On Mon, 20 Dec 2010, Minchan Kim wrote:
> On Mon, Dec 20, 2010 at 7:10 AM, Jesper Juhl <jj@xxxxxxxxxxxxx> wrote:
> > Hi,
> >
> > The NODEMASK_ALLOC macro dynamically allocates memory for its second
> > argument ('nodes_allowed' in this context).
> > In nr_hugepages_store_common() we may abort early if strict_strtoul()
> > fails, but in that case we do not free the memory already allocated to
> > 'nodes_allowed', causing a memory leak.
> > This patch closes the leak by freeing the memory in the error path.
> >
> >
> > Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
> > ---
> > hugetlb.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > compile tested only
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 8585524..9fdcc35 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1439,8 +1439,10 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
> > NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
> >
> > err = strict_strtoul(buf, 10, &count);
> > - if (err)
> > + if (err) {
> > + kfree(nodes_allowed);
>
> Nice catch. But use NODEMASK_FREE. It might be not kmalloced object.
>
Right. I just checked the macro and it used kmalloc(), so I just wrote
kfree. But you are right, NODEMASK_FREE is the right thing to use here.
Updated patch below.
Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
---
hugetlb.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8585524..71e7886 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1439,8 +1439,10 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
err = strict_strtoul(buf, 10, &count);
- if (err)
+ if (err) {
+ NODEMASK_FREE(nodes_allowed);
return 0;
+ }
h = kobj_to_hstate(kobj, &nid);
if (nid == NUMA_NO_NODE) {
--
Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
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