ4IB KqCN2C2XDFqea6PU9bhA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dd0RZ-0006K2-F6; Wed, 02 Aug 2017 20:40:37 +0000 Received: from aserp1040.oracle.com ([141.146.126.69]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dd0QS-0003sx-N5 for linux-arm-kernel@lists.infradead.org; Wed, 02 Aug 2017 20:39:30 +0000 Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v72KcURj024796 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 2 Aug 2017 20:38:31 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id v72KcU8v024826 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 2 Aug 2017 20:38:30 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id v72KcTqJ005620; Wed, 2 Aug 2017 20:38:29 GMT Received: from ca-ldom-ol-build-1.us.oracle.com (/10.129.68.23) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 02 Aug 2017 13:38:29 -0700 From: Pavel Tatashin To: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, kasan-dev@googlegroups.com, borntraeger@de.ibm.com, heiko.carstens@de.ibm.com, davem@davemloft.net, willy@infradead.org, mhocko@kernel.org Subject: [v4 01/15] x86/mm: reserve only exiting low pages Date: Wed, 2 Aug 2017 16:38:10 -0400 Message-Id: <1501706304-869240-2-git-send-email-pasha.tatashin@oracle.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1501706304-869240-1-git-send-email-pasha.tatashin@oracle.com> References: <1501706304-869240-1-git-send-email-pasha.tatashin@oracle.com> X-Source-IP: userv0021.oracle.com [156.151.31.71] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170802_133928_911925_D75B13E2 X-CRM114-Status: UNSURE ( 9.30 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Struct pages are initialized by going through __init_single_page(). Since the existing physical memory in memblock is represented in memblock.memory list, struct page for every page from this list goes through __init_single_page(). The second memblock list: memblock.reserved, manages the allocated memory. The memory that won't be available to kernel allocator. So, every page from this list goes through reserve_bootmem_region(), where certain struct page fields are set, the assumption being that the struct pages have been initialized beforehand. In trim_low_memory_range() we unconditionally reserve memoryfrom PFN 0, but memblock.memory might start at a later PFN. For example, in QEMU, e820__memblock_setup() can use PFN 1 as the first PFN in memblock.memory, so PFN 0 is not on memblock.memory (and hence isn't initialized via __init_single_page) but is on memblock.reserved (and hence we set fields in the uninitialized struct page). Currently, the struct page memory is always zeroed during allocation, which prevents this problem from being detected. But, if some asserts provided by CONFIG_DEBUG_VM_PGFLAGS are tighten, this problem may become visible in existing kernels. In this patchset we will stop zeroing struct page memory during allocation. Therefore, this bug must be fixed in order to avoid random assert failures caused by CONFIG_DEBUG_VM_PGFLAGS triggers. The fix is to reserve memory from the first existing PFN. Signed-off-by: Pavel Tatashin Reviewed-by: Steven Sistare Reviewed-by: Daniel Jordan Reviewed-by: Bob Picco --- arch/x86/kernel/setup.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 3486d0498800..489cdc141bcb 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -790,7 +790,10 @@ early_param("reservelow", parse_reservelow); static void __init trim_low_memory_range(void) { - memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); + unsigned long min_pfn = find_min_pfn_with_active_regions(); + phys_addr_t base = min_pfn << PAGE_SHIFT; + + memblock_reserve(base, ALIGN(reserve_low, PAGE_SIZE)); } /*