From patchwork Thu Feb 4 07:01:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 12066413 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=-11.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 37389C433E6 for ; Thu, 4 Feb 2021 07:01:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A8FF064E35 for ; Thu, 4 Feb 2021 07:01:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8FF064E35 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1D75C6B0005; Thu, 4 Feb 2021 02:01:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1869C6B006C; Thu, 4 Feb 2021 02:01:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 09DA16B006E; Thu, 4 Feb 2021 02:01:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0100.hostedemail.com [216.40.44.100]) by kanga.kvack.org (Postfix) with ESMTP id E52886B0005 for ; Thu, 4 Feb 2021 02:01:10 -0500 (EST) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id CBE56180AD81F for ; Thu, 4 Feb 2021 07:01:09 +0000 (UTC) X-FDA: 77779688658.12.spoon10_550b2d3275da Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin12.hostedemail.com (Postfix) with ESMTP id B0F4018004A03 for ; Thu, 4 Feb 2021 07:01:09 +0000 (UTC) X-HE-Tag: spoon10_550b2d3275da X-Filterd-Recvd-Size: 5509 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Thu, 4 Feb 2021 07:01:08 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EAFED11FB; Wed, 3 Feb 2021 23:01:07 -0800 (PST) Received: from p8cg001049571a15.arm.com (unknown [10.163.94.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 472063F694; Wed, 3 Feb 2021 23:01:04 -0800 (PST) From: Anshuman Khandual To: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, akpm@linux-foundation.org Cc: Anshuman Khandual , Will Deacon , Robin Murphy , Marek Szyprowski , Christoph Hellwig , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [RFC 0/3] mm/page_alloc: Fix pageblock_order with HUGETLB_PAGE_SIZE_VARIABLE Date: Thu, 4 Feb 2021 12:31:21 +0530 Message-Id: <1612422084-30429-1-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 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: The following warning gets triggered while trying to boot a 64K page size without THP config kernel on arm64 platform. WARNING: CPU: 5 PID: 124 at mm/vmstat.c:1080 __fragmentation_index+0xa4/0xc0 Modules linked in: CPU: 5 PID: 124 Comm: kswapd0 Not tainted 5.11.0-rc6-00004-ga0ea7d62002 #159 Hardware name: linux,dummy-virt (DT) [ 8.810673] pstate: 20400005 (nzCv daif +PAN -UAO -TCO BTYPE=--) [ 8.811732] pc : __fragmentation_index+0xa4/0xc0 [ 8.812555] lr : fragmentation_index+0xf8/0x138 [ 8.813360] sp : ffff0000864079b0 [ 8.813958] x29: ffff0000864079b0 x28: 0000000000000372 [ 8.814901] x27: 0000000000007682 x26: ffff8000135b3948 [ 8.815847] x25: 1fffe00010c80f48 x24: 0000000000000000 [ 8.816805] x23: 0000000000000000 x22: 000000000000000d [ 8.817764] x21: 0000000000000030 x20: ffff0005ffcb4d58 [ 8.818712] x19: 000000000000000b x18: 0000000000000000 [ 8.819656] x17: 0000000000000000 x16: 0000000000000000 [ 8.820613] x15: 0000000000000000 x14: ffff8000114c6258 [ 8.821560] x13: ffff6000bff969ba x12: 1fffe000bff969b9 [ 8.822514] x11: 1fffe000bff969b9 x10: ffff6000bff969b9 [ 8.823461] x9 : dfff800000000000 x8 : ffff0005ffcb4dcf [ 8.824415] x7 : 0000000000000001 x6 : 0000000041b58ab3 [ 8.825359] x5 : ffff600010c80f48 x4 : dfff800000000000 [ 8.826313] x3 : ffff8000102be670 x2 : 0000000000000007 [ 8.827259] x1 : ffff000086407a60 x0 : 000000000000000d [ 8.828218] Call trace: [ 8.828667] __fragmentation_index+0xa4/0xc0 [ 8.829436] fragmentation_index+0xf8/0x138 [ 8.830194] compaction_suitable+0x98/0xb8 [ 8.830934] wakeup_kcompactd+0xdc/0x128 [ 8.831640] balance_pgdat+0x71c/0x7a0 [ 8.832327] kswapd+0x31c/0x520 [ 8.832902] kthread+0x224/0x230 [ 8.833491] ret_from_fork+0x10/0x30 [ 8.834150] ---[ end trace 472836f79c15516b ]--- This warning comes from __fragmentation_index() when the requested order is greater than MAX_ORDER. static int __fragmentation_index(unsigned int order, struct contig_page_info *info) { unsigned long requested = 1UL << order; if (WARN_ON_ONCE(order >= MAX_ORDER)) <===== Triggered here return 0; Digging it further reveals that pageblock_order has been assigned a value which is greater than MAX_ORDER failing the above check. But why this happened ? Because HUGETLB_PAGE_ORDER for the given config on arm64 is greater than MAX_ORDER. The solution involves enabling HUGETLB_PAGE_SIZE_VARIABLE which would make pageblock_order a variable instead of constant HUGETLB_PAGE_ORDER. But that change alone also did not really work as pageblock_order still got assigned as HUGETLB_PAGE_ORDER in set_pageblock_order(). HUGETLB_PAGE_ORDER needs to be less than MAX_ORDER for its appropriateness as pageblock_order otherwise just fallback to MAX_ORDER - 1 as before. While here it also fixes a build problem via type casting MAX_ORDER in rmem_cma_setup(). This series applies in v5.11-rc6 and has been slightly tested on arm64. But looking for some early feedbacks particularly with respect to concerns in subscribing HUGETLB_PAGE_SIZE_VARIABLE on a platform where the hugetlb page size is config dependent but not really a runtime variable. Even though it appears that HUGETLB_PAGE_SIZE_VARIABLE is used only while computing the pageblock_order, could there be other implications ? Cc: Catalin Marinas Cc: Will Deacon Cc: Robin Murphy Cc: Marek Szyprowski Cc: Christoph Hellwig Cc: Andrew Morton Cc: linux-arm-kernel@lists.infradead.org Cc: iommu@lists.linux-foundation.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Anshuman Khandual (3): mm/page_alloc: Fix pageblock_order when HUGETLB_PAGE_ORDER >= MAX_ORDER arm64/hugetlb: Enable HUGETLB_PAGE_SIZE_VARIABLE dma-contiguous: Type cast MAX_ORDER as unsigned int arch/arm64/Kconfig | 4 ++++ kernel/dma/contiguous.c | 2 +- mm/page_alloc.c | 2 +- 3 files changed, 6 insertions(+), 2 deletions(-)