From ea0854170c95245a258b386c7a9314399c949fe0 Mon Sep 17 00:00:00 2001 From: Shaohui Zheng Date: Tue, 2 Feb 2010 13:44:16 -0800 Subject: [PATCH] memory hotplug: fix a bug on /dev/mem for 64-bit kernels Newly added memory can not be accessed via /dev/mem, because we do not update the variables high_memory, max_pfn and max_low_pfn. Add a function update_end_of_memory_vars() to update these variables for 64-bit kernels. [akpm@linux-foundation.org: simplify comment] Signed-off-by: Shaohui Zheng Cc: Andi Kleen Cc: Li Haicheng Reviewed-by: Wu Fengguang Reviewed-by: KAMEZAWA Hiroyuki Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/mm/init_64.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 5198b9b..69ddfbd 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -49,6 +49,7 @@ #include #include #include +#include static unsigned long dma_reserve __initdata; @@ -616,6 +617,21 @@ void __init paging_init(void) */ #ifdef CONFIG_MEMORY_HOTPLUG /* + * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need + * updating. + */ +static void update_end_of_memory_vars(u64 start, u64 size) +{ + unsigned long end_pfn = PFN_UP(start + size); + + if (end_pfn > max_pfn) { + max_pfn = end_pfn; + max_low_pfn = end_pfn; + high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1; + } +} + +/* * Memory is added always to NORMAL zone. This means you will never get * additional DMA/DMA32 memory. */ @@ -634,6 +650,9 @@ int arch_add_memory(int nid, u64 start, u64 size) ret = __add_pages(nid, zone, start_pfn, nr_pages); WARN_ON_ONCE(ret); + /* update max_pfn, max_low_pfn and high_memory */ + update_end_of_memory_vars(start, size); + return ret; } EXPORT_SYMBOL_GPL(arch_add_memory); -- 2.7.4