From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxx Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Mark Rutland <mark.rutland@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/Kconfig | 1 - mm/kasan/kasan.c | 40 +++++++++++++++++++++++++++++++++++----- 2 files changed, 35 insertions(+), 6 deletions(-) diff -puN mm/Kconfig~mm-kasan-add-support-for-memory-hotplug mm/Kconfig --- a/mm/Kconfig~mm-kasan-add-support-for-memory-hotplug +++ a/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 -puN mm/kasan/kasan.c~mm-kasan-add-support-for-memory-hotplug mm/kasan/kasan.c --- a/mm/kasan/kasan.c~mm-kasan-add-support-for-memory-hotplug +++ a/mm/kasan/kasan.c @@ -737,17 +737,47 @@ void __asan_unpoison_stack_memory(const 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; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
