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.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
mm/vmalloc.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2aad499..bebee70 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -904,6 +904,15 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
BUG_ON(size & ~PAGE_MASK);
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
+ if (size == 0) {
+ /*
+ * Allocating 0 bytes isn't what caller wants since
+ * get_order(0) returns funny result. Just warn and terminate
+ * early.
+ */
+ WARN_ON(1);
+ return NULL;
+ }
order = get_order(size);
again:
--
1.7.1
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