On Mon, Jun 08, 2020 at 03:54:23PM +0300, Kirill A. Shutemov wrote:
A 5-level paging capable machine can have memory above 46-bit in the physical address space. This memory is only addressable in the 5-level paging mode: we don't have enough virtual address space to create direct mapping for such memory in the 4-level paging mode.
Currently, we fail boot completely: NULL pointer dereference in subsection_map_init().
Skip creating a memblock for such memory instead and notify user that some memory is not addressable.
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reviewed-by: Dave Hansen dave.hansen@intel.com Cc: stable@vger.kernel.org # v4.14
Reviewed-by: Mike Rapoport rppt@linux.ibm.com
arch/x86/kernel/e820.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index c5399e80c59c..c10bab121916 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -16,6 +16,7 @@ #include <linux/firmware-map.h> #include <linux/sort.h> #include <linux/memory_hotplug.h> +#include <linux/string_helpers.h> #include <asm/e820/api.h> #include <asm/setup.h> @@ -1280,8 +1281,8 @@ void __init e820__memory_setup(void) void __init e820__memblock_setup(void) {
- u64 size, end, not_addressable = 0; int i;
- u64 end;
/* * The bootstrap memblock region count maximum is 128 entries @@ -1307,7 +1308,26 @@ void __init e820__memblock_setup(void) if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) continue;
memblock_add(entry->addr, entry->size);
if (entry->addr >= MAXMEM) {not_addressable += entry->size;continue;}end = min_t(u64, end, MAXMEM - 1);size = end - entry->addr;not_addressable += entry->size - size;memblock_add(entry->addr, size);- }
- if (not_addressable) {
char tmp[10];string_get_size(not_addressable, 1, STRING_UNITS_2, tmp, sizeof(tmp));pr_err("%s of physical memory is not addressable in the %s paging mode\n",tmp, pgtable_l5_enabled() ? "5-level" : "4-level");if (!pgtable_l5_enabled())pr_err("Consider enabling 5-level paging\n");/* Throw away partial pages: */ -- 2.26.2