From: Zhongkun He <hezhongkun.hzk@bytedance.com>
Date: Fri, 9 May 2025 08:35:28 +0000 (+0800)
Subject: mm: cma: set early_pfn and bitmap as a union in cma_memrange
X-Git-Tag: v6.16-rc1~92^2~39
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=83b6d498d027002e79c2ce40b5729137500c3170;p=thirdparty%2Fkernel%2Flinux.git

mm: cma: set early_pfn and bitmap as a union in cma_memrange

Since early_pfn and bitmap are never used at the same time, they can be
defined as a union to reduce the size of the data structure.  This change
can save 8 * u64 entries per CMA.

Link: https://lkml.kernel.org/r/20250509083528.1360952-1-hezhongkun.hzk@bytedance.com
Signed-off-by: Zhongkun He <hezhongkun.hzk@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/cma.c b/mm/cma.c
index 15632939f20a1..ec4b9a401b7d3 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -143,13 +143,14 @@ bool cma_validate_zones(struct cma *cma)
 
 static void __init cma_activate_area(struct cma *cma)
 {
-	unsigned long pfn, end_pfn;
+	unsigned long pfn, end_pfn, early_pfn[CMA_MAX_RANGES];
 	int allocrange, r;
 	struct cma_memrange *cmr;
 	unsigned long bitmap_count, count;
 
 	for (allocrange = 0; allocrange < cma->nranges; allocrange++) {
 		cmr = &cma->ranges[allocrange];
+		early_pfn[allocrange] = cmr->early_pfn;
 		cmr->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma, cmr),
 					    GFP_KERNEL);
 		if (!cmr->bitmap)
@@ -161,13 +162,13 @@ static void __init cma_activate_area(struct cma *cma)
 
 	for (r = 0; r < cma->nranges; r++) {
 		cmr = &cma->ranges[r];
-		if (cmr->early_pfn != cmr->base_pfn) {
-			count = cmr->early_pfn - cmr->base_pfn;
+		if (early_pfn[r] != cmr->base_pfn) {
+			count = early_pfn[r] - cmr->base_pfn;
 			bitmap_count = cma_bitmap_pages_to_bits(cma, count);
 			bitmap_set(cmr->bitmap, 0, bitmap_count);
 		}
 
-		for (pfn = cmr->early_pfn; pfn < cmr->base_pfn + cmr->count;
+		for (pfn = early_pfn[r]; pfn < cmr->base_pfn + cmr->count;
 		     pfn += pageblock_nr_pages)
 			init_cma_reserved_pageblock(pfn_to_page(pfn));
 	}
@@ -193,7 +194,7 @@ cleanup:
 		for (r = 0; r < allocrange; r++) {
 			cmr = &cma->ranges[r];
 			end_pfn = cmr->base_pfn + cmr->count;
-			for (pfn = cmr->early_pfn; pfn < end_pfn; pfn++)
+			for (pfn = early_pfn[r]; pfn < end_pfn; pfn++)
 				free_reserved_page(pfn_to_page(pfn));
 		}
 	}
diff --git a/mm/cma.h b/mm/cma.h
index 41a3ab0ec3deb..c70180c36559c 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -25,9 +25,11 @@ struct cma_kobject {
  */
 struct cma_memrange {
 	unsigned long base_pfn;
-	unsigned long early_pfn;
 	unsigned long count;
-	unsigned long *bitmap;
+	union {
+		unsigned long early_pfn;
+		unsigned long *bitmap;
+	};
 #ifdef CONFIG_CMA_DEBUGFS
 	struct debugfs_u32_array dfs_bitmap;
 #endif