[PATCHv3 16/24] x86, thp: remove infrastructure for handling splitting PMDs

Kirill A. Shutemov
2015-02-12T16:19:46Z

With new refcounting we don't need to mark PMDs splitting. Let's drop
code to handle this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/include/asm/pgtable.h | 9 ---------
arch/x86/include/asm/pgtable_types.h | 2 --
arch/x86/mm/gup.c | 13 +------------
arch/x86/mm/pgtable.c | 14 --------------
4 files changed, 1 insertion(+), 37 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 9d0ade00923e..c6243e9f1666 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -158,11 +158,6 @@ static inline int pmd_large(pmd_t pte)
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static inline int pmd_trans_splitting(pmd_t pmd)
-{
- return pmd_val(pmd) & _PAGE_SPLITTING;
-}
-
static inline int pmd_trans_huge(pmd_t pmd)
{
return pmd_val(pmd) & _PAGE_PSE;
@@ -792,10 +787,6 @@ extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);

-#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-extern void pmdp_splitting_flush(struct vm_area_struct *vma,
- unsigned long addr, pmd_t *pmdp);
-
#define __HAVE_ARCH_PMD_WRITE
static inline int pmd_write(pmd_t pmd)
{
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 8c7c10802e9c..706f2f06d5b0 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -22,7 +22,6 @@
#define _PAGE_BIT_PAT_LARGE 12 /* On 2MB or 1GB pages */
#define _PAGE_BIT_SPECIAL _PAGE_BIT_SOFTW1
#define _PAGE_BIT_CPA_TEST _PAGE_BIT_SOFTW1
-#define _PAGE_BIT_SPLITTING _PAGE_BIT_SOFTW2 /* only valid on a PSE pmd */
#define _PAGE_BIT_HIDDEN _PAGE_BIT_SOFTW3 /* hidden by kmemcheck */
#define _PAGE_BIT_SOFT_DIRTY _PAGE_BIT_SOFTW3 /* software dirty tracking */
#define _PAGE_BIT_NX 63 /* No execute: only valid after cpuid check */
@@ -46,7 +45,6 @@
#define _PAGE_PAT_LARGE (_AT(pteval_t, 1) << _PAGE_BIT_PAT_LARGE)
#define _PAGE_SPECIAL (_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL)
#define _PAGE_CPA_TEST (_AT(pteval_t, 1) << _PAGE_BIT_CPA_TEST)
-#define _PAGE_SPLITTING (_AT(pteval_t, 1) << _PAGE_BIT_SPLITTING)
#define __HAVE_ARCH_PTE_SPECIAL

#ifdef CONFIG_KMEMCHECK
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 62a887a3cf50..49bbbc57603b 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -157,18 +157,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
pmd_t pmd = *pmdp;

next = pmd_addr_end(addr, end);
- /*
- * The pmd_trans_splitting() check below explains why
- * pmdp_splitting_flush has to flush the tlb, to stop
- * this gup-fast code from running while we set the
- * splitting bit in the pmd. Returning zero will take
- * the slow path that will call wait_split_huge_page()
- * if the pmd is still in splitting state. gup-fast
- * can't because it has irq disabled and
- * wait_split_huge_page() would never return as the
- * tlb flush IPI wouldn't run.
- */
- if (pmd_none(pmd) || pmd_trans_splitting(pmd))
+ if (pmd_none(pmd))
return 0;
if (unlikely(pmd_large(pmd) || !pmd_present(pmd))) {
/*
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 7b22adaad4f1..a4c75bdee21d 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -433,20 +433,6 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,

return young;
}
-
-void pmdp_splitting_flush(struct vm_area_struct *vma,
- unsigned long address, pmd_t *pmdp)
-{
- int set;
- VM_BUG_ON(address & ~HPAGE_PMD_MASK);
- set = !test_and_set_bit(_PAGE_BIT_SPLITTING,
- (unsigned long *)pmdp);
- if (set) {
- pmd_update(vma->vm_mm, address, pmdp);
- /* need tlb flush only to serialize against gup-fast */
- flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
- }
-}
#endif

/**
--
2.1.4