| Message ID | 20211113154412.91134-1-minhquangbui99@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | hugetlb: fix hugetlb cgroup refcounting during mremap | expand |
On Sat, 13 Nov 2021 22:44:10 +0700 Bui Quang Minh <minhquangbui99@gmail.com> 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.
On Mon, Nov 15, 2021 at 1:16 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Sat, 13 Nov 2021 22:44:10 +0700 Bui Quang Minh <minhquangbui99@gmail.com> 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@google.com>
Subject: Re: [PATCH] hugetlb: fix hugetlb cgroup refcounting during mremap To: Andrew Morton <akpm@linux-foundation.org>, Bui Quang Minh <minhquangbui99@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com>, Michal Hocko <mhocko@suse.com>, Muchun Song <songmuchun@bytedance.com>, Mina Almasry <almasrymina@google.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org Bcc: -=-=-=-=-=-=-=-=-=# Don't remove this line #=-=-=-=-=-=-=-=-=- On 11/15/21 1:16 PM, Andrew Morton wrote: > On Sat, 13 Nov 2021 22:44:10 +0700 Bui Quang Minh <minhquangbui99@gmail.com> 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() Good catch! Sorry I missed this in my review. Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com > 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. I may be confused, but 550a7d60bd5e35a was just merged in 5.16-rc1 so no need for cc:stable.
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h index c137396129db..ba025ae27882 100644 --- a/include/linux/hugetlb_cgroup.h +++ b/include/linux/hugetlb_cgroup.h @@ -128,6 +128,13 @@ static inline void resv_map_dup_hugetlb_cgroup_uncharge_info( css_get(resv_map->css); } +static inline void resv_map_put_hugetlb_cgroup_uncharge_info( + struct resv_map *resv_map) +{ + if (resv_map->css) + css_put(resv_map->css); +} + extern int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages, struct hugetlb_cgroup **ptr); extern int hugetlb_cgroup_charge_cgroup_rsvd(int idx, unsigned long nr_pages, @@ -211,6 +218,11 @@ static inline void resv_map_dup_hugetlb_cgroup_uncharge_info( { } +static inline void resv_map_put_hugetlb_cgroup_uncharge_info( + struct resv_map *resv_map) +{ +} + static inline int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages, struct hugetlb_cgroup **ptr) { diff --git a/mm/hugetlb.c b/mm/hugetlb.c index e09159c957e3..3a2479003ddf 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1037,8 +1037,10 @@ void clear_vma_resv_huge_pages(struct vm_area_struct *vma) */ struct resv_map *reservations = vma_resv_map(vma); - if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + if (reservations && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + resv_map_put_hugetlb_cgroup_uncharge_info(reservations); kref_put(&reservations->refs, resv_map_release); + } reset_vma_resv_huge_pages(vma); }
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() Fixes: 550a7d6 (mm, hugepages: add mremap() support for hugepage backed vma) Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com> --- include/linux/hugetlb_cgroup.h | 12 ++++++++++++ mm/hugetlb.c | 4 +++- 2 files changed, 15 insertions(+), 1 deletion(-)