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Commit e9b71ca9 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm, thp: drop do_huge_pmd_wp_zero_page_fallback() 



I've realized that there's no need for 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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3bb97794

mm/huge_memory.c

+2 −77
Original line number Diff line number Diff line
@@ -941,81 +941,6 @@ void huge_pmd_set_accessed(struct mm_struct *mm, 
	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 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 


	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);