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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 B621AC2BA19 for ; Thu, 9 Apr 2020 21:58:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8C6F92072F for ; Thu, 9 Apr 2020 21:58:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CPX2S6Eq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726814AbgDIV6J (ORCPT ); Thu, 9 Apr 2020 17:58:09 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:54392 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726638AbgDIV6J (ORCPT ); Thu, 9 Apr 2020 17:58:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586469488; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=9YlJfp8gcnULlH0Iw/uIfxlGLQ2jILFfQLjgtpxox2c=; b=CPX2S6EqgkVyDWNZ3jyqJ7RQZsj2iauzpmEzVv6UiGzcZOVKL46ok2zVvx6NNGeVxs3ii+ cZOIF690nZaz0qPnNVIzWm8FwIBWZwnj+m45OSXUvZ6+4yqfAz6AXm2EG+NcBuhx9mSOVk U0Ls71+H+We7ripdttU8XPwzHYj0TS4= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-197-5Zx9rBwVPSm3qVpSfrjlqg-1; Thu, 09 Apr 2020 17:58:04 -0400 X-MC-Unique: 5Zx9rBwVPSm3qVpSfrjlqg-1 Received: by mail-qk1-f198.google.com with SMTP id a67so463685qke.0 for ; Thu, 09 Apr 2020 14:58:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9YlJfp8gcnULlH0Iw/uIfxlGLQ2jILFfQLjgtpxox2c=; b=suMcxAU5npu8ti2rTEOY2Wu6CyW2vwT1IKstyGtokZPst49p5X+fkxsNSGBz7SV7ad RgXAtIEdd14az0x3FGtV+cBve6IOPl/PcfKNQyp+FJk3rAkkivBdWPbHjGiQB0TJVsb/ V9QQa+Q8UXLtG1VChdjfFmaFRH9eTn4rYz7BXhFrsKrzfMalHPzqQr+2iPoDSGbA+jEj Q5lyxSgV13IQAkPayNON0kidD/lNkGU+g1yvo+S3LbUGI2KIN8N2cqUOalV9gxgZj+k1 0bjB9F6bk/8AdMtTR4kuBk5U4+wXFt5GLRoIikU75edwP+6LfEou+fu1Lu6q6Ptz08FK fWhQ== X-Gm-Message-State: AGi0PuZreYHmn7QXKGzF/rGkRNI4uNTDs4eATmlf1fux4KKIxx69rq1y n/BPaQZwrMzjuaKXrve6BLJggEhK0K07jM/l3WCnk7+yhwYZn1oSrVI2vMTQw7T6LsnUZxUvN1u UqA+xhv7OoCdW2OMLwhfoQ4/L X-Received: by 2002:ae9:e8c1:: with SMTP id a184mr988562qkg.242.1586469484034; Thu, 09 Apr 2020 14:58:04 -0700 (PDT) X-Google-Smtp-Source: APiQypKLmS8XXUNIiGvZvCrKQlsPyUcVaCnI5PoZiI1hPytd9AWi1VwgIeqBvXPZH/X8OoxSv8t7aw== X-Received: by 2002:ae9:e8c1:: with SMTP id a184mr988543qkg.242.1586469483726; Thu, 09 Apr 2020 14:58:03 -0700 (PDT) Received: from xz-x1.hitronhub.home ([2607:9880:19c0:32::2]) by smtp.gmail.com with ESMTPSA id m11sm103828qkg.130.2020.04.09.14.58.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Apr 2020 14:58:03 -0700 (PDT) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Nitesh Narayan Lal , peterx@redhat.com, Andrew Morton , Mike Kravetz Subject: [PATCH] Documentation: hugetlb: Update hugetlb options Date: Thu, 9 Apr 2020 17:58:00 -0400 Message-Id: <20200409215800.8967-1-peterx@redhat.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The hugepage options are not documented clearly. Firstly, default_hugepagesz= should always be specified after the declaration of the same type of huge page using hugepagesz=. For example, if we boot a x86_64 system with kernel cmdline "default_hugepagesz=2M", we'll get a very funny error message: "HugeTLB: unsupported default_hugepagesz 2097152. Reverting to 2097152" It's understandable from code-wise because when hugetlb_init() we didn't have the 2M page hstate registered, so it's unsupported. However 2M is actually the default huge page size on x86_64, so we'll register it right after the error message. However it's very confusing if without these knowledges. Secondly, hugepages= option must be used _after_ another hugepagesz=. The word "interleave" is fine but it didn't declare the fact that each of the hugepages= option will be applied to the previous parsed hugepagesz= option. State all these clear. Signed-off-by: Peter Xu --- .../admin-guide/kernel-parameters.txt | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 86aae1fa099a..2a77b2b01e5e 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -839,7 +839,8 @@ the legacy /proc/ hugepages APIs, used for SHM, and default size when mounting hugetlbfs filesystems. Defaults to the default architecture's huge page size - if not specified. + if not specified. This option can only be used with a + pre-defined "hugepagesz=" of the same size. deferred_probe_timeout= [KNL] Debugging option to set a timeout in seconds for @@ -1475,13 +1476,17 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. + hugepagesz= [HW,IA-64,PPC,X86-64] Declare one type of HugeTLB pages + with the size specified. Valid pages sizes on x86-64 + are 2M (when the CPU supports "pse") and 1G (when the + CPU supports the "pdpe1gb" cpuinfo flag). + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. - hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. - On x86-64 and powerpc, this option can be specified - multiple times interleaved with hugepages= to reserve - huge pages of different sizes. Valid pages sizes on - x86-64 are 2M (when the CPU supports "pse") and 1G - (when the CPU supports the "pdpe1gb" cpuinfo flag). + On x86-64 and powerpc, this option must be used after + one hugepagesz= to allocate huge pages of that specific + size. This option can also be used multiple times + pairing with hugepagesz= to allocate huge pages for + different sizes. hung_task_panic= [KNL] Should the hung task detector generate panics. -- 2.24.1