[RFC PATCH 2/7] mm: set pageblock_order to the max of HUGETLB_PAGE_ORDER and MAX_ORDER-1

Zi Yan
2021-05-06T15:26:18Z

From: Zi Yan <ziy@nvidia.com>

As MAX_ORDER can be increased to larger than hugetlb page orders,
pageblock_order will be limited at HUGETLB_PAGE_ORDER. It is not
ideal for anti-fragmentation for allocating pages from buddy allocator
with MAX_ORDER > HUGETLB_PAGE_ORDER. Make pageblock_order a variable and
set it to the max of HUGETLB_PAGE_ORDER, MAX_ORDER - 1.

Remove HUGETLB_PAGE_SIZE_VARIABLE as HUGETLB_PAGE does the same thing
now.

Export pageblock_order since virtio-mem module needs it.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
arch/ia64/Kconfig | 1 -
arch/powerpc/Kconfig | 1 -
include/linux/pageblock-flags.h | 9 ---------
mm/Kconfig | 7 -------
mm/page_alloc.c | 13 +++++++------
mm/sparse.c | 2 +-
6 files changed, 8 insertions(+), 25 deletions(-)

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 279252e3e0f7..c6a150cde668 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -34,7 +34,6 @@ config IA64
select TTY
select HAVE_ARCH_TRACEHOOK
select HAVE_VIRT_CPU_ACCOUNTING
- select HUGETLB_PAGE_SIZE_VARIABLE if HUGETLB_PAGE
select VIRT_TO_BUS
select GENERIC_IRQ_PROBE
select GENERIC_PENDING_IRQ if SMP
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 8926461d25b2..9f27c131ed45 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -238,7 +238,6 @@ config PPC
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
- select HUGETLB_PAGE_SIZE_VARIABLE if PPC_BOOK3S_64 && HUGETLB_PAGE
select MMU_GATHER_RCU_TABLE_FREE
select MMU_GATHER_PAGE_SIZE
select HAVE_REGS_AND_STACK_ACCESS_API
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index fff52ad370c1..efab85e2ae1c 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -30,18 +30,9 @@ enum pageblock_bits {

#ifdef CONFIG_HUGETLB_PAGE

-#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
-
/* Huge page sizes are variable */
extern unsigned int pageblock_order;

-#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
-
-/* Huge pages are a constant size */
-#define pageblock_order HUGETLB_PAGE_ORDER
-
-#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
-
#else /* CONFIG_HUGETLB_PAGE */

/* If huge pages are not used, group by MAX_ORDER_NR_PAGES */
diff --git a/mm/Kconfig b/mm/Kconfig
index a8a367c30053..3466c3d09295 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -284,13 +284,6 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
config ARCH_ENABLE_THP_MIGRATION
bool

-config HUGETLB_PAGE_SIZE_VARIABLE
- def_bool n
- help
- Allows the pageblock_order value to be dynamic instead of just standard
- HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
- on a platform.
-
config CONTIG_ALLOC
def_bool (MEMORY_ISOLATION && COMPACTION) || CMA

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a2fe714aed93..72bb4a300e03 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -256,8 +256,9 @@ bool pm_suspended_storage(void)
}
#endif /* CONFIG_PM_SLEEP */

-#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+#ifdef CONFIG_HUGETLB_PAGE
unsigned int pageblock_order __read_mostly;
+EXPORT_SYMBOL_GPL(pageblock_order);
#endif

static void __free_pages_ok(struct page *page, unsigned int order,
@@ -7057,7 +7058,7 @@ static void __ref setup_usemap(struct zone *zone)
static inline void setup_usemap(struct zone *zone) {}
#endif /* CONFIG_SPARSEMEM */

-#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
+#ifdef CONFIG_HUGETLB_PAGE

/* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */
void __init set_pageblock_order(void)
@@ -7068,7 +7069,7 @@ void __init set_pageblock_order(void)
if (pageblock_order)
return;

- if (HPAGE_SHIFT > PAGE_SHIFT)
+ if ((HPAGE_SHIFT > PAGE_SHIFT) && (HUGETLB_PAGE_ORDER > (MAX_ORDER - 1)))
order = HUGETLB_PAGE_ORDER;
else
order = MAX_ORDER - 1;
@@ -7080,10 +7081,10 @@ void __init set_pageblock_order(void)
*/
pageblock_order = order;
}
-#else /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+#else /* CONFIG_HUGETLB_PAGE */

/*
- * When CONFIG_HUGETLB_PAGE_SIZE_VARIABLE is not set, set_pageblock_order()
+ * When CONFIG_HUGETLB_PAGE is not set, set_pageblock_order()
* is unused as pageblock_order is set at compile-time. See
* include/linux/pageblock-flags.h for the values of pageblock_order based on
* the kernel config
@@ -7092,7 +7093,7 @@ void __init set_pageblock_order(void)
{
}

-#endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */
+#endif /* CONFIG_HUGETLB_PAGE */

static unsigned long __init calc_memmap_size(unsigned long spanned_pages,
unsigned long present_pages)
diff --git a/mm/sparse.c b/mm/sparse.c
index 7637208b8874..1c2957807882 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -583,7 +583,7 @@ void __init sparse_init(void)
pnum_begin = first_present_section_nr();
nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));

- /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
+ /* Setup pageblock_order for HUGETLB_PAGE */
set_pageblock_order();

for_each_present_section_nr(pnum_begin + 1, pnum_end) {
--
2.30.2