[PATCH v1 2/4] memblock: update initialization of reserved pages

Mike Rapoport
2021-04-20T09:14:32Z

From: Mike Rapoport <rppt@linux.ibm.com>

The struct pages representing a reserved memory region are initialized
using reserve_bootmem_range() function. This function is called for each
reserved region just before the memory is freed from memblock to the buddy
page allocator.

The struct pages for MEMBLOCK_NOMAP regions are kept with the default
values set by the memory map initialization which makes it necessary to
have a special treatment for such pages in pfn_valid() and
pfn_valid_within().

Split out initialization of the reserved pages to a function with a
meaningful name and treat the MEMBLOCK_NOMAP regions the same way as the
reserved regions and mark struct pages for the NOMAP regions as
PageReserved.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
include/linux/memblock.h | 4 +++-
mm/memblock.c | 28 ++++++++++++++++++++++++++--
2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 5984fff3f175..634c1a578db8 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -30,7 +30,9 @@ extern unsigned long long max_possible_pfn;
* @MEMBLOCK_NONE: no special request
* @MEMBLOCK_HOTPLUG: hotpluggable region
* @MEMBLOCK_MIRROR: mirrored region
- * @MEMBLOCK_NOMAP: don't add to kernel direct mapping
+ * @MEMBLOCK_NOMAP: don't add to kernel direct mapping and treat as
+ * reserved in the memory map; refer to memblock_mark_nomap() description
+ * for futher details
*/
enum memblock_flags {
MEMBLOCK_NONE = 0x0, /* No special request */
diff --git a/mm/memblock.c b/mm/memblock.c
index afaefa8fc6ab..3abf2c3fea7f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -906,6 +906,11 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
* @base: the base phys addr of the region
* @size: the size of the region
*
+ * The memory regions marked with %MEMBLOCK_NOMAP will not be added to the
+ * direct mapping of the physical memory. These regions will still be
+ * covered by the memory map. The struct page representing NOMAP memory
+ * frames in the memory map will be PageReserved()
+ *
* Return: 0 on success, -errno on failure.
*/
int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
@@ -2002,6 +2007,26 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
return end_pfn - start_pfn;
}

+static void __init memmap_init_reserved_pages(void)
+{
+ struct memblock_region *region;
+ phys_addr_t start, end;
+ u64 i;
+
+ /* initialize struct pages for the reserved regions */
+ for_each_reserved_mem_range(i, &start, &end)
+ reserve_bootmem_region(start, end);
+
+ /* and also treat struct pages for the NOMAP regions as PageReserved */
+ for_each_mem_region(region) {
+ if (memblock_is_nomap(region)) {
+ start = region->base;
+ end = start + region->size;
+ reserve_bootmem_region(start, end);
+ }
+ }
+}
+
static unsigned long __init free_low_memory_core_early(void)
{
unsigned long count = 0;
@@ -2010,8 +2035,7 @@ static unsigned long __init free_low_memory_core_early(void)

memblock_clear_hotplug(0, -1);

- for_each_reserved_mem_range(i, &start, &end)
- reserve_bootmem_region(start, end);
+ memmap_init_reserved_pages();

/*
* We need to use NUMA_NO_NODE instead of NODE_DATA(0)->node_id
--
2.28.0