mm: mlock_vma_pages_range() never return negative value

Currently, mlock_vma_pages_range() never return negative value.  Then, we
can remove some worthless error check.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamewzawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mmap.c

@@ -1265,12 +1265,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	mm->total_vm += len >> PAGE_SHIFT;
 	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
 	if (vm_flags & VM_LOCKED) {
-		/*
-		 * makes pages present; downgrades, drops, reacquires mmap_sem
-		 */
 		long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
-		if (nr_pages < 0)
-			return nr_pages;	/* vma gone! */
 		mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
 	} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
 		make_pages_present(addr, addr + len);
@@ -1754,8 +1749,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
 	if (!prev || expand_stack(prev, addr))
 		return NULL;
 	if (prev->vm_flags & VM_LOCKED) {
-		if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
-			return NULL;	/* vma gone! */
+		mlock_vma_pages_range(prev, addr, prev->vm_end);
 	}
 	return prev;
 }
@@ -1783,8 +1777,7 @@ find_extend_vma(struct mm_struct * mm, unsigned long addr)
 	if (expand_stack(vma, addr))
 		return NULL;
 	if (vma->vm_flags & VM_LOCKED) {
-		if (mlock_vma_pages_range(vma, addr, start) < 0)
-			return NULL;	/* vma gone! */
+		mlock_vma_pages_range(vma, addr, start);
 	}
 	return vma;
 }