From: Greg Thelen gthelen@google.com
5.10 stable commit 2b00b2a0e642 ("writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs") is a backport of upstream 6.3 commit 1ba1199ec574.
In the 5.10 stable commit backport percpu_ref_exit() is called twice: first in cgwb_release_workfn() and then in cgwb_free_rcu(). The 2nd call is benign as percpu_ref_exit() internally detects there's nothing to do.
This fixes an non-upstream issue that only applies to 5.10.y.
Fixes: 2b00b2a0e642 ("writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs") Signed-off-by: Greg Thelen gthelen@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/backing-dev.c | 1 - 1 file changed, 1 deletion(-)
--- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -404,7 +404,6 @@ static void cgwb_release_workfn(struct w blkcg_unpin_online(blkcg);
fprop_local_destroy_percpu(&wb->memcg_completions); - percpu_ref_exit(&wb->refcnt); wb_exit(wb); call_rcu(&wb->rcu, cgwb_free_rcu); }