From patchwork Fri Feb 24 19:33:58 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nishanth Aravamudan X-Patchwork-Id: 142963 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from ozlabs.org (localhost [IPv6:::1]) by ozlabs.org (Postfix) with ESMTP id 059D0B6FE7 for ; Sat, 25 Feb 2012 06:35:26 +1100 (EST) Received: from e39.co.us.ibm.com (e39.co.us.ibm.com [32.97.110.160]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e39.co.us.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 4C6E2B6EEA for ; Sat, 25 Feb 2012 06:34:11 +1100 (EST) Received: from /spool/local by e39.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 24 Feb 2012 12:34:06 -0700 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id 38CBDC9004D for ; Fri, 24 Feb 2012 14:34:05 -0500 (EST) Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q1OJY4Or188494 for ; Fri, 24 Feb 2012 14:34:04 -0500 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q1OJY1eU017076 for ; Fri, 24 Feb 2012 12:34:02 -0700 Received: from arkanoid.localdomain (dyn9050020227.mts.ibm.com [9.50.20.227] (may be forged)) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q1OJY1Gb016854; Fri, 24 Feb 2012 12:34:01 -0700 Received: by arkanoid.localdomain (Postfix, from userid 1000) id 5C2AEF2A10; Fri, 24 Feb 2012 11:33:58 -0800 (PST) From: Nishanth Aravamudan To: Andrew Morton Subject: [PATCH] sparsemem/bootmem: catch greater than section size allocations Date: Fri, 24 Feb 2012 11:33:58 -0800 Message-Id: <1330112038-18951-1-git-send-email-nacc@us.ibm.com> X-Mailer: git-send-email 1.7.5.4 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12022419-4242-0000-0000-000000DDDF22 Cc: Anton Blanchard , Dave Hansen , linux-mm@kvack.org, Paul Mackerras , Robert Jennings , linuxppc-dev@lists.ozlabs.org X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org While testing AMS (Active Memory Sharing) / CMO (Cooperative Memory Overcommit) on powerpc, we tripped the following: kernel BUG at mm/bootmem.c:483! cpu 0x0: Vector: 700 (Program Check) at [c000000000c03940] pc: c000000000a62bd8: .alloc_bootmem_core+0x90/0x39c lr: c000000000a64bcc: .sparse_early_usemaps_alloc_node+0x84/0x29c sp: c000000000c03bc0 msr: 8000000000021032 current = 0xc000000000b0cce0 paca = 0xc000000001d80000 pid = 0, comm = swapper kernel BUG at mm/bootmem.c:483! enter ? for help [c000000000c03c80] c000000000a64bcc .sparse_early_usemaps_alloc_node+0x84/0x29c [c000000000c03d50] c000000000a64f10 .sparse_init+0x12c/0x28c [c000000000c03e20] c000000000a474f4 .setup_arch+0x20c/0x294 [c000000000c03ee0] c000000000a4079c .start_kernel+0xb4/0x460 [c000000000c03f90] c000000000009670 .start_here_common+0x1c/0x2c This is BUG_ON(limit && goal + size > limit); and after some debugging, it seems that goal = 0x7ffff000000 limit = 0x80000000000 and sparse_early_usemaps_alloc_node -> sparse_early_usemaps_alloc_pgdat_section -> alloc_bootmem_section calls return alloc_bootmem_section(usemap_size() * count, section_nr); This is on a system with 8TB available via the AMS pool, and as a quirk of AMS in firmware, all of that memory shows up in node 0. So, we end up with an allocation that will fail the goal/limit constraints. In theory, we could "fall-back" to alloc_bootmem_node() in sparse_early_usemaps_alloc_node(), but since we actually have HOTREMOVE defined, we'll BUG_ON() instead. A simple solution appears to be to disable the limit check if the size of the allocation in alloc_bootmem_secition exceeds the section size. Signed-off-by: Nishanth Aravamudan Cc: Dave Hansen Cc: Anton Blanchard Cc: Paul Mackerras Cc: Ben Herrenschmidt Cc: Robert Jennings Cc: linux-mm@kvack.org Cc: linuxppc-dev@lists.ozlabs.org --- include/linux/mmzone.h | 2 ++ mm/bootmem.c | 5 ++++- 2 files changed, 6 insertions(+), 1 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 650ba2f..4176834 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -967,6 +967,8 @@ static inline unsigned long early_pfn_to_nid(unsigned long pfn) * PA_SECTION_SHIFT physical address to/from section number * PFN_SECTION_SHIFT pfn to/from section number */ +#define BYTES_PER_SECTION (1UL << SECTION_SIZE_BITS) + #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) #define PA_SECTION_SHIFT (SECTION_SIZE_BITS) diff --git a/mm/bootmem.c b/mm/bootmem.c index 668e94d..5cbbc76 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -770,7 +770,10 @@ void * __init alloc_bootmem_section(unsigned long size, pfn = section_nr_to_pfn(section_nr); goal = pfn << PAGE_SHIFT; - limit = section_nr_to_pfn(section_nr + 1) << PAGE_SHIFT; + if (size > BYTES_PER_SECTION) + limit = 0; + else + limit = section_nr_to_pfn(section_nr + 1) << PAGE_SHIFT; bdata = &bootmem_node_data[early_pfn_to_nid(pfn)]; return alloc_bootmem_core(bdata, size, SMP_CACHE_BYTES, goal, limit);