v2: - Remove unnecessary rcu_read_{lock|unlock} from cgroup_rstat_css_cpu_flush() in patch 3. It was found that blkcg_destroy_blkgs() may be called with all blkcg references gone. This may potentially cause user-after-free and so should be fixed. The last 2 patches are miscellaneous cleanups of commit 3b8cc6298724 ("blk-cgroup: Optimize blkcg_rstat_flush()"). Waiman Long (3): bdi, blk-cgroup: Fix potential UAF of blkcg blk-cgroup: Don't flush a blkg if destroyed blk-cgroup: Flush stats at blkgs destruction path block/blk-cgroup.c | 26 ++++++++++++++++++++++++++ include/linux/cgroup.h | 1 + kernel/cgroup/rstat.c | 18 ++++++++++++++++++ mm/backing-dev.c | 8 ++++++-- 4 files changed, 51 insertions(+), 2 deletions(-) -- 2.31.1