[PATCH v4 12/19] mm/hugetlb_cma: Validate hugetlb CMA range by zone at reserve time

[Muchun Song <songmuchun@bytedance.com>]

Hugetlb CMA allocation currently has to cope with CMA areas that span
multiple zones.

Validate the reserved CMA range up front in hugetlb_cma_reserve() so
later hugetlb CMA allocations can assume a zone-consistent area.

Also drop the pfn_valid() check from cma_validate_zones(). mem_section
is not fully initialized at this point, so the check can trigger false
warnings. Keep the sanity check in cma_activate_area() instead.

Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador (SUSE) <osalvador@suse.de>
---
 mm/cma.c         | 3 ++-
 mm/hugetlb_cma.c | 6 ++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index a13ce4999b39..31073738f2ac 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -126,7 +126,6 @@ bool cma_validate_zones(struct cma *cma)
 		 * to be in the same zone. Simplify by forcing the entire
 		 * CMA resv range to be in the same zone.
 		 */
-		WARN_ON_ONCE(!pfn_valid(base_pfn));
 		if (pfn_range_intersects_zones(cma->nid, base_pfn, cmr->count)) {
 			set_bit(CMA_ZONES_INVALID, &cma->flags);
 			return false;
@@ -165,6 +164,8 @@ static void __init cma_activate_area(struct cma *cma)
 			bitmap_set(cmr->bitmap, 0, bitmap_count);
 		}
 
+		WARN_ON_ONCE(!pfn_valid(cmr->base_pfn));
+
 		for (pfn = early_pfn[r]; pfn < cmr->base_pfn + cmr->count;
 		     pfn += pageblock_nr_pages)
 			init_cma_reserved_pageblock(pfn_to_page(pfn));
diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c
index 39344d6c78d8..ce999391cc14 100644
--- a/mm/hugetlb_cma.c
+++ b/mm/hugetlb_cma.c
@@ -231,9 +231,11 @@ void __init hugetlb_cma_reserve(void)
 		res = cma_declare_contiguous_multi(size, gigantic_page_size,
 					HUGETLB_PAGE_ORDER, name,
 					&hugetlb_cma[nid], nid);
-		if (res) {
-			pr_warn("hugetlb_cma: reservation failed: err %d, node %d",
+		if (res || !cma_validate_zones(hugetlb_cma[nid])) {
+			pr_warn("hugetlb_cma: %s: err %d, node %d\n",
+				res ? "reservation failed" : "reserved area spans zones",
 				res, nid);
+			hugetlb_cma[nid] = NULL;
 			continue;
 		}
 
-- 
2.54.0