vm: remove 'nr_accounted' calculations from the unmap_vmas() interfaces

The VM accounting makes no sense at this level, and half of the callers
didn't ever actually use the end result.  The only time we want to
unaccount the memory is when we actually remove the vma, so do the
accounting at that point instead.

This simplifies the interfaces (no need to pass down that silly page
counter to functions that really don't care), and also makes it much
more obvious what is actually going on: we do vm_[un]acct_memory() when
adding or removing the vma, not on random page walking.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 6 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 5880610..69a1889 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1889,15 +1889,20 @@ find_extend_vma(struct mm_struct * mm, unsigned long addr)
  */
 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
 {
+	unsigned long nr_accounted = 0;
+
 	/* Update high watermark before we lower total_vm */
 	update_hiwater_vm(mm);
 	do {
 		long nrpages = vma_pages(vma);
 
+		if (vma->vm_flags & VM_ACCOUNT)
+			nr_accounted += nrpages;
 		mm->total_vm -= nrpages;
 		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
 		vma = remove_vma(vma);
 	} while (vma);
+	vm_unacct_memory(nr_accounted);
 	validate_mm(mm);
 }
 
@@ -1912,13 +1917,11 @@ static void unmap_region(struct mm_struct *mm,
 {
 	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
 	struct mmu_gather tlb;
-	unsigned long nr_accounted = 0;
 
 	lru_add_drain();
 	tlb_gather_mmu(&tlb, mm, 0);
 	update_hiwater_rss(mm);
-	unmap_vmas(&tlb, vma, start, end, &nr_accounted);
-	vm_unacct_memory(nr_accounted);
+	unmap_vmas(&tlb, vma, start, end);
 	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
 				 next ? next->vm_start : 0);
 	tlb_finish_mmu(&tlb, start, end);
@@ -2305,8 +2308,7 @@ void exit_mmap(struct mm_struct *mm)
 	tlb_gather_mmu(&tlb, mm, 1);
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use -1 here to ensure all VMAs in the mm are unmapped */
-	unmap_vmas(&tlb, vma, 0, -1, &nr_accounted);
-	vm_unacct_memory(nr_accounted);
+	unmap_vmas(&tlb, vma, 0, -1);
 
 	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
 	tlb_finish_mmu(&tlb, 0, -1);
@@ -2315,8 +2317,12 @@ void exit_mmap(struct mm_struct *mm)
 	 * Walk the list again, actually closing and freeing it,
 	 * with preemption enabled, without holding any MM locks.
 	 */
-	while (vma)
+	while (vma) {
+		if (vma->vm_flags & VM_ACCOUNT)
+			nr_accounted += vma_pages(vma);
 		vma = remove_vma(vma);
+	}
+	vm_unacct_memory(nr_accounted);
 
 	BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
 }