mm: Count the number of pages affected in change_protection()
This will be used for three kinds of purposes:
- to optimize mprotect()
- to speed up working set scanning for working set areas that
have not been touched
- to more accurately scan per real working set
No change in functionality from this patch.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 59a0059..712895e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3014,7 +3014,7 @@
return i ? i : -EFAULT;
}
-void hugetlb_change_protection(struct vm_area_struct *vma,
+unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
unsigned long address, unsigned long end, pgprot_t newprot)
{
struct mm_struct *mm = vma->vm_mm;
@@ -3022,6 +3022,7 @@
pte_t *ptep;
pte_t pte;
struct hstate *h = hstate_vma(vma);
+ unsigned long pages = 0;
BUG_ON(address >= end);
flush_cache_range(vma, address, end);
@@ -3032,12 +3033,15 @@
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
- if (huge_pmd_unshare(mm, &address, ptep))
+ if (huge_pmd_unshare(mm, &address, ptep)) {
+ pages++;
continue;
+ }
if (!huge_pte_none(huge_ptep_get(ptep))) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
+ pages++;
}
}
spin_unlock(&mm->page_table_lock);
@@ -3049,6 +3053,8 @@
*/
flush_tlb_range(vma, start, end);
mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
+
+ return pages << h->order;
}
int hugetlb_reserve_pages(struct inode *inode,