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Message-ID: <20250530162227.715551-3-ziy@nvidia.com>
Date: Fri, 30 May 2025 12:22:23 -0400
From: Zi Yan <ziy@...dia.com>
To: David Hildenbrand <david@...hat.com>,
Johannes Weiner <hannes@...xchg.org>,
Vlastimil Babka <vbabka@...e.cz>,
linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Oscar Salvador <osalvador@...e.de>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Mel Gorman <mgorman@...hsingularity.net>,
Suren Baghdasaryan <surenb@...gle.com>,
Michal Hocko <mhocko@...e.com>,
Brendan Jackman <jackmanb@...gle.com>,
Richard Chang <richardycc@...gle.com>,
linux-kernel@...r.kernel.org,
Zi Yan <ziy@...dia.com>
Subject: [PATCH v6 2/6] mm/page_isolation: make page isolation a standalone bit.
During page isolation, the original migratetype is overwritten, since
MIGRATE_* are enums and stored in pageblock bitmaps. Change
MIGRATE_ISOLATE to be stored a standalone bit, PB_migrate_isolate, like
PB_compact_skip, so that migratetype is not lost during pageblock
isolation.
Signed-off-by: Zi Yan <ziy@...dia.com>
---
include/linux/mmzone.h | 3 +++
include/linux/page-isolation.h | 16 ++++++++++++++++
include/linux/pageblock-flags.h | 14 ++++++++++++++
mm/page_alloc.c | 27 ++++++++++++++++++++++++---
4 files changed, 57 insertions(+), 3 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 392a03e37610..0a5cdc52b405 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -79,6 +79,9 @@ enum migratetype {
* __free_pageblock_cma() function.
*/
MIGRATE_CMA,
+ __MIGRATE_TYPE_END = MIGRATE_CMA,
+#else
+ __MIGRATE_TYPE_END = MIGRATE_HIGHATOMIC,
#endif
#ifdef CONFIG_MEMORY_ISOLATION
MIGRATE_ISOLATE, /* can't allocate from here */
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 277d8d92980c..fc021d3f95ca 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -11,6 +11,12 @@ static inline bool is_migrate_isolate(int migratetype)
{
return migratetype == MIGRATE_ISOLATE;
}
+#define get_pageblock_isolate(page) \
+ get_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate)
+#define clear_pageblock_isolate(page) \
+ clear_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate)
+#define set_pageblock_isolate(page) \
+ set_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate)
#else
static inline bool is_migrate_isolate_page(struct page *page)
{
@@ -20,6 +26,16 @@ static inline bool is_migrate_isolate(int migratetype)
{
return false;
}
+static inline bool get_pageblock_isolate(struct page *page)
+{
+ return false;
+}
+static inline void clear_pageblock_isolate(struct page *page)
+{
+}
+static inline void set_pageblock_isolate(struct page *page)
+{
+}
#endif
#define MEMORY_OFFLINE 0x1
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 451b351c689e..1cf5f0fbd627 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -21,6 +21,13 @@ enum pageblock_bits {
/* 3 bits required for migrate types */
PB_compact_skip,/* If set the block is skipped by compaction */
+#ifdef CONFIG_MEMORY_ISOLATION
+ /*
+ * Pageblock isolation is represented with a separate bit, so that
+ * the migratetype of a block is not overwritten by isolation.
+ */
+ PB_migrate_isolate, /* If set the block is isolated */
+#endif
/*
* Assume the bits will always align on a word. If this assumption
* changes then get/set pageblock needs updating.
@@ -32,6 +39,13 @@ enum pageblock_bits {
#define MIGRATETYPE_MASK ((1UL << (PB_migrate_end + 1)) - 1)
+#ifdef CONFIG_MEMORY_ISOLATION
+#define MIGRATETYPE_AND_ISO_MASK \
+ (((1UL << (PB_migrate_end + 1)) - 1) | BIT(PB_migrate_isolate))
+#else
+#define MIGRATETYPE_AND_ISO_MASK MIGRATETYPE_MASK
+#endif
+
#if defined(CONFIG_HUGETLB_PAGE)
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 74cb7696e527..5de23eba0db8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -365,8 +365,12 @@ get_pfnblock_bitmap_bitidx(const struct page *page, unsigned long pfn,
unsigned long *bitmap;
unsigned long word_bitidx;
+#ifdef CONFIG_MEMORY_ISOLATION
+ BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 8);
+#else
BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
- BUILD_BUG_ON(MIGRATE_TYPES > (1 << PB_migratetype_bits));
+#endif
+ BUILD_BUG_ON(__MIGRATE_TYPE_END >= (1 << PB_migratetype_bits));
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
bitmap = get_pageblock_bitmap(page, pfn);
@@ -439,7 +443,16 @@ 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)
{
- return __get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
+ unsigned long mask = MIGRATETYPE_AND_ISO_MASK;
+ unsigned long flags;
+
+ flags = __get_pfnblock_flags_mask(page, pfn, mask);
+
+#ifdef CONFIG_MEMORY_ISOLATION
+ if (flags & BIT(PB_migrate_isolate))
+ return MIGRATE_ISOLATE;
+#endif
+ return flags & MIGRATETYPE_MASK;
}
/**
@@ -519,8 +532,16 @@ __always_inline void set_pageblock_migratetype(struct page *page,
migratetype < MIGRATE_PCPTYPES))
migratetype = MIGRATE_UNMOVABLE;
+#ifdef CONFIG_MEMORY_ISOLATION
+ if (migratetype == MIGRATE_ISOLATE) {
+ set_pfnblock_bit(page, page_to_pfn(page), PB_migrate_isolate);
+ return;
+ }
+ /* MIGRATETYPE_AND_ISO_MASK clears PB_migrate_isolate if it is set */
+#endif
__set_pfnblock_flags_mask(page, page_to_pfn(page),
- (unsigned long)migratetype, MIGRATETYPE_MASK);
+ (unsigned long)migratetype,
+ MIGRATETYPE_AND_ISO_MASK);
}
#ifdef CONFIG_DEBUG_VM
--
2.47.2
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