mips, thp: remove infrastructure for handling splitting PMDs

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

pmdp_splitting_flush() is not needed too: on splitting PMD we will do
pmdp_clear_flush() + set_pte_at().  pmdp_clear_flush() will do IPI as
needed for fast_gup.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 5 insertions, 51 deletions

diff --git a/arch/mips/include/asm/pgtable-bits.h b/arch/mips/include/asm/pgtable-bits.h
index ff7ad91c85db..97b313882678 100644
--- a/arch/mips/include/asm/pgtable-bits.h
+++ b/arch/mips/include/asm/pgtable-bits.h
@@ -131,14 +131,12 @@
 /* Huge TLB page */
 #define _PAGE_HUGE_SHIFT        (_PAGE_MODIFIED_SHIFT + 1)
 #define _PAGE_HUGE              (1 << _PAGE_HUGE_SHIFT)
-#define _PAGE_SPLITTING_SHIFT   (_PAGE_HUGE_SHIFT + 1)
-#define _PAGE_SPLITTING         (1 << _PAGE_SPLITTING_SHIFT)
 #endif  /* CONFIG_64BIT && CONFIG_MIPS_HUGE_TLB_SUPPORT */
 
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
 /* XI - page cannot be executed */
-#ifdef _PAGE_SPLITTING_SHIFT
-#define _PAGE_NO_EXEC_SHIFT     (_PAGE_SPLITTING_SHIFT + 1)
+#ifdef _PAGE_HUGE_SHIFT
+#define _PAGE_NO_EXEC_SHIFT     (_PAGE_HUGE_SHIFT + 1)
 #else
 #define _PAGE_NO_EXEC_SHIFT     (_PAGE_MODIFIED_SHIFT + 1)
 #endif
@@ -153,8 +151,8 @@
 
 #if defined(_PAGE_NO_READ_SHIFT)
 #define _PAGE_GLOBAL_SHIFT      (_PAGE_NO_READ_SHIFT + 1)
-#elif defined(_PAGE_SPLITTING_SHIFT)
-#define _PAGE_GLOBAL_SHIFT      (_PAGE_SPLITTING_SHIFT + 1)
+#elif defined(_PAGE_HUGE_SHIFT)
+#define _PAGE_GLOBAL_SHIFT      (_PAGE_HUGE_SHIFT + 1)
 #else
 #define _PAGE_GLOBAL_SHIFT      (_PAGE_MODIFIED_SHIFT + 1)
 #endif
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 8957f15e21ec..6995b4a02e23 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -482,27 +482,9 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
         return pmd;
 }
 
-static inline int pmd_trans_splitting(pmd_t pmd)
-{
-        return !!(pmd_val(pmd) & _PAGE_SPLITTING);
-}
-
-static inline pmd_t pmd_mksplitting(pmd_t pmd)
-{
-        pmd_val(pmd) |= _PAGE_SPLITTING;
-
-        return pmd;
-}
-
 extern void set_pmd_at(struct mm_struct *mm, unsigned long addr,
                        pmd_t *pmdp, pmd_t pmd);
 
-#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-/* Extern to avoid header file madness */
-extern void pmdp_splitting_flush(struct vm_area_struct *vma,
-                                        unsigned long address,
-                                        pmd_t *pmdp);
-
 #define __HAVE_ARCH_PMD_WRITE
 static inline int pmd_write(pmd_t pmd)
 {
diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 36a35115dc2e..1afd87c999b0 100644
--- a/arch/mips/mm/gup.c
+++ b/arch/mips/mm/gup.c
@@ -107,18 +107,7 @@ 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_huge(pmd))) {
                         if (!gup_huge_pmd(pmd, addr, next, write, pages,nr))
diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index e8adc0069d66..ce4473e7c0d2 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -62,20 +62,6 @@ void pmd_init(unsigned long addr, unsigned long pagetable)
 }
 #endif
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-
-void pmdp_splitting_flush(struct vm_area_struct *vma,
-                         unsigned long address,
-                         pmd_t *pmdp)
-{
-        if (!pmd_trans_splitting(*pmdp)) {
-                pmd_t pmd = pmd_mksplitting(*pmdp);
-                set_pmd_at(vma->vm_mm, address, pmdp, pmd);
-        }
-}
-
-#endif
-
 pmd_t mk_pmd(struct page *page, pgprot_t prot)
 {
         pmd_t pmd;
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 32e0be27673f..482192cc8f2b 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -240,7 +240,6 @@ static void output_pgtable_bits_defines(void)
         pr_define("_PAGE_MODIFIED_SHIFT %d\n", _PAGE_MODIFIED_SHIFT);
 #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
         pr_define("_PAGE_HUGE_SHIFT %d\n", _PAGE_HUGE_SHIFT);
-        pr_define("_PAGE_SPLITTING_SHIFT %d\n", _PAGE_SPLITTING_SHIFT);
 #endif
 #ifdef CONFIG_CPU_MIPSR2
         if (cpu_has_rixi) {