From a1c34a3bf00af2cede839879502e12dc68491ad5 Mon Sep 17 00:00:00 2001 From: Laura Abbott Date: Thu, 5 Nov 2015 18:48:46 -0800 Subject: [PATCH] mm: Don't offset memmap for flatmem 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 show_stack dump_stack bad_page free_pages_prepare free_hot_cold_page __free_pages free_highmem_page mem_init start_kernel 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 Signed-off-by: Laura Abbott Reported-by: Srinivas Kandagatla Tested-by: Srinivas Kandagatla Acked-by: Vlastimil Babka Tested-by: Bjorn Andersson Cc: Santosh Shilimkar Cc: Russell King Cc: Kevin Hilman Cc: Arnd Bergman Cc: Stephen Boyd Cc: Andy Gross Cc: Mel Gorman Cc: Steven Rostedt Cc: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4aed338fc535..86f7d952e2cc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5421,6 +5421,8 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat) static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) { + unsigned long __maybe_unused offset = 0; + /* Skip empty nodes */ if (!pgdat->node_spanned_pages) return; @@ -5437,6 +5439,7 @@ 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); + offset = pgdat->node_start_pfn - start; end = pgdat_end_pfn(pgdat); end = ALIGN(end, MAX_ORDER_NR_PAGES); size = (end - start) * sizeof(struct page); @@ -5444,7 +5447,7 @@ 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 /* @@ -5452,9 +5455,9 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat) */ if (pgdat == NODE_DATA(0)) { mem_map = NODE_DATA(0)->node_mem_map; -#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP +#if defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP) || defined(CONFIG_FLATMEM) if (page_to_pfn(mem_map) != pgdat->node_start_pfn) - mem_map -= (pgdat->node_start_pfn - ARCH_PFN_OFFSET); + mem_map -= offset; #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */ } #endif