linux-kernel - [PATCH 08/21] mm: rejig pageblock mask definitions

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Message-ID: <20250924-b4-asi-page-alloc-v1-8-2d861768041f@google.com>
Date: Wed, 24 Sep 2025 14:59:43 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: jackmanb@...gle.com, Andy Lutomirski <luto@...nel.org>, 
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
	Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, 
	Johannes Weiner <hannes@...xchg.org>, Zi Yan <ziy@...dia.com>, 
	Axel Rasmussen <axelrasmussen@...gle.com>, Yuanchu Xie <yuanchu@...gle.com>, 
	Roman Gushchin <roman.gushchin@...ux.dev>
Cc: peterz@...radead.org, bp@...en8.de, dave.hansen@...ux.intel.com, 
	mingo@...hat.com, tglx@...utronix.de, akpm@...ux-foundation.org, 
	david@...hat.com, derkling@...gle.com, junaids@...gle.com, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, reijiw@...gle.com, 
	rientjes@...gle.com, rppt@...nel.org, vbabka@...e.cz, x86@...nel.org, 
	yosry.ahmed@...ux.dev
Subject: [PATCH 08/21] mm: rejig pageblock mask definitions

A later patch will complicate the definition of these masks, this is a
preparatory patch to make that patch easier to review.

- More masks will be needed, so add a PAGEBLOCK_ prefix to the names
  to avoid polluting the "global namespace" too much.

- Move the CONFIG_MEMORY_ISOLATION ifdeffery into a separate block, this
  allows the various conditionally-defined masks to be combined cleanly.

- This makes MIGRATETYPE_AND_ISO_MASK start to look pretty long. Well,
  that global mask only exists for quite a specific purpose so just drop
  it and take advantage of the newly-defined PAGEBLOCK_ISO_MASK.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 include/linux/pageblock-flags.h |  6 +++---
 mm/page_alloc.c                 | 18 +++++++++---------
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index e046278a01fa8c37d898df94114d088933b6747f..13457e920e892c1c5083e0dc63e2ecfbed88f60e 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -36,12 +36,12 @@ enum pageblock_bits {
 
 #define NR_PAGEBLOCK_BITS (roundup_pow_of_two(__NR_PAGEBLOCK_BITS))
 
-#define MIGRATETYPE_MASK (BIT(PB_migrate_0)|BIT(PB_migrate_1)|BIT(PB_migrate_2))
+#define PAGEBLOCK_MIGRATETYPE_MASK (BIT(PB_migrate_0)|BIT(PB_migrate_1)|BIT(PB_migrate_2))
 
 #ifdef CONFIG_MEMORY_ISOLATION
-#define MIGRATETYPE_AND_ISO_MASK (MIGRATETYPE_MASK | BIT(PB_migrate_isolate))
+#define PAGEBLOCK_ISO_MASK		BIT(PB_migrate_isolate)
 #else
-#define MIGRATETYPE_AND_ISO_MASK MIGRATETYPE_MASK
+#define PAGEBLOCK_ISO_MASK		0
 #endif
 
 #if defined(CONFIG_HUGETLB_PAGE)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0d1c28decd57b4a5e250acc0efc41669b7f67f5b..a1db87488296a6d2d91a1be8d4d202f1841c4dfd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -370,7 +370,7 @@ get_pfnblock_bitmap_bitidx(const struct page *page, unsigned long pfn,
 #else
 	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
 #endif
-	BUILD_BUG_ON(__MIGRATE_TYPE_END > MIGRATETYPE_MASK);
+	BUILD_BUG_ON(__MIGRATE_TYPE_END > PAGEBLOCK_MIGRATETYPE_MASK);
 	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
 
 	bitmap = get_pageblock_bitmap(page, pfn);
@@ -443,7 +443,7 @@ bool get_pfnblock_bit(const struct page *page, unsigned long pfn,
 __always_inline enum migratetype
 get_pfnblock_migratetype(const struct page *page, unsigned long pfn)
 {
-	unsigned long mask = MIGRATETYPE_AND_ISO_MASK;
+	unsigned long mask = PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK;
 	unsigned long flags;
 
 	flags = __get_pfnblock_flags_mask(page, pfn, mask);
@@ -452,7 +452,7 @@ get_pfnblock_migratetype(const struct page *page, unsigned long pfn)
 	if (flags & BIT(PB_migrate_isolate))
 		return MIGRATE_ISOLATE;
 #endif
-	return flags & MIGRATETYPE_MASK;
+	return flags & PAGEBLOCK_MIGRATETYPE_MASK;
 }
 
 /**
@@ -540,11 +540,11 @@ static void set_pageblock_migratetype(struct page *page,
 	}
 	VM_WARN_ONCE(get_pageblock_isolate(page),
 		     "Use clear_pageblock_isolate() to unisolate pageblock");
-	/* MIGRATETYPE_AND_ISO_MASK clears PB_migrate_isolate if it is set */
+	/* PAGEBLOCK_ISO_MASK clears PB_migrate_isolate if it is set */
 #endif
 	__set_pfnblock_flags_mask(page, page_to_pfn(page),
 				  (unsigned long)migratetype,
-				  MIGRATETYPE_AND_ISO_MASK);
+				  PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK);
 }
 
 void __meminit init_pageblock_migratetype(struct page *page,
@@ -570,7 +570,7 @@ void __meminit init_pageblock_migratetype(struct page *page,
 		flags |= BIT(PB_migrate_isolate);
 #endif
 	__set_pfnblock_flags_mask(page, page_to_pfn(page), flags,
-				  MIGRATETYPE_AND_ISO_MASK);
+				  PAGEBLOCK_MIGRATETYPE_MASK | PAGEBLOCK_ISO_MASK);
 }
 
 #ifdef CONFIG_DEBUG_VM
@@ -2122,15 +2122,15 @@ static bool __move_freepages_block_isolate(struct zone *zone,
 	}
 
 move:
-	/* Use MIGRATETYPE_MASK to get non-isolate migratetype */
+	/* Use PAGEBLOCK_MIGRATETYPE_MASK to get non-isolate migratetype */
 	if (isolate) {
 		from_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page),
-						    MIGRATETYPE_MASK);
+						    PAGEBLOCK_MIGRATETYPE_MASK);
 		to_mt = MIGRATE_ISOLATE;
 	} else {
 		from_mt = MIGRATE_ISOLATE;
 		to_mt = __get_pfnblock_flags_mask(page, page_to_pfn(page),
-						  MIGRATETYPE_MASK);
+						  PAGEBLOCK_MIGRATETYPE_MASK);
 	}
 
 	__move_freepages_block(zone, start_pfn, from_mt, to_mt);

-- 
2.50.1