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.
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
mm/Kconfig | 1 -
mm/kasan/kasan.c | 40 +++++++++++++++++++++++++++++++++++-----
2 files changed, 35 insertions(+), 6 deletions(-)
diff --git a/mm/Kconfig b/mm/Kconfig
index f1fbde17d45d..c8df94059974 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -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
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index e6fe07a98677..ca11bc4ce205 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -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;
--
2.13.0
--
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