From f4ea9362930131faa98dc544ece0386925c98527 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Tue, 30 Jul 2024 20:49:43 +0200 Subject: [PATCH] mm: vrealloc: properly document __GFP_ZERO behavior 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. Link: https://lkml.kernel.org/r/20240730185049.6244-4-dakr@kernel.org Signed-off-by: Danilo Krummrich Signed-off-by: Andrew Morton --- mm/vmalloc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 4339c56be3c8..c63f74bf2e7a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4036,12 +4036,17 @@ 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. * -- 2.50.1