diff options
author | Mike Kravetz <mike.kravetz@oracle.com> | 2021-09-02 14:58:53 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-18 13:40:36 +0200 |
commit | e1fa3b2b60abb9f43b937741e27c6531ef4cbef9 (patch) | |
tree | 437d5ad77f806eae0e9b5fd4e778e43a00420d3f /mm/hugetlb.c | |
parent | 27dd91221b3f714f315c6e6b8f59924fbdd4c331 (diff) |
hugetlb: fix hugetlb cgroup refcounting during vma split
commit 09a26e832705fdb7a9484495b71a05e0bbc65207 upstream.
Guillaume Morin reported hitting the following WARNING followed by GPF or
NULL pointer deference either in cgroups_destroy or in the kill_css path.:
percpu ref (css_release) <= 0 (-1) after switching to atomic
WARNING: CPU: 23 PID: 130 at lib/percpu-refcount.c:196 percpu_ref_switch_to_atomic_rcu+0x127/0x130
CPU: 23 PID: 130 Comm: ksoftirqd/23 Kdump: loaded Tainted: G O 5.10.60 #1
RIP: 0010:percpu_ref_switch_to_atomic_rcu+0x127/0x130
Call Trace:
rcu_core+0x30f/0x530
rcu_core_si+0xe/0x10
__do_softirq+0x103/0x2a2
run_ksoftirqd+0x2b/0x40
smpboot_thread_fn+0x11a/0x170
kthread+0x10a/0x140
ret_from_fork+0x22/0x30
Upon further examination, it was discovered that the css structure was
associated with hugetlb reservations.
For private hugetlb mappings the vma points to a reserve map that
contains a pointer to the css. At mmap time, reservations are set up
and a reference to the css is taken. This reference is dropped in the
vma close operation; hugetlb_vm_op_close. However, if a vma is split no
additional reference to the css is taken yet hugetlb_vm_op_close will be
called twice for the split vma resulting in an underflow.
Fix by taking another reference in hugetlb_vm_op_open. Note that the
reference is only taken for the owner of the reserve map. In the more
common fork case, the pointer to the reserve map is cleared for
non-owning vmas.
Link: https://lkml.kernel.org/r/20210830215015.155224-1-mike.kravetz@oracle.com
Fixes: e9fe92ae0cd2 ("hugetlb_cgroup: add reservation accounting for private mappings")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Guillaume Morin <guillaume@morinfr.org>
Suggested-by: Guillaume Morin <guillaume@morinfr.org>
Tested-by: Guillaume Morin <guillaume@morinfr.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r-- | mm/hugetlb.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index fa6b0ac6c280..6e92ab0ae070 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3659,8 +3659,10 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma) * after this open call completes. It is therefore safe to take a * new reference here without additional locking. */ - if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) + if (resv && is_vma_resv_set(vma, HPAGE_RESV_OWNER)) { + resv_map_dup_hugetlb_cgroup_uncharge_info(resv); kref_get(&resv->refs); + } } static void hugetlb_vm_op_close(struct vm_area_struct *vma) |