On Wed, 5 Jan 2011 13:29:57 -0700
Eric B Munson <emunson@xxxxxxxxx> wrote:
> Huge pages with order >= MAX_ORDER must be allocated at boot via
> the kernel command line, they cannot be allocated or freed once
> the kernel is up and running. Currently we allow values to be
> written to the sysfs and sysctl files controling pool size for these
> huge page sizes. This patch makes the store functions for nr_hugepages
> and nr_overcommit_hugepages return -EINVAL when the pool for a
> page size >= MAX_ORDER is changed.
>
gack, you people keep on making me look at the hugetlb code :(
> index 5cb71a9..15bd633 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1443,6 +1443,12 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
> return -EINVAL;
Why do these functions do a `return 0' if strict_strtoul() failed?
>
> h = kobj_to_hstate(kobj, &nid);
> +
> + if (h->order >= MAX_ORDER) {
> + NODEMASK_FREE(nodes_allowed);
> + return -EINVAL;
> + }
Let's avoid having multiple unwind-and-return paths in a function,
please. it often leads to resource leaks and locking errors as the
code evolves.
--- a/mm/hugetlb.c~hugetlb-do-not-allow-pagesize-=-max_order-pool-adjustment-fix
+++ a/mm/hugetlb.c
@@ -1363,6 +1363,7 @@ static ssize_t nr_hugepages_show_common(
return sprintf(buf, "%lu\n", nr_huge_pages);
}
+
static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t len)
@@ -1375,15 +1376,14 @@ static ssize_t nr_hugepages_store_common
err = strict_strtoul(buf, 10, &count);
if (err) {
- NODEMASK_FREE(nodes_allowed);
- return 0;
+ err = 0; /* This seems wrong */
+ goto out;
}
h = kobj_to_hstate(kobj, &nid);
-
if (h->order >= MAX_ORDER) {
- NODEMASK_FREE(nodes_allowed);
- return -EINVAL;
+ err = -EINVAL;
+ goto out;
}
if (nid == NUMA_NO_NODE) {
@@ -1411,6 +1411,9 @@ static ssize_t nr_hugepages_store_common
NODEMASK_FREE(nodes_allowed);
return len;
+out:
+ NODEMASK_FREE(nodes_allowed);
+ return err;
}
static ssize_t nr_hugepages_show(struct kobject *kobj,
_
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