[RFC PATCH 1/2] memblock: factor out the KHO bootmem check from memblock_alloc_hugetlb()

["Jose A. Perez de Azpillaga" <azpijr@gmail.com>]

reserve_mem regions are preserved with KHO too, and need the same search
that keeps HugeTLB pages out of KHO bootmem. Move it into a helper.

No functional change intended.

Signed-off-by: Jose A. Perez de Azpillaga <azpijr@gmail.com>
---
 mm/memblock.c | 70 ++++++++++++++++++++++++++-------------------------
 1 file changed, 36 insertions(+), 34 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index a450092a80fb..f43659688681 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1744,6 +1744,31 @@ void * __init memblock_alloc_try_nid_raw(
 	return memblock_alloc_internal(size, align, min_addr, max_addr, nid);
 }
 
+/*
+ * Memory that can be preserved with KHO can't be in KHO bootmem, since the
+ * next kernel boots out of it. Bootmem areas are normally not very large, so
+ * this shouldn't take too many retries.
+ */
+static phys_addr_t __init memblock_find_outside_kho_bootmem(phys_addr_t size,
+					phys_addr_t align, int nid,
+					enum memblock_flags flags)
+{
+	phys_addr_t addr, start = 0, end = MEMBLOCK_ALLOC_ACCESSIBLE;
+
+	while ((addr = memblock_find_in_range_node(size, align, start, end,
+						   nid, flags))) {
+		if (!kho_bootmem_overlap(addr, size))
+			break;
+
+		if (memblock_bottom_up())
+			start = addr + size;
+		else
+			end = addr;
+	}
+
+	return addr;
+}
+
 /**
  * memblock_alloc_hugetlb - allocate boot memory for HugeTLB pages
  * @size:      size of the memory to be allocated in bytes
@@ -1761,52 +1786,29 @@ void * __init memblock_alloc_try_nid_raw(
 void * __init memblock_alloc_hugetlb(phys_addr_t size, int nid, bool exact_nid)
 {
 	enum memblock_flags flags = choose_memblock_flags();
-	phys_addr_t addr, start = 0, end = MEMBLOCK_ALLOC_ACCESSIBLE;
+	phys_addr_t addr;
 
 	memblock_dbg("%s: %llu bytes, nid=%d, exact_nid=%d %pS\n", __func__,
 		     (u64)size, nid, exact_nid, (void *)_RET_IP_);
 
 	/* Don't waste mirrored memory on HugeTLB pages. */
 	flags &= ~MEMBLOCK_MIRROR;
-retry:
-	/* HugeTLB pages are always aligned by their size. */
-	addr = memblock_find_in_range_node(size, size, start, end, nid, flags);
-	if (addr)
-		goto found;
+
+	/*
+	 * HugeTLB pages are always aligned by their size, and can be preserved
+	 * with KHO.
+	 */
+	addr = memblock_find_outside_kho_bootmem(size, size, nid, flags);
 
 	/* Try all nodes if allowed. */
-	if (numa_valid_node(nid) && !exact_nid) {
+	if (!addr && numa_valid_node(nid) && !exact_nid) {
 		nid = NUMA_NO_NODE;
-		/*
-		 * If a previous candidate overlapped with KHO bootmem, it would
-		 * update start or end. Now that the search is opening to all
-		 * nodes, reset them.
-		 */
-		start = 0;
-		end = MEMBLOCK_ALLOC_ACCESSIBLE;
-
-		goto retry;
+		addr = memblock_find_outside_kho_bootmem(size, size, nid, flags);
 	}
 
 	/* Found nothing... :-( */
-	return NULL;
-
-found:
-	/*
-	 * HugeTLB pages can be preserved with KHO and no preserved memory can
-	 * be in bootmem. So retry if found address overlaps with bootmem.
-	 *
-	 * Bootmem areas are normally not very large, so this shouldn't take too
-	 * many retries.
-	 */
-	if (kho_bootmem_overlap(addr, size)) {
-		if (memblock_bottom_up())
-			start = addr + size;
-		else
-			end = addr;
-
-		goto retry;
-	}
+	if (!addr)
+		return NULL;
 
 	if (__memblock_reserve(addr, size, nid, MEMBLOCK_RSRV_KERN | MEMBLOCK_RSRV_HUGETLB))
 		return NULL;
-- 
2.55.0