From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f175.google.com (mail-ig0-f175.google.com [209.85.213.175]) by kanga.kvack.org (Postfix) with ESMTP id C598A6B0032 for ; Tue, 20 Jan 2015 20:38:05 -0500 (EST) Received: by mail-ig0-f175.google.com with SMTP id hn18so6505149igb.2 for ; Tue, 20 Jan 2015 17:38:05 -0800 (PST) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.11.231]) by mx.google.com with ESMTPS id h9si4895105icw.19.2015.01.20.17.38.04 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Jan 2015 17:38:04 -0800 (PST) From: Laura Abbott Subject: [PATCH] mm: Don't offset memmap for flatmem Date: Tue, 20 Jan 2015 17:37:53 -0800 Message-Id: <1421804273-29947-1-git-send-email-lauraa@codeaurora.org> In-reply-to: <54BE25EF.3060004@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Srinivas Kandagatla , linux-arm-kernel@lists.infradead.org, Russell King - ARM Linux , ssantosh@kernel.org, Andrew Morton , Vlastimil Babka Cc: Laura Abbott , Kevin Kilman , Stephen Boyd , Arnd Bergman , Kumar Gala , linux-mm@kvack.org Srinivas Kandagatla reported bad page messages when trying to remove the bottom 2MB on an ARM based IFC6410 board BUG: Bad page state in process swapper pfn:fffa8 page:ef7fb500 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x96640253(locked|error|dirty|active|arch_1|reclaim|mlocked) page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set bad because of flags: flags: 0x200041(locked|active|mlocked) Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 3.19.0-rc3-00007-g412f9ba-dirty #816 Hardware name: Qualcomm (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x20/0x24) [] (show_stack) from [] (dump_stack+0x80/0x9c) [] (dump_stack) from [] (bad_page+0xc8/0x128) [] (bad_page) from [] (free_pages_prepare+0x168/0x1e0) [] (free_pages_prepare) from [] (free_hot_cold_page+0x3c/0x174) [] (free_hot_cold_page) from [] (__free_pages+0x54/0x58) [] (__free_pages) from [] (free_highmem_page+0x38/0x88) [] (free_highmem_page) from [] (mem_init+0x240/0x430) [] (mem_init) from [] (start_kernel+0x1e4/0x3c8) [] (start_kernel) from [<80208074>] (0x80208074) Disabling lock debugging due to kernel taint Removing the lower 2MB made the start of the lowmem zone to no longer be page block aligned. IFC6410 uses CONFIG_FLATMEM where alloc_node_mem_map allocates memory for the mem_map. alloc_node_mem_map will offset for unaligned nodes with the assumption the pfn/page translation functions will account for the offset. The functions for CONFIG_FLATMEM do not offset however, resulting in overrunning the memmap array. Just use the allocated memmap without any offset when running with CONFIG_FLATMEM to avoid the overrun. Signed-off-by: Laura Abbott Reported-by: Srinivas Kandagatla --- Srinivas, can you test this version of the patch? --- mm/page_alloc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 7633c50..33cef00 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5014,6 +5014,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) if (!pgdat->node_mem_map) { unsigned long size, start, end; struct page *map; + unsigned long offset = 0; /* * The zone's endpoints aren't required to be MAX_ORDER @@ -5021,6 +5022,8 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) * for the buddy allocator to function correctly. */ start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1); + if (!IS_ENABLED(CONFIG_FLATMEM)) + offset = pgdat->node_start_pfn - start; end = pgdat_end_pfn(pgdat); end = ALIGN(end, MAX_ORDER_NR_PAGES); size = (end - start) * sizeof(struct page); @@ -5028,7 +5031,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) if (!map) map = memblock_virt_alloc_node_nopanic(size, pgdat->node_id); - pgdat->node_mem_map = map + (pgdat->node_start_pfn - start); + pgdat->node_mem_map = map + offset; } #ifndef CONFIG_NEED_MULTIPLE_NODES /* -- Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org