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Date: Tue, 23 Mar 2010 15:34:58 +0100
From: Johannes Weiner <hannes@...xchg.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>
Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [patch 1/5] 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: Johannes Weiner <hannes@...xchg.org>
---
mm/mincore.c | 76 ++++++++++++++++++++-------------------------------------
1 files changed, 27 insertions(+), 49 deletions(-)
diff --git a/mm/mincore.c b/mm/mincore.c
index fe360ab..c35f8f0 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -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))
@@ -138,43 +121,38 @@ static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pag
ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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,
- pgoff);
+ 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);
+ pte_unmap_unlock(ptep - 1, ptl);
return nr;
@@ -248,7 +226,7 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
* the temporary buffer size.
*/
down_read(¤t->mm->mmap_sem);
- retval = do_mincore(start, tmp, min(pages, PAGE_SIZE));
+ retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
up_read(¤t->mm->mmap_sem);
if (retval <= 0)
--
1.7.0.2
--
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