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Commit 36eaff33 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm, ksm: convert write_protect_page() to use page_vma_mapped_walk() 

For consistency, it worth converting all page_check_address() to
page_vma_mapped_walk(), so we could drop the former.

Link: http://lkml.kernel.org/r/20170129173858.45174-9-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c7ab0d2f

mm/ksm.c

+18 −16
Original line number Diff line number Diff line
@@ -856,33 +856,35 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, 
			      pte_t *orig_pte)

{

	struct mm_struct *mm = vma->vm_mm;

	unsigned long addr;

	pte_t *ptep;

	spinlock_t *ptl;

	struct page_vma_mapped_walk pvmw = {

		.page = page,

		.vma = vma,

	};

	int swapped;

	int err = -EFAULT;

	unsigned long mmun_start;	/* For mmu_notifiers */

	unsigned long mmun_end;		/* For mmu_notifiers */



	addr = page_address_in_vma(page, vma);

	if (addr == -EFAULT)

	pvmw.address = page_address_in_vma(page, vma);

	if (pvmw.address == -EFAULT)

		goto out;



	BUG_ON(PageTransCompound(page));



	mmun_start = addr;

	mmun_end   = addr + PAGE_SIZE;

	mmun_start = pvmw.address;

	mmun_end   = pvmw.address + PAGE_SIZE;

	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);



	ptep = page_check_address(page, mm, addr, &ptl, 0);

	if (!ptep)

	if (!page_vma_mapped_walk(&pvmw))

		goto out_mn;

	if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))

		goto out_unlock;



	if (pte_write(*ptep) || pte_dirty(*ptep)) {

	if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {

		pte_t entry;



		swapped = PageSwapCache(page);

		flush_cache_page(vma, addr, page_to_pfn(page));

		flush_cache_page(vma, pvmw.address, page_to_pfn(page));

		/*

		 * Ok this is tricky, when get_user_pages_fast() run it doesn't

		 * take any lock, therefore the check that we are going to make
@@ -892,25 +894,25 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, 
		 * this assure us that no O_DIRECT can happen after the check

		 * or in the middle of the check.

		 */

		entry = ptep_clear_flush_notify(vma, addr, ptep);

		entry = ptep_clear_flush_notify(vma, pvmw.address, pvmw.pte);

		/*

		 * Check that no O_DIRECT or similar I/O is in progress on the

		 * page

		 */

		if (page_mapcount(page) + 1 + swapped != page_count(page)) {

			set_pte_at(mm, addr, ptep, entry);

			set_pte_at(mm, pvmw.address, pvmw.pte, entry);

			goto out_unlock;

		}

		if (pte_dirty(entry))

			set_page_dirty(page);

		entry = pte_mkclean(pte_wrprotect(entry));

		set_pte_at_notify(mm, addr, ptep, entry);

		set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);

	}

	*orig_pte = *ptep;

	*orig_pte = *pvmw.pte;

	err = 0;



out_unlock:

	pte_unmap_unlock(ptep, ptl);

	page_vma_mapped_walk_done(&pvmw);

out_mn:

	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

out: