The preparation of splitting huge PMD mapping of vmemmap pages is ready,
so switch the mapping from PTE to PMD.
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 7 -------
arch/x86/mm/init_64.c | 8 ++------
include/linux/hugetlb.h | 25 ++++++-------------------
mm/memory_hotplug.c | 2 +-
4 files changed, 9 insertions(+), 33 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index db1ef6739613..a01aadafee38 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1599,13 +1599,6 @@
enabled.
Allows heavy hugetlb users to free up some more
memory (6 * PAGE_SIZE for each 2MB hugetlb page).
- This feauture is not free though. Large page
- tables are not used to back vmemmap pages which
- can lead to a performance degradation for some
- workloads. Also there will be memory allocation
- required when hugetlb pages are freed from the
- pool which can lead to corner cases under heavy
- memory pressure.
Format: { on | off (default) }
on: enable the feature
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 9d9d18d0c2a1..65ea58527176 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -34,7 +34,6 @@
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
-#include <linux/hugetlb.h>
#include <asm/processor.h>
#include <asm/bios_ebda.h>
@@ -1610,8 +1609,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));
- if ((is_hugetlb_free_vmemmap_enabled() && !altmap) ||
- end - start < PAGES_PER_SECTION * sizeof(struct page))
+ if (end - start < PAGES_PER_SECTION * sizeof(struct page))
err = vmemmap_populate_basepages(start, end, node, NULL);
else if (boot_cpu_has(X86_FEATURE_PSE))
err = vmemmap_populate_hugepages(start, end, node, altmap);
@@ -1639,8 +1637,6 @@ void register_page_bootmem_memmap(unsigned long section_nr,
pmd_t *pmd;
unsigned int nr_pmd_pages;
struct page *page;
- bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) ||
- is_hugetlb_free_vmemmap_enabled();
for (; addr < end; addr = next) {
pte_t *pte = NULL;
@@ -1666,7 +1662,7 @@ void register_page_bootmem_memmap(unsigned long section_nr,
}
get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
- if (base_mapping) {
+ if (!boot_cpu_has(X86_FEATURE_PSE)) {
next = (addr + PAGE_SIZE) & PAGE_MASK;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd))
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index c27a299c4211..2b46e6494114 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -907,20 +907,6 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
}
#endif
-#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
-extern bool hugetlb_free_vmemmap_enabled;
-
-static inline bool is_hugetlb_free_vmemmap_enabled(void)
-{
- return hugetlb_free_vmemmap_enabled;
-}
-#else
-static inline bool is_hugetlb_free_vmemmap_enabled(void)
-{
- return false;
-}
-#endif
-
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
@@ -1080,13 +1066,14 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr
pte_t *ptep, pte_t pte, unsigned long sz)
{
}
-
-static inline bool is_hugetlb_free_vmemmap_enabled(void)
-{
- return false;
-}
#endif /* CONFIG_HUGETLB_PAGE */
+#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+extern bool hugetlb_free_vmemmap_enabled;
+#else
+#define hugetlb_free_vmemmap_enabled false
+#endif
+
static inline spinlock_t *huge_pte_lock(struct hstate *h,
struct mm_struct *mm, pte_t *pte)
{
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index d96a3c7551c8..9d8a551c08d5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1056,7 +1056,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size)
* populate a single PMD.
*/
return memmap_on_memory &&
- !is_hugetlb_free_vmemmap_enabled() &&
+ !hugetlb_free_vmemmap_enabled &&
IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) &&
size == memory_block_size_bytes() &&
IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
--
2.11.0
