[PATCH v4 18/19] mm/hugetlb: Remove unused bootmem cma field

[Muchun Song <songmuchun@bytedance.com>]

struct huge_bootmem_page no longer needs to keep the CMA pointer. The
bootmem path only needs to remember whether a huge page came from CMA,
which is already encoded in the flags field.

Set HUGE_BOOTMEM_CMA when the page is allocated, drop the unused cma
field together with the redundant assignments, and simplify the early
CMA bootmem allocation fallback path now that the cma pointer no longer
has to be stored in struct huge_bootmem_page.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>

---
v3->v4:
- Clarify in the changelog that the patch also refactors the early CMA
  bootmem allocation path (suggested by Mike Rapoport)
---
 mm/hugetlb.c     |  5 +----
 mm/hugetlb_cma.c | 29 +++++++++++------------------
 mm/internal.h    |  2 --
 3 files changed, 12 insertions(+), 24 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 47c3d6d11c58..fb7ad2a4a26b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3076,10 +3076,7 @@ static bool __init alloc_bootmem_huge_page(struct hstate *h, int nid)
 	 */
 	INIT_LIST_HEAD(&m->list);
 	m->hstate = h;
-	if (!hugetlb_early_cma(h)) {
-		m->cma = NULL;
-		m->flags = 0;
-	}
+	m->flags = hugetlb_early_cma(h) ? HUGE_BOOTMEM_CMA : 0;
 
 	/* CMA pages: zone-crossing is validated in hugetlb_cma_reserve(). */
 	if (!hugetlb_early_cma(h) &&
diff --git a/mm/hugetlb_cma.c b/mm/hugetlb_cma.c
index e487d0ffffc0..4dfce68b354a 100644
--- a/mm/hugetlb_cma.c
+++ b/mm/hugetlb_cma.c
@@ -59,31 +59,24 @@ struct folio *hugetlb_cma_alloc_frozen_folio(int order, gfp_t gfp_mask,
 void * __init hugetlb_cma_alloc_bootmem(struct hstate *h, int nid, bool node_exact)
 {
 	struct cma *cma;
-	struct huge_bootmem_page *m;
+	void *m;
 	int node;
 
 	cma = hugetlb_cma[nid];
 	m = cma_reserve_early(cma, huge_page_size(h));
-	if (!m) {
-		if (node_exact)
-			return NULL;
+	if (m || node_exact)
+		return m;
 
-		for_each_node_mask(node, hugetlb_bootmem_nodes) {
-			cma = hugetlb_cma[node];
-			if (!cma || node == nid)
-				continue;
-			m = cma_reserve_early(cma, huge_page_size(h));
-			if (m)
-				break;
-		}
-	}
-
-	if (m) {
-		m->flags = HUGE_BOOTMEM_CMA;
-		m->cma = cma;
+	for_each_node_mask(node, hugetlb_bootmem_nodes) {
+		cma = hugetlb_cma[node];
+		if (!cma || node == nid)
+			continue;
+		m = cma_reserve_early(cma, huge_page_size(h));
+		if (m)
+			return m;
 	}
 
-	return m;
+	return NULL;
 }
 
 static int __init cmdline_parse_hugetlb_cma(char *p)
diff --git a/mm/internal.h b/mm/internal.h
index 3401759924d9..39c9564fba0e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -24,13 +24,11 @@
 
 struct folio_batch;
 struct hstate;
-struct cma;
 
 struct huge_bootmem_page {
 	struct list_head list;
 	struct hstate *hstate;
 	unsigned long flags;
-	struct cma *cma;
 };
 
 /*
-- 
2.54.0