Commit e48293fd authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mincore: do nested page table walks 



Do page table walks with the well-known nested loops we use in several
other places already.

This avoids doing full page table walks after every pte range and also
allows to handle unmapped areas bigger than one pte range in one go.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 25ef0e50

mm/mincore.c

+58 −17
Original line number Diff line number Diff line
@@ -144,6 +144,60 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
	pte_unmap_unlock(ptep - 1, ptl);

}



static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,

			unsigned long addr, unsigned long end,

			unsigned char *vec)

{

	unsigned long next;

	pmd_t *pmd;



	pmd = pmd_offset(pud, addr);

	do {

		next = pmd_addr_end(addr, end);

		if (pmd_none_or_clear_bad(pmd))

			mincore_unmapped_range(vma, addr, next, vec);

		else

			mincore_pte_range(vma, pmd, addr, next, vec);

		vec += (next - addr) >> PAGE_SHIFT;

	} while (pmd++, addr = next, addr != end);

}



static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,

			unsigned long addr, unsigned long end,

			unsigned char *vec)

{

	unsigned long next;

	pud_t *pud;



	pud = pud_offset(pgd, addr);

	do {

		next = pud_addr_end(addr, end);

		if (pud_none_or_clear_bad(pud))

			mincore_unmapped_range(vma, addr, next, vec);

		else

			mincore_pmd_range(vma, pud, addr, next, vec);

		vec += (next - addr) >> PAGE_SHIFT;

	} while (pud++, addr = next, addr != end);

}



static void mincore_page_range(struct vm_area_struct *vma,

			unsigned long addr, unsigned long end,

			unsigned char *vec)

{

	unsigned long next;

	pgd_t *pgd;



	pgd = pgd_offset(vma->vm_mm, addr);

	do {

		next = pgd_addr_end(addr, end);

		if (pgd_none_or_clear_bad(pgd))

			mincore_unmapped_range(vma, addr, next, vec);

		else

			mincore_pud_range(vma, pgd, addr, next, vec);

		vec += (next - addr) >> PAGE_SHIFT;

	} while (pgd++, addr = next, addr != end);

}



/*

 * Do a chunk of "sys_mincore()". We've already checked

 * all the arguments, we hold the mmap semaphore: we should
@@ -151,9 +205,6 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 
 */

static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)

{

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	struct vm_area_struct *vma;

	unsigned long end;
@@ -170,21 +221,11 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v 


	end = pmd_addr_end(addr, end);



	pgd = pgd_offset(vma->vm_mm, addr);

	if (pgd_none_or_clear_bad(pgd))

		goto none_mapped;

	pud = pud_offset(pgd, addr);

	if (pud_none_or_clear_bad(pud))

		goto none_mapped;

	pmd = pmd_offset(pud, addr);

	if (pmd_none_or_clear_bad(pmd))

		goto none_mapped;



	mincore_pte_range(vma, pmd, addr, end, vec);

	return (end - addr) >> PAGE_SHIFT;

	if (is_vm_hugetlb_page(vma))

		mincore_hugetlb_page_range(vma, addr, end, vec);

	else

		mincore_page_range(vma, addr, end, vec);



none_mapped:

	mincore_unmapped_range(vma, addr, end, vec);

	return (end - addr) >> PAGE_SHIFT;

}

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