On Thu, 6 Jan 2011 11:04:39 +0100
Michal Hocko <mhocko@xxxxxxx> wrote:
> NODEMASK_ALLOC can use kmalloc if nodemask_t > 256 bytes so it might
> fail with NULL as a result. Let's check the resulting variable and
> fail with -ENOMEM if NODEMASK_ALLOC failed.
>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
> ---
> mm/hugetlb.c | 18 +++++++++++++++---
> 1 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 4c0606c..21f31b2 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1439,14 +1439,19 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
> struct hstate *h;
> NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
>
> + if (!nodes_allowed) {
> + err = -ENOMEM;
> + goto out;
> + }
Looks good to me. I was going to complain that it adds extra unneeded
instructions in the case where the nodemasks are allocated on the
stack. But it appears that gcc assumes that stack-based variables
cannot have address zero, so if gcc sees this:
{
nodemask_t foo;
if (!&foo) {
stuff
}
}
if just removes it all for us.
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