On 8/31/26 3:53 PM, Muchun Song wrote:
The section-based vmemmap optimization infrastructure is still guarded by
CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP, but it also can be used by device
DAX. Introduce CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION as a common config
for the shared infrastructure.
Select the new option from HUGETLB_PAGE_OPTIMIZE_VMEMMAP and from
DEV_DAX when the architecture opts in to DAX vmemmap optimization, and
use it to guard the generic sparse-vmemmap state and helpers.
Signed-off-by: Muchun Song <[email protected]>
---
arch/x86/entry/vdso/vdso32/fake_32bit_build.h | 2 +-
drivers/dax/Kconfig | 1 +
fs/Kconfig | 1 +
include/linux/mm.h | 3 +++
include/linux/mmzone.h | 13 +++++++------
include/linux/page-flags.h | 5 ++---
mm/Kconfig | 3 +++
mm/sparse.h | 4 ++--
8 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/arch/x86/entry/vdso/vdso32/fake_32bit_build.h
b/arch/x86/entry/vdso/vdso32/fake_32bit_build.h
index bc3e549795c3..5f8424eade2b 100644
--- a/arch/x86/entry/vdso/vdso32/fake_32bit_build.h
+++ b/arch/x86/entry/vdso/vdso32/fake_32bit_build.h
@@ -11,7 +11,7 @@
#undef CONFIG_PGTABLE_LEVELS
#undef CONFIG_ILLEGAL_POINTER_VALUE
#undef CONFIG_SPARSEMEM_VMEMMAP
-#undef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#undef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
#undef CONFIG_NR_CPUS
#undef CONFIG_PARAVIRT_XXL
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index 602f9a0839a9..85ad4c135cdd 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -8,6 +8,7 @@ if DAX
config DEV_DAX
tristate "Device DAX: direct access mapping device"
depends on TRANSPARENT_HUGEPAGE
+ select SPARSEMEM_VMEMMAP_OPTIMIZATION if ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
help
Support raw access to differentiated (persistence, bandwidth,
latency...) memory via an mmap(2) capable character
diff --git a/fs/Kconfig b/fs/Kconfig
index d1c210c6508f..9b32ce79cc80 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -278,6 +278,7 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP
def_bool HUGETLB_PAGE
depends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
depends on SPARSEMEM_VMEMMAP
+ select SPARSEMEM_VMEMMAP_OPTIMIZATION
config HUGETLB_PMD_PAGE_TABLE_SHARING
def_bool HUGETLB_PAGE
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a9fbe26536f4..edadd7549b72 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -5188,6 +5188,9 @@ static inline bool __vmemmap_can_optimize(struct
vmem_altmap *altmap,
unsigned long nr_pages;
unsigned long nr_vmemmap_pages;
+ if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
+ return false;
+
if (!pgmap || !is_power_of_2(sizeof(struct page)))
return false;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index c9ae7991a8b2..e9b54ea0eff0 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -102,9 +102,9 @@
*
* HVO which is only active if the size of struct page is a power of 2.
*/
-#define MAX_FOLIO_VMEMMAP_ALIGN \
- (IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP) && \
- is_power_of_2(sizeof(struct page)) ? \
+#define MAX_FOLIO_VMEMMAP_ALIGN \
+ (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION) && \
+ is_power_of_2(sizeof(struct page)) ? \
MAX_FOLIO_NR_PAGES * sizeof(struct page) : 0)
/* The number of retained vmemmap pages with HVO enabled. */
@@ -116,7 +116,8 @@
#define __VMEMMAP_OPTIMIZATION_NR_ORDERS \
(MAX_FOLIO_ORDER - VMEMMAP_OPTIMIZATION_MIN_ORDER + 1)
#define VMEMMAP_OPTIMIZATION_NR_ORDERS \
- (__VMEMMAP_OPTIMIZATION_NR_ORDERS > 0 ?
__VMEMMAP_OPTIMIZATION_NR_ORDERS : 0)
+ ((__VMEMMAP_OPTIMIZATION_NR_ORDERS > 0 && \
+ IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION)) ?
__VMEMMAP_OPTIMIZATION_NR_ORDERS : 0)
enum migratetype {
MIGRATE_UNMOVABLE,
@@ -1155,7 +1156,7 @@ struct zone {
/* Zone statistics */
atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS];
atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS];
-#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
struct page *vmemmap_tails[VMEMMAP_OPTIMIZATION_NR_ORDERS];
#endif
} ____cacheline_internodealigned_in_smp;
@@ -2019,7 +2020,7 @@ struct mem_section {
unsigned long section_mem_map;
struct mem_section_usage *usage;
-#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
/*
* Normally, sections hold regular (order-0) pages. However, for
* sections with HVO enabled, this tracks the compound page order
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index ae2ebaed6d4d..de3c06062bc6 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -208,14 +208,13 @@ enum pageflags {
static __always_inline bool compound_info_has_mask(void)
{
/*
- * Limit mask usage to HugeTLB vmemmap optimization (HVO) where it
- * makes a difference.
+ * Limit mask usage to HVO where it makes a difference.
*
* The approach with mask would work in the wider set of conditions,
* but it requires validating that struct pages are naturally aligned
* for all orders up to the MAX_FOLIO_ORDER, which can be tricky.
*/
- if (!IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP))
+ if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
return false;
return is_power_of_2(sizeof(struct page));
diff --git a/mm/Kconfig b/mm/Kconfig
index c1ddf59c0d71..b5f8372cd164 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -461,6 +461,9 @@ config SPARSEMEM_VMEMMAP
pfn_to_page and page_to_pfn operations. This is the most
efficient option when sufficient kernel resources are available.
+config SPARSEMEM_VMEMMAP_OPTIMIZATION
+ bool
As sashiko was concerned about [1], it seems we need to add
depends on SPARSEMEM_VMEMMAP
here.
Apart from that, LGTM. With this fix included:
Acked-by: Qi Zheng <[email protected]>
Thanks,
Qi
[1].
https://sashiko.dev/#/patchset/20260831075342.57563-1-songmuchun%40bytedance.com
+
#
# Select this config option from the architecture Kconfig, if it is preferred
# to enable the feature of HugeTLB/dev_dax vmemmap optimization.
diff --git a/mm/sparse.h b/mm/sparse.h
index 049272aba84e..b408d15baf7b 100644
--- a/mm/sparse.h
+++ b/mm/sparse.h
@@ -10,7 +10,7 @@
#include <linux/mmzone.h>
-#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
static inline unsigned int section_order(const struct mem_section *section)
{
return section->order;
@@ -72,7 +72,7 @@ static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
static inline bool vmemmap_optimizable_order(unsigned int order)
{
- if (!IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP))
+ if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
return false;
if (!is_power_of_2(sizeof(struct page)))
