From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752562AbdHNOaQ (ORCPT ); Mon, 14 Aug 2017 10:30:16 -0400 Received: from mga04.intel.com ([192.55.52.120]:21226 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752483AbdHNOaN (ORCPT ); Mon, 14 Aug 2017 10:30:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,373,1498546800"; d="scan'208";a="1205501433" Date: Mon, 14 Aug 2017 17:29:08 +0300 From: "Kirill A. Shutemov" To: Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Cc: Andi Kleen , Dave Hansen , Andy Lutomirski , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv4 01/14] mm/sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME Message-ID: <20170814142907.kkch4ar5jdoeg2cd@black.fi.intel.com> References: <20170808125415.78842-1-kirill.shutemov@linux.intel.com> <20170808125415.78842-2-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170808125415.78842-2-kirill.shutemov@linux.intel.com> User-Agent: NeoMutt/20170714-126-deb55f (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 08, 2017 at 12:54:02PM +0000, Kirill A. Shutemov wrote: > Size of mem_section array depends on size of physical address space. > > In preparation for boot-time switching between paging modes on x86-64 > we need to make allocation of mem_section dynamic. > > The patch allocates the array on the first call to > sparse_memory_present_with_active_regions(). > > Signed-off-by: Kirill A. Shutemov Fixup for the patch: diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index c8eb668eab79..9799c2c58ce6 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1144,6 +1144,10 @@ extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]; static inline struct mem_section *__nr_to_section(unsigned long nr) { +#ifdef CONFIG_SPARSEMEM_EXTREME + if (!mem_section) + return NULL; +#endif if (!mem_section[SECTION_NR_TO_ROOT(nr)]) return NULL; return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK]; -- Kirill A. Shutemov