[PATCH] mm/page_alloc.c: Add unavailable ranges into memblock

[Baoquan He]

These unavailable ranges shares the same section with the usable range
in boot memory, e.g the firmware reserved ranges, and holes.

Previously, they are added into node 0, zone 0 in function
init_unavailable_range(), and marked as Reserved. Later, in function
memmap_init(), they will be added to appropriate node and zone, where
they are covered.

However, after the patchset ("mm: rework free_area_init*() funcitons")
is applied, we change to iterate over memblock regions. These unavailable
ranges are skipped, and the node and zone adjustment won't be done any
more as the old code did. This cause a crash in compaction which is triggered
by VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn)).

So let's add these unavailable ranges into memblock and reserve them
in init_unavailable_range() instead. With this change, they will be added
into appropriate node and zone in memmap_init(), and initialized in
reserve_bootmem_region() just like any other memblock reserved regions.

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
 mm/page_alloc.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 603187800628..3973b5fdfe3f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6925,7 +6925,7 @@ static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn)
 static void __init init_unavailable_mem(void)
 {
 	phys_addr_t start, end;
-	u64 i, pgcnt;
+	u64 i, pgcnt, size;
 	phys_addr_t next = 0;
 
 	/*
@@ -6934,9 +6934,11 @@ static void __init init_unavailable_mem(void)
 	pgcnt = 0;
 	for_each_mem_range(i, &memblock.memory, NULL,
 			NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL) {
-		if (next < start)
-			pgcnt += init_unavailable_range(PFN_DOWN(next),
-							PFN_UP(start));
+		if (next < start) {
+			size = PFN_UP(start) - PFN_DOWN(next);
+			memblock_add(PFN_DOWN(next), size);
+			memblock_reserve(PFN_DOWN(next), size);
+		}
 		next = end;
 	}
 
@@ -6947,8 +6949,11 @@ static void __init init_unavailable_mem(void)
 	 * considered initialized. Make sure that memmap has a well defined
 	 * state.
 	 */
-	pgcnt += init_unavailable_range(PFN_DOWN(next),
-					round_up(max_pfn, PAGES_PER_SECTION));
+	size = round_up(max_pfn, PAGES_PER_SECTION) - PFN_DOWN(next);
+	if (size) {
+		memblock_add(PFN_DOWN(next), size);
+		memblock_reserve(PFN_DOWN(next), size);
+	}
 
 	/*
 	 * Struct pages that do not have backing memory. This could be because
-- 
2.17.2