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Message-ID: <20250604211427.1590859-1-ziy@nvidia.com>
Date: Wed, 4 Jun 2025 17:14:27 -0400
From: Zi Yan <ziy@...dia.com>
To: david@...hat.com
Cc: Liam.Howlett@...cle.com,
akpm@...ux-foundation.org,
isaacmanjarres@...gle.com,
jyescas@...gle.com,
kaleshsingh@...gle.com,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
lorenzo.stoakes@...cle.com,
masahiroy@...nel.org,
mhocko@...e.com,
minchan@...nel.org,
rppt@...nel.org,
surenb@...gle.com,
tjmercier@...gle.com,
vbabka@...e.cz,
ziy@...dia.com,
Anshuman Khandual <anshuman.khandual@....com>,
Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v2] mm: rename CONFIG_PAGE_BLOCK_ORDER to CONFIG_PAGE_BLOCK_MAX_ORDER.
The config is in fact an additional upper limit of pageblock_order, so
rename it to avoid confusion.
Signed-off-by: Zi Yan <ziy@...dia.com>
Acked-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
Acked-by: Juan Yescas <jyescas@...gle.com>
---
>From v1[1]:
1. used a new name: PAGE_BLOCK_MAX_ORDER,
2. added the missing PAGE_BLOCK_ORDER rename in mm/mm_init.c[2]
3. dropped the Fixes tag.
[1] https://lore.kernel.org/linux-mm/20250603154843.1565239-1-ziy@nvidia.com/
[2] https://lore.kernel.org/linux-mm/202506042058.XgvABCE0-lkp@intel.com/
include/linux/mmzone.h | 14 +++++++-------
include/linux/pageblock-flags.h | 8 ++++----
mm/Kconfig | 15 ++++++++-------
mm/mm_init.c | 2 +-
4 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 283913d42d7b..5bec8b1d0e66 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -38,19 +38,19 @@
#define NR_PAGE_ORDERS (MAX_PAGE_ORDER + 1)
/* Defines the order for the number of pages that have a migrate type. */
-#ifndef CONFIG_PAGE_BLOCK_ORDER
-#define PAGE_BLOCK_ORDER MAX_PAGE_ORDER
+#ifndef CONFIG_PAGE_BLOCK_MAX_ORDER
+#define PAGE_BLOCK_MAX_ORDER MAX_PAGE_ORDER
#else
-#define PAGE_BLOCK_ORDER CONFIG_PAGE_BLOCK_ORDER
-#endif /* CONFIG_PAGE_BLOCK_ORDER */
+#define PAGE_BLOCK_MAX_ORDER CONFIG_PAGE_BLOCK_MAX_ORDER
+#endif /* CONFIG_PAGE_BLOCK_MAX_ORDER */
/*
* The MAX_PAGE_ORDER, which defines the max order of pages to be allocated
- * by the buddy allocator, has to be larger or equal to the PAGE_BLOCK_ORDER,
+ * by the buddy allocator, has to be larger or equal to the PAGE_BLOCK_MAX_ORDER,
* which defines the order for the number of pages that can have a migrate type
*/
-#if (PAGE_BLOCK_ORDER > MAX_PAGE_ORDER)
-#error MAX_PAGE_ORDER must be >= PAGE_BLOCK_ORDER
+#if (PAGE_BLOCK_MAX_ORDER > MAX_PAGE_ORDER)
+#error MAX_PAGE_ORDER must be >= PAGE_BLOCK_MAX_ORDER
#endif
/*
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index e73a4292ef02..6297c6343c55 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -41,18 +41,18 @@ extern unsigned int pageblock_order;
* Huge pages are a constant size, but don't exceed the maximum allocation
* granularity.
*/
-#define pageblock_order MIN_T(unsigned int, HUGETLB_PAGE_ORDER, PAGE_BLOCK_ORDER)
+#define pageblock_order MIN_T(unsigned int, HUGETLB_PAGE_ORDER, PAGE_BLOCK_MAX_ORDER)
#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
#elif defined(CONFIG_TRANSPARENT_HUGEPAGE)
-#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, PAGE_BLOCK_ORDER)
+#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, PAGE_BLOCK_MAX_ORDER)
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
-/* If huge pages are not used, group by PAGE_BLOCK_ORDER */
-#define pageblock_order PAGE_BLOCK_ORDER
+/* If huge pages are not used, group by PAGE_BLOCK_MAX_ORDER */
+#define pageblock_order PAGE_BLOCK_MAX_ORDER
#endif /* CONFIG_HUGETLB_PAGE */
diff --git a/mm/Kconfig b/mm/Kconfig
index 65089552e124..3afac26d3594 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1017,8 +1017,8 @@ config ARCH_FORCE_MAX_ORDER
# the default page block order is MAX_PAGE_ORDER (10) as per
# include/linux/mmzone.h.
#
-config PAGE_BLOCK_ORDER
- int "Page Block Order"
+config PAGE_BLOCK_MAX_ORDER
+ int "Page Block Order Upper Limit"
range 1 10 if ARCH_FORCE_MAX_ORDER = 0
default 10 if ARCH_FORCE_MAX_ORDER = 0
range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0
@@ -1026,12 +1026,13 @@ config PAGE_BLOCK_ORDER
help
The page block order refers to the power of two number of pages that
are physically contiguous and can have a migrate type associated to
- them. The maximum size of the page block order is limited by
- ARCH_FORCE_MAX_ORDER.
+ them. The maximum size of the page block order is at least limited by
+ ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER.
- This config allows overriding the default page block order when the
- page block order is required to be smaller than ARCH_FORCE_MAX_ORDER
- or MAX_PAGE_ORDER.
+ This config adds a new upper limit of default page block
+ order when the page block order is required to be smaller than
+ ARCH_FORCE_MAX_ORDER/MAX_PAGE_ORDER or other limits
+ (see include/linux/pageblock-flags.h for details).
Reducing pageblock order can negatively impact THP generation
success rate. If your workloads use THP heavily, please use this
diff --git a/mm/mm_init.c b/mm/mm_init.c
index f2944748f526..02f41e2bdf60 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1509,7 +1509,7 @@ static inline void setup_usemap(struct zone *zone) {}
/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
void __init set_pageblock_order(void)
{
- unsigned int order = PAGE_BLOCK_ORDER;
+ unsigned int order = PAGE_BLOCK_MAX_ORDER;
/* Check that pageblock_nr_pages has not already been setup */
if (pageblock_order)
--
2.47.2
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