Re: [PATCH] hugetlb: fix hugetlb cgroup refcounting during mremap

[Mina Almasry]

On Mon, Nov 15, 2021 at 1:16 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> On Sat, 13 Nov 2021 22:44:10 +0700 Bui Quang Minh <minhquangbui99@xxxxxxxxx> wrote:
>
> > When hugetlb_vm_op_open() is called during copy_vma(), we may take the
> > reference to resv_map->css. Later, when clearing the reservation pointer
> > of old_vma after transferring it to new_vma, we forget to drop the
> > reference to resv_map->css. This leads to a reference leak of css.
> >
> > Fixes this by adding a check to drop reservation css  reference in
> > clear_vma_resv_huge_pages()
>
> Thanks.  I added cc:stable to this (550a7d60bd5e35a was merged a year
> ago) and I've queued it for 5.16-rc2, pending suitable reviewer feedback.
>

Thanks,

Reviewed-by: Mina Almasry <almasrymina@xxxxxxxxxx>