memory hotplug: fix a bug on /dev/mem for 64-bit kernels (ea085417) · Commits · 戴 / test

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 <shaohui.zheng@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Li Haicheng <haicheng.li@intel.com> Reviewed-by:

Wu Fengguang <fengguang.wu@intel.com> Reviewed-by:

KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/init_64.c

+19 −0

Original line number	Diff line number	Diff line
		@@ -49,6 +49,7 @@
		#include <asm/numa.h>
		#include <asm/cacheflush.h>
		#include <asm/init.h>
		#include <linux/bootmem.h>

		static unsigned long dma_reserve __initdata;

		@@ -615,6 +616,21 @@ void __init paging_init(void)
		* Memory hotplug specific functions
		*/
		#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);

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