Commit 6a60f1b3 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

mincore: cleanups 



This fixes some minor issues that bugged me while going over the code:

o adjust argument order of do_mincore() to match the syscall
o simplify range length calculation
o drop superfluous shift in huge tlb calculation, address is page aligned
o drop dead nr_huge calculation
o check pte_none() before pte_present()
o comment and whitespace fixes

No semantic changes intended.

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 c0ff7453

mm/mincore.c

+27 −49
Original line number Diff line number Diff line
@@ -54,7 +54,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff) 
 * all the arguments, we hold the mmap semaphore: we should

 * just return the amount of info we're asked for.

 */

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

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

{

	pgd_t *pgd;

	pud_t *pud;
@@ -64,35 +64,29 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag 
	unsigned long nr;

	int i;

	pgoff_t pgoff;

	struct vm_area_struct *vma = find_vma(current->mm, addr);

	struct vm_area_struct *vma;



	/*

	 * find_vma() didn't find anything above us, or we're

	 * in an unmapped hole in the address space: ENOMEM.

	 */

	vma = find_vma(current->mm, addr);

	if (!vma || addr < vma->vm_start)

		return -ENOMEM;



	nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);



#ifdef CONFIG_HUGETLB_PAGE

	if (is_vm_hugetlb_page(vma)) {

		struct hstate *h;

		unsigned long nr_huge;

		unsigned char present;



		i = 0;

		nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);

		h = hstate_vma(vma);

		nr_huge = ((addr + pages * PAGE_SIZE - 1) >> huge_page_shift(h))

			  - (addr >> huge_page_shift(h)) + 1;

		nr_huge = min(nr_huge,

			      (vma->vm_end - addr) >> huge_page_shift(h));

		while (1) {

			/* hugepage always in RAM for now,

			 * but generally it needs to be check */

			unsigned char present;

			/*

			 * Huge pages are always in RAM for now, but

			 * theoretically it needs to be checked.

			 */

			ptep = huge_pte_offset(current->mm,

					       addr & huge_page_mask(h));

			present = !!(ptep &&

				     !huge_pte_none(huge_ptep_get(ptep)));

			present = ptep && !huge_pte_none(huge_ptep_get(ptep));

			while (1) {

				vec[i++] = present;

				addr += PAGE_SIZE;
@@ -100,8 +94,7 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag 
				if (i == nr)

					return nr;

				/* check hugepage border */

				if (!((addr & ~huge_page_mask(h))

				      >> PAGE_SHIFT))

				if (!(addr & ~huge_page_mask(h)))

					break;

			}

		}
@@ -113,17 +106,7 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag 
	 * Calculate how many pages there are left in the last level of the

	 * PTE array for our address.

	 */

	nr = PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1));



	/*

	 * Don't overrun this vma

	 */

	nr = min(nr, (vma->vm_end - addr) >> PAGE_SHIFT);



	/*

	 * Don't return more than the caller asked for

	 */

	nr = min(nr, pages);

	nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)));



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

	if (pgd_none_or_clear_bad(pgd))
@@ -137,41 +120,36 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag 


	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);

	for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {

		unsigned char present;

		pte_t pte = *ptep;



		if (pte_present(pte)) {

			present = 1;



		} else if (pte_none(pte)) {

		if (pte_none(pte)) {

			if (vma->vm_file) {

				pgoff = linear_page_index(vma, addr);

				present = mincore_page(vma->vm_file->f_mapping,

				vec[i] = mincore_page(vma->vm_file->f_mapping,

						pgoff);

			} else

				present = 0;



		} else if (pte_file(pte)) {

				vec[i] = 0;

		} else if (pte_present(pte))

			vec[i] = 1;

		else if (pte_file(pte)) {

			pgoff = pte_to_pgoff(pte);

			present = mincore_page(vma->vm_file->f_mapping, pgoff);



			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);

		} else { /* pte is a swap entry */

			swp_entry_t entry = pte_to_swp_entry(pte);



			if (is_migration_entry(entry)) {

				/* migration entries are always uptodate */

				present = 1;

				vec[i] = 1;

			} else {

#ifdef CONFIG_SWAP

				pgoff = entry.val;

				present = mincore_page(&swapper_space, pgoff);

				vec[i] = mincore_page(&swapper_space, pgoff);

#else

				WARN_ON(1);

				present = 1;

				vec[i] = 1;

#endif

			}

		}



		vec[i] = present;

	}

	pte_unmap_unlock(ptep - 1, ptl);
@@ -247,7 +225,7 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len, 
		 * the temporary buffer size.

		 */

		down_read(&current->mm->mmap_sem);

		retval = do_mincore(start, tmp, min(pages, PAGE_SIZE));

		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);

		up_read(&current->mm->mmap_sem);



		if (retval <= 0)

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