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mincore: cleanups

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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: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2010-05-24 14:32:09 -07:00 committed by Linus Torvalds
parent c0ff7453bb
commit 6a60f1b358
1 changed files with 27 additions and 49 deletions
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74
mm/mincore.c
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@ -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 * all the arguments, we hold the mmap semaphore: we should
* just return the amount of info we're asked for. * 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; pgd_t *pgd;
pud_t *pud; pud_t *pud;
@ -64,35 +64,29 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag
unsigned long nr; unsigned long nr;
int i; int i;
pgoff_t pgoff; pgoff_t pgoff;
struct vm_area_struct *vma = find_vma(current->mm, addr); struct vm_area_struct *vma;
/* vma = find_vma(current->mm, addr);
* find_vma() didn't find anything above us, or we're
* in an unmapped hole in the address space: ENOMEM.
*/
if (!vma || addr < vma->vm_start) if (!vma || addr < vma->vm_start)
return -ENOMEM; return -ENOMEM;
nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
#ifdef CONFIG_HUGETLB_PAGE #ifdef CONFIG_HUGETLB_PAGE
if (is_vm_hugetlb_page(vma)) { if (is_vm_hugetlb_page(vma)) {
struct hstate *h; struct hstate *h;
unsigned long nr_huge;
unsigned char present;
i = 0; i = 0;
nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
h = hstate_vma(vma); 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) { while (1) {
/* hugepage always in RAM for now, unsigned char present;
* but generally it needs to be check */ /*
* Huge pages are always in RAM for now, but
* theoretically it needs to be checked.
*/
ptep = huge_pte_offset(current->mm, ptep = huge_pte_offset(current->mm,
addr & huge_page_mask(h)); addr & huge_page_mask(h));
present = !!(ptep && present = ptep && !huge_pte_none(huge_ptep_get(ptep));
!huge_pte_none(huge_ptep_get(ptep)));
while (1) { while (1) {
vec[i++] = present; vec[i++] = present;
addr += PAGE_SIZE; addr += PAGE_SIZE;
@ -100,8 +94,7 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag
if (i == nr) if (i == nr)
return nr; return nr;
/* check hugepage border */ /* check hugepage border */
if (!((addr & ~huge_page_mask(h)) if (!(addr & ~huge_page_mask(h)))
>> PAGE_SHIFT))
break; 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 * Calculate how many pages there are left in the last level of the
* PTE array for our address. * PTE array for our address.
*/ */
nr = PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)); nr = min(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);
pgd = pgd_offset(vma->vm_mm, addr); pgd = pgd_offset(vma->vm_mm, addr);
if (pgd_none_or_clear_bad(pgd)) if (pgd_none_or_clear_bad(pgd))
@ -137,43 +120,38 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag
ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) { for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {
unsigned char present;
pte_t pte = *ptep; pte_t pte = *ptep;
if (pte_present(pte)) { if (pte_none(pte)) {
present = 1;
} else if (pte_none(pte)) {
if (vma->vm_file) { if (vma->vm_file) {
pgoff = linear_page_index(vma, addr); pgoff = linear_page_index(vma, addr);
present = mincore_page(vma->vm_file->f_mapping, vec[i] = mincore_page(vma->vm_file->f_mapping,
pgoff); pgoff);
} else } else
present = 0; vec[i] = 0;
} else if (pte_present(pte))
} else if (pte_file(pte)) { vec[i] = 1;
else if (pte_file(pte)) {
pgoff = pte_to_pgoff(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 */ } else { /* pte is a swap entry */
swp_entry_t entry = pte_to_swp_entry(pte); swp_entry_t entry = pte_to_swp_entry(pte);
if (is_migration_entry(entry)) { if (is_migration_entry(entry)) {
/* migration entries are always uptodate */ /* migration entries are always uptodate */
present = 1; vec[i] = 1;
} else { } else {
#ifdef CONFIG_SWAP #ifdef CONFIG_SWAP
pgoff = entry.val; pgoff = entry.val;
present = mincore_page(&swapper_space, pgoff); vec[i] = mincore_page(&swapper_space, pgoff);
#else #else
WARN_ON(1); WARN_ON(1);
present = 1; vec[i] = 1;
#endif #endif
} }
} }
vec[i] = present;
} }
pte_unmap_unlock(ptep-1, ptl); pte_unmap_unlock(ptep - 1, ptl);
return nr; return nr;
@ -247,7 +225,7 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
* the temporary buffer size. * the temporary buffer size.
*/ */
down_read(&current->mm->mmap_sem); 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); up_read(&current->mm->mmap_sem);
if (retval <= 0) if (retval <= 0)