We are going to decouple splitting THP PMD from splitting underlying
compound page.

This patch renames split_huge_page_pmd*() functions to split_huge_pmd*()
to reflect the fact that it doesn't imply page splitting, only PMD.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 arch/powerpc/mm/subpage-prot.c |  2 +-
 arch/x86/kernel/vm86_32.c      |  6 +++++-
 include/linux/huge_mm.h        |  8 ++------
 mm/huge_memory.c               | 33 +++++++++++++--------------------
 mm/madvise.c                   |  2 +-
 mm/memory.c                    |  2 +-
 mm/mempolicy.c                 |  2 +-
 mm/mprotect.c                  |  2 +-
 mm/mremap.c                    |  2 +-
 mm/pagewalk.c                  |  2 +-
 10 files changed, 27 insertions(+), 34 deletions(-)

diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c
index fa9fb5b4c66c..d5543514c1df 100644
--- a/arch/powerpc/mm/subpage-prot.c
+++ b/arch/powerpc/mm/subpage-prot.c
@@ -135,7 +135,7 @@ static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long 
addr,
                                  unsigned long end, struct mm_walk *walk)
 {
        struct vm_area_struct *vma = walk->vma;
-       split_huge_page_pmd(vma, addr, pmd);
+       split_huge_pmd(vma, pmd, addr);
        return 0;
 }
 
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index e8edcf52e069..883160599965 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -182,7 +182,11 @@ static void mark_screen_rdonly(struct mm_struct *mm)
        if (pud_none_or_clear_bad(pud))
                goto out;
        pmd = pmd_offset(pud, 0xA0000);
-       split_huge_page_pmd_mm(mm, 0xA0000, pmd);
+
+       if (pmd_trans_huge(*pmd)) {
+               struct vm_area_struct *vma = find_vma(mm, 0xA0000);
+               split_huge_pmd(vma, pmd, 0xA0000);
+       }
        if (pmd_none_or_clear_bad(pmd))
                goto out;
        pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 44a840a53974..34bbf769d52e 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -104,7 +104,7 @@ static inline int split_huge_page(struct page *page)
 }
 extern void __split_huge_page_pmd(struct vm_area_struct *vma,
                unsigned long address, pmd_t *pmd);
-#define split_huge_page_pmd(__vma, __address, __pmd)                   \
+#define split_huge_pmd(__vma, __pmd, __address)                                
\
        do {                                                            \
                pmd_t *____pmd = (__pmd);                               \
                if (unlikely(pmd_trans_huge(*____pmd)))                 \
@@ -119,8 +119,6 @@ extern void __split_huge_page_pmd(struct vm_area_struct 
*vma,
                BUG_ON(pmd_trans_splitting(*____pmd) ||                 \
                       pmd_trans_huge(*____pmd));                       \
        } while (0)
-extern void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
-               pmd_t *pmd);
 #if HPAGE_PMD_ORDER >= MAX_ORDER
 #error "hugepages can't be allocated by the buddy allocator"
 #endif
@@ -187,11 +185,9 @@ static inline int split_huge_page(struct page *page)
 {
        return 0;
 }
-#define split_huge_page_pmd(__vma, __address, __pmd)   \
-       do { } while (0)
 #define wait_split_huge_page(__anon_vma, __pmd)        \
        do { } while (0)
-#define split_huge_page_pmd_mm(__mm, __address, __pmd) \
+#define split_huge_pmd(__vma, __pmd, __address)        \
        do { } while (0)
 static inline int hugepage_madvise(struct vm_area_struct *vma,
                                   unsigned long *vm_flags, int advice)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9d18e9bafb26..d447afc039f9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1127,13 +1127,13 @@ alloc:
 
        if (unlikely(!new_page)) {
                if (!page) {
-                       split_huge_page_pmd(vma, address, pmd);
+                       split_huge_pmd(vma, pmd, address);
                        ret |= VM_FAULT_FALLBACK;
                } else {
                        ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
                                        pmd, orig_pmd, page, haddr);
                        if (ret & VM_FAULT_OOM) {
-                               split_huge_page(page);
+                               split_huge_pmd(vma, pmd, address);
                                ret |= VM_FAULT_FALLBACK;
                        }
                        put_user_huge_page(page);
@@ -1146,10 +1146,10 @@ alloc:
                                           GFP_TRANSHUGE, &memcg))) {
                put_page(new_page);
                if (page) {
-                       split_huge_page(page);
+                       split_huge_pmd(vma, pmd, address);
                        put_user_huge_page(page);
                } else
-                       split_huge_page_pmd(vma, address, pmd);
+                       split_huge_pmd(vma, pmd, address);
                ret |= VM_FAULT_FALLBACK;
                count_vm_event(THP_FAULT_FALLBACK);
                goto out;
@@ -1709,17 +1709,7 @@ again:
                goto again;
 }
 
-void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
-               pmd_t *pmd)
-{
-       struct vm_area_struct *vma;
-
-       vma = find_vma(mm, address);
-       BUG_ON(vma == NULL);
-       split_huge_page_pmd(vma, address, pmd);
-}
-
-static void split_huge_page_address(struct mm_struct *mm,
+static void split_huge_pmd_address(struct vm_area_struct *vma,
                                    unsigned long address)
 {
        pgd_t *pgd;
@@ -1728,7 +1718,7 @@ static void split_huge_page_address(struct mm_struct *mm,
 
        VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
 
-       pgd = pgd_offset(mm, address);
+       pgd = pgd_offset(vma->vm_mm, address);
        if (!pgd_present(*pgd))
                return;
 
@@ -1739,11 +1729,14 @@ static void split_huge_page_address(struct mm_struct 
*mm,
        pmd = pmd_offset(pud, address);
        if (!pmd_present(*pmd))
                return;
+
+       if (!pmd_trans_huge(*pmd))
+               return;
        /*
         * Caller holds the mmap_sem write mode, so a huge pmd cannot
         * materialize from under us.
         */
-       split_huge_page_pmd_mm(mm, address, pmd);
+       __split_huge_page_pmd(vma, address, pmd);
 }
 
 static int __split_huge_page_splitting(struct page *page,
@@ -3005,7 +2998,7 @@ void __vma_adjust_trans_huge(struct vm_area_struct *vma,
        if (start & ~HPAGE_PMD_MASK &&
            (start & HPAGE_PMD_MASK) >= vma->vm_start &&
            (start & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
-               split_huge_page_address(vma->vm_mm, start);
+               split_huge_pmd_address(vma, start);
 
        /*
         * If the new end address isn't hpage aligned and it could
@@ -3015,7 +3008,7 @@ void __vma_adjust_trans_huge(struct vm_area_struct *vma,
        if (end & ~HPAGE_PMD_MASK &&
            (end & HPAGE_PMD_MASK) >= vma->vm_start &&
            (end & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= vma->vm_end)
-               split_huge_page_address(vma->vm_mm, end);
+               split_huge_pmd_address(vma, end);
 
        /*
         * If we're also updating the vma->vm_next->vm_start, if the new
@@ -3029,6 +3022,6 @@ void __vma_adjust_trans_huge(struct vm_area_struct *vma,
                if (nstart & ~HPAGE_PMD_MASK &&
                    (nstart & HPAGE_PMD_MASK) >= next->vm_start &&
                    (nstart & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE <= next->vm_end)
-                       split_huge_page_address(next->vm_mm, nstart);
+                       split_huge_pmd_address(next, nstart);
        }
 }
diff --git a/mm/madvise.c b/mm/madvise.c
index 6d0fcb8921c2..c0bbe52eb3bf 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -279,7 +279,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long 
addr,
        next = pmd_addr_end(addr, end);
        if (pmd_trans_huge(*pmd)) {
                if (next - addr != HPAGE_PMD_SIZE)
-                       split_huge_page_pmd(vma, addr, pmd);
+                       split_huge_pmd(vma, pmd, addr);
                else if (!madvise_free_huge_pmd(tlb, vma, pmd, addr))
                        goto next;
                /* fall through */
diff --git a/mm/memory.c b/mm/memory.c
index 343f800dff25..6f030a3a7636 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1204,7 +1204,7 @@ static inline unsigned long zap_pmd_range(struct 
mmu_gather *tlb,
                                        BUG();
                                }
 #endif
-                               split_huge_page_pmd(vma, addr, pmd);
+                               split_huge_pmd(vma, pmd, addr);
                        } else if (zap_huge_pmd(tlb, vma, pmd, addr))
                                goto next;
                        /* fall through */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4721046a134a..eeec3dd199f5 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -493,7 +493,7 @@ static int queue_pages_pte_range(pmd_t *pmd, unsigned long 
addr,
        pte_t *pte;
        spinlock_t *ptl;
 
-       split_huge_page_pmd(vma, addr, pmd);
+       split_huge_pmd(vma, pmd, addr);
        if (pmd_trans_unstable(pmd))
                return 0;
 
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 44727811bf4c..81632238f857 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -155,7 +155,7 @@ static inline unsigned long change_pmd_range(struct 
vm_area_struct *vma,
 
                if (pmd_trans_huge(*pmd)) {
                        if (next - addr != HPAGE_PMD_SIZE)
-                               split_huge_page_pmd(vma, addr, pmd);
+                               split_huge_pmd(vma, pmd, addr);
                        else {
                                int nr_ptes = change_huge_pmd(vma, pmd, addr,
                                                newprot, prot_numa);
diff --git a/mm/mremap.c b/mm/mremap.c
index 57dadc025c64..95ac595de7da 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -208,7 +208,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                                need_flush = true;
                                continue;
                        } else if (!err) {
-                               split_huge_page_pmd(vma, old_addr, old_pmd);
+                               split_huge_pmd(vma, old_pmd, old_addr);
                        }
                        VM_BUG_ON(pmd_trans_huge(*old_pmd));
                }
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 75c1f2878519..5b23a69439c8 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -58,7 +58,7 @@ again:
                if (!walk->pte_entry)
                        continue;
 
-               split_huge_page_pmd_mm(walk->mm, addr, pmd);
+               split_huge_pmd(walk->vma, pmd, addr);
                if (pmd_trans_unstable(pmd))
                        goto again;
                err = walk_pte_range(pmd, addr, next, walk);
-- 
2.1.4

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