mm/vmalloc: check various alignments when debugging

Before we did not guarantee a free block with lowest start address for
allocations with alignment >= PAGE_SIZE.  Because an alignment overhead
was included into a search length like below:

     length = size + align - 1;

doing so we make sure that a bigger block would fit after applying an
alignment adjustment.  Now there is no such limitation, i.e.  any
alignment that user wants to apply will result to a lowest address of
returned free area.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Oleksiy Avramchenko <[email protected]>
Cc: Ping Fang <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: urezki

mm/vmalloc.c

@@ -1269,7 +1269,7 @@ find_vmap_lowest_linear_match(unsigned long size,
 }
 
 static void
-find_vmap_lowest_match_check(unsigned long size)
+find_vmap_lowest_match_check(unsigned long size, unsigned long align)
 {
 	struct vmap_area *va_1, *va_2;
 	unsigned long vstart;
@@ -1278,8 +1278,8 @@ find_vmap_lowest_match_check(unsigned long size)
 	get_random_bytes(&rnd, sizeof(rnd));
 	vstart = VMALLOC_START + rnd;
 
-	va_1 = find_vmap_lowest_match(size, 1, vstart);
-	va_2 = find_vmap_lowest_linear_match(size, 1, vstart);
+	va_1 = find_vmap_lowest_match(size, align, vstart);
+	va_2 = find_vmap_lowest_linear_match(size, align, vstart);
 
 	if (va_1 != va_2)
 		pr_emerg("not lowest: t: 0x%p, l: 0x%p, v: 0x%lx\n",
@@ -1458,7 +1458,7 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
 		return vend;
 
 #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
-	find_vmap_lowest_match_check(size);
+	find_vmap_lowest_match_check(size, align);
 #endif
 
 	return nva_start_addr;