[PATCH 3/4] mm: vrealloc: properly document __GFP_ZERO behavior

[Danilo Krummrich]

Properly document that if __GFP_ZERO logic is requested, callers must
ensure that, starting with the initial memory allocation, every
subsequent call to this API for the same memory allocation is flagged
with __GFP_ZERO. Otherwise, it is possible that __GFP_ZERO is not fully
honored by this API.

Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 mm/vmalloc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 6a2fef6378e4..48cc10dd06c0 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4043,12 +4043,17 @@ EXPORT_SYMBOL(vzalloc_node_noprof);
  * @size: the size to reallocate
  * @flags: the flags for the page level allocator
  *
- * The contents of the object pointed to are preserved up to the lesser of the
- * new and old size (__GFP_ZERO flag is effectively ignored).
- *
  * If @p is %NULL, vrealloc() behaves exactly like vmalloc(). If @size is 0 and
  * @p is not a %NULL pointer, the object pointed to is freed.
  *
+ * If __GFP_ZERO logic is requested, callers must ensure that, starting with the
+ * initial memory allocation, every subsequent call to this API for the same
+ * memory allocation is flagged with __GFP_ZERO. Otherwise, it is possible that
+ * __GFP_ZERO is not fully honored by this API.
+ *
+ * In any case, the contents of the object pointed to are preserved up to the
+ * lesser of the new and old sizes.
+ *
  * This function must not be called concurrently with itself or vfree() for the
  * same memory allocation.
  *
-- 
2.45.2