+ mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange.patch added to mm-new branch

+ mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm: cma: set early_pfn and bitmap as a union in cma_memrange
has been added to the -mm mm-new branch.  Its filename is
     mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
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------------------------------------------------------
From: Zhongkun He <hezhongkun.hzk@bytedance.com>
Subject: mm: cma: set early_pfn and bitmap as a union in cma_memrange
Date: Fri, 9 May 2025 16:35:28 +0800

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>
---

 mm/cma.c |   11 ++++++-----
 mm/cma.h |    6 ++++--
 2 files changed, 10 insertions(+), 7 deletions(-)

--- a/mm/cma.c~mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange
+++ a/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(str
 
 	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));
 		}
 	}
--- a/mm/cma.h~mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange
+++ a/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
_

Patches currently in -mm which might be from hezhongkun.hzk@bytedance.com are

mm-add-swappiness=max-arg-to-memoryreclaim-for-only-anon-reclaim.patch
mm-vmscan-add-more-comments-about-cache_trim_mode.patch
mm-add-max-swappiness-arg-to-lru_gen-for-anonymous-memory-only.patch
mm-add-max-swappiness-arg-to-lru_gen-for-anonymous-memory-only-update.patch
mm-using-swappiness_anon_only-in-mglru.patch
mm-cma-set-early_pfn-and-bitmap-as-a-union-in-cma_memrange.patch