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 15632939f20a1e548910d2e626e97e6e8cdb8ee3..ec4b9a401b7d362b64edb36d71267d23bf7aefe7 100644 (file)
--- 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 41a3ab0ec3deb4dd9fdfb2aa4f52982e8b3a1f99..c70180c36559c295d837725e26596cf546cd8b7e 100644 (file)
--- 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