mm: make vb_alloc() more foolproof
If someone calls vb_alloc() (or vm_map_ram() for that matter) to allocate
0 bytes (0 pages), get_order() returns BITS_PER_LONG - PAGE_CACHE_SHIFT
and interesting stuff happens. So make debugging such problems easier and
warn about 0-size allocation.
[akpm@linux-foundation.org: use WARN_ON-return-value feature]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7e25ee3..2bb90b1 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -904,6 +904,14 @@
BUG_ON(size & ~PAGE_MASK);
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+ if (WARN_ON(size == 0)) {
+ /*
+ * Allocating 0 bytes isn't what caller wants since
+ * get_order(0) returns funny result. Just warn and terminate
+ * early.
+ */
+ return NULL;
+ }
order = get_order(size);
again: