mm/mempolicy.c: remove BUG_ON() checks for VMA inside mpol_misplaced()

VMA and its address bounds checks are too late in this function.  They
must have been verified earlier in the page fault sequence.  Hence just
remove them.

Link: http://lkml.kernel.org/r/20170901130137.7617-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mempolicy.c

@@ -2233,17 +2233,12 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
 	int polnid = -1;
 	int ret = -1;
 
-	BUG_ON(!vma);
-
 	pol = get_vma_policy(vma, addr);
 	if (!(pol->flags & MPOL_F_MOF))
 		goto out;
 
 	switch (pol->mode) {
 	case MPOL_INTERLEAVE:
-		BUG_ON(addr >= vma->vm_end);
-		BUG_ON(addr < vma->vm_start);
-
 		pgoff = vma->vm_pgoff;
 		pgoff += (addr - vma->vm_start) >> PAGE_SHIFT;
 		polnid = offset_il_node(pol, pgoff);