From patchwork Mon Aug 7 20:38:35 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Tatashin X-Patchwork-Id: 9886201 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 5B49F603B4 for ; Mon, 7 Aug 2017 21:02:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4B4E528676 for ; Mon, 7 Aug 2017 21:02:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3D93428681; Mon, 7 Aug 2017 21:02:58 +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=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, RCVD_IN_DNSWL_NONE, UNPARSEABLE_RELAY autolearn=unavailable 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 4052E28676 for ; Mon, 7 Aug 2017 21:02:57 +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=q3i3YbjaPrNjd3sgzma0vcxS3vgvBHyCYFCa5qIaxI0=; b=JOT2IQJL4TtQJT l9kWcbcAQh1p5xi0ZNjhroNEMJoWDUV1yZ3AKo4Jpudyp1zv4fRuWMNAJWksugR/hSCsQgay5F3qn dfMEa9V/eBiCfabiVwKw5ylZvZYJzZI+7JaPPKRvxlU5cICNDpc3ttNc/9vTwFsoW2mKC1v+gJneg Ulg+vW68gqL3Mv+osvkAAeYn/n6U1Uw1Aw9N3xDEuLiT+nLSX62qcqasB5ltMViGOlgvCJ7iSJ3MR Oq6CptNrYRmGEaBL7YcoJod/lq8LF+lJurIHDQKwBe6s3Jx++qa1dgMdImH2qtJcqSD0PN8lk6kNy 1z5NuV738ZTiYjtmEHyw==; 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 1depAi-000354-L5; Mon, 07 Aug 2017 21:02:44 +0000 Received: from userp1040.oracle.com ([156.151.31.81]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1deoor-00044i-S9 for linux-arm-kernel@lists.infradead.org; Mon, 07 Aug 2017 20:40:20 +0000 Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v77KcuVp030719 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 7 Aug 2017 20:38:57 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id v77KctmG031883 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 7 Aug 2017 20:38:56 GMT Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id v77Kcs6k020852; Mon, 7 Aug 2017 20:38:54 GMT Received: from ca-ldom-ol-build-1.us.oracle.com (/10.129.68.23) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 07 Aug 2017 13:38:54 -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, ard.biesheuvel@linaro.org, will.deacon@arm.com, catalin.marinas@arm.com, sam@ravnborg.org Subject: [v6 01/15] x86/mm: reserve only exiting low pages Date: Mon, 7 Aug 2017 16:38:35 -0400 Message-Id: <1502138329-123460-2-git-send-email-pasha.tatashin@oracle.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1502138329-123460-1-git-send-email-pasha.tatashin@oracle.com> References: <1502138329-123460-1-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-20170807_134010_060133_403110A9 X-CRM114-Status: UNSURE ( 9.27 ) 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)); } /*