I've realized that there's no need in do_huge_pmd_wp_zero_page_fallback().
We can just split zero page with split_huge_page_pmd() and return
VM_FAULT_FALLBACK. handle_pte_fault() will handle write-protection fault
for us.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 79 ++------------------------------------------------------
1 file changed, 2 insertions(+), 77 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 65a88bef8694..436fd2b51284 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -941,81 +941,6 @@ unlock:
spin_unlock(ptl);
}
-static int do_huge_pmd_wp_zero_page_fallback(struct mm_struct *mm,
- struct vm_area_struct *vma, unsigned long address,
- pmd_t *pmd, pmd_t orig_pmd, unsigned long haddr)
-{
- spinlock_t *ptl;
- pgtable_t pgtable;
- pmd_t _pmd;
- struct page *page;
- int i, ret = 0;
- unsigned long mmun_start; /* For mmu_notifiers */
- unsigned long mmun_end; /* For mmu_notifiers */
-
- page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
- if (!page) {
- ret |= VM_FAULT_OOM;
- goto out;
- }
-
- if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
- put_page(page);
- ret |= VM_FAULT_OOM;
- goto out;
- }
-
- clear_user_highpage(page, address);
- __SetPageUptodate(page);
-
- mmun_start = haddr;
- mmun_end = haddr + HPAGE_PMD_SIZE;
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
-
- ptl = pmd_lock(mm, pmd);
- if (unlikely(!pmd_same(*pmd, orig_pmd)))
- goto out_free_page;
-
- pmdp_clear_flush(vma, haddr, pmd);
- /* leave pmd empty until pte is filled */
-
- pgtable = pgtable_trans_huge_withdraw(mm, pmd);
- pmd_populate(mm, &_pmd, pgtable);
-
- for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
- pte_t *pte, entry;
- if (haddr == (address & PAGE_MASK)) {
- entry = mk_pte(page, vma->vm_page_prot);
- entry = maybe_mkwrite(pte_mkdirty(entry), vma);
- page_add_new_anon_rmap(page, vma, haddr);
- } else {
- entry = pfn_pte(my_zero_pfn(haddr), vma->vm_page_prot);
- entry = pte_mkspecial(entry);
- }
- pte = pte_offset_map(&_pmd, haddr);
- VM_BUG_ON(!pte_none(*pte));
- set_pte_at(mm, haddr, pte, entry);
- pte_unmap(pte);
- }
- smp_wmb(); /* make pte visible before pmd */
- pmd_populate(mm, pmd, pgtable);
- spin_unlock(ptl);
- put_huge_zero_page();
- inc_mm_counter(mm, MM_ANONPAGES);
-
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
-
- ret |= VM_FAULT_WRITE;
-out:
- return ret;
-out_free_page:
- spin_unlock(ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- mem_cgroup_uncharge_page(page);
- put_page(page);
- goto out;
-}
-
static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long address,
@@ -1161,8 +1086,8 @@ alloc:
if (unlikely(!new_page)) {
if (!page) {
- ret = do_huge_pmd_wp_zero_page_fallback(mm, vma,
- address, pmd, orig_pmd, haddr);
+ split_huge_page_pmd(vma, address, pmd);
+ ret |= VM_FAULT_FALLBACK;
} else {
ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
pmd, orig_pmd, page, haddr);
--
1.8.5.2
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