On Wed, 5 Jan 2011 13:16:33 -0700
Eric B Munson <emunson@xxxxxxxxx> wrote:
> When parsing changes to the huge page pool sizes made from userspace
> via the sysfs interface, bogus input values are being covered up
> by nr_hugepages_store_common and nr_overcommit_hugepages_store
> returning 0 when strict_strtoul returns an error. This can cause an
> infinite loop in the nr_hugepages_store code. This patch changes
> the return value for these functions to -EINVAL when strict_strtoul
> returns an error.
>
ah, OK, there we are.
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 8585524..5cb71a9 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1440,7 +1440,7 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
>
> err = strict_strtoul(buf, 10, &count);
> if (err)
> - return 0;
> + return -EINVAL;
>
> h = kobj_to_hstate(kobj, &nid);
> if (nid == NUMA_NO_NODE) {
> @@ -1519,7 +1519,7 @@ static ssize_t nr_overcommit_hugepages_store(struct kobject *kobj,
>
> err = strict_strtoul(buf, 10, &input);
> if (err)
> - return 0;
> + return -EINVAL;
>
> spin_lock(&hugetlb_lock);
> h->nr_overcommit_huge_pages = input;
strict_strtoul() returns an errno - thise code should propagate it, not
overwrite it.
Here's what I ended up with:
diff -puN mm/hugetlb.c~fix-handling-of-parse-errors-in-sysfs mm/hugetlb.c
--- a/mm/hugetlb.c~fix-handling-of-parse-errors-in-sysfs
+++ a/mm/hugetlb.c
@@ -1375,10 +1375,8 @@ static ssize_t nr_hugepages_store_common
NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
err = strict_strtoul(buf, 10, &count);
- if (err) {
- err = 0; /* This seems wrong */
+ if (err)
goto out;
- }
h = kobj_to_hstate(kobj, &nid);
if (h->order >= MAX_ORDER) {
@@ -1468,7 +1466,7 @@ static ssize_t nr_overcommit_hugepages_s
err = strict_strtoul(buf, 10, &input);
if (err)
- return 0;
+ return err;
spin_lock(&hugetlb_lock);
h->nr_overcommit_huge_pages = input;
_
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