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Commit fa69b598 authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Linus Torvalds
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mm/kasan: add support for memory hotplug 

KASAN doesn't happen work with memory hotplug because hotplugged memory
doesn't have any shadow memory.  So any access to hotplugged memory
would cause a crash on shadow check.

Use memory hotplug notifier to allocate and map shadow memory when the
hotplugged memory is going online and free shadow after the memory
offlined.

Link: http://lkml.kernel.org/r/20170601162338.23540-4-aryabinin@virtuozzo.com


Signed-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3f9ec80f

mm/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -161,7 +161,6 @@ config MEMORY_HOTPLUG 
	bool "Allow for memory hot-add"

	depends on SPARSEMEM || X86_64_ACPI_NUMA

	depends on ARCH_ENABLE_MEMORY_HOTPLUG

	depends on COMPILE_TEST || !KASAN



config MEMORY_HOTPLUG_SPARSE

	def_bool y

mm/kasan/kasan.c

+35 −5
Original line number Diff line number Diff line
@@ -737,17 +737,47 @@ void __asan_unpoison_stack_memory(const void *addr, size_t size) 
EXPORT_SYMBOL(__asan_unpoison_stack_memory);



#ifdef CONFIG_MEMORY_HOTPLUG

static int kasan_mem_notifier(struct notifier_block *nb,

static int __meminit kasan_mem_notifier(struct notifier_block *nb,

			unsigned long action, void *data)

{

	return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;

	struct memory_notify *mem_data = data;

	unsigned long nr_shadow_pages, start_kaddr, shadow_start;

	unsigned long shadow_end, shadow_size;



	nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;

	start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);

	shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);

	shadow_size = nr_shadow_pages << PAGE_SHIFT;

	shadow_end = shadow_start + shadow_size;



	if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||

		WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))

		return NOTIFY_BAD;



	switch (action) {

	case MEM_GOING_ONLINE: {

		void *ret;



		ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,

					shadow_end, GFP_KERNEL,

					PAGE_KERNEL, VM_NO_GUARD,

					pfn_to_nid(mem_data->start_pfn),

					__builtin_return_address(0));

		if (!ret)

			return NOTIFY_BAD;



		kmemleak_ignore(ret);

		return NOTIFY_OK;

	}

	case MEM_OFFLINE:

		vfree((void *)shadow_start);

	}



	return NOTIFY_OK;

}



static int __init kasan_memhotplug_init(void)

{

	pr_info("WARNING: KASAN doesn't support memory hot-add\n");

	pr_info("Memory hot-add will be disabled\n");



	hotplug_memory_notifier(kasan_mem_notifier, 0);



	return 0;