5.15-stable review patch. If anyone has any objections, please let me know.
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From: Zijun Hu quic_zijuhu@quicinc.com
commit d1248436cbef1f924c04255367ff4845ccd9025e upstream.
blkcg_fill_root_iostats() iterates over @block_class's devices by class_dev_iter_(init|next)(), but does not end iterating with class_dev_iter_exit(), so causes the class's subsystem refcount leakage.
Fix by ending the iterating with class_dev_iter_exit().
Fixes: ef45fe470e1e ("blk-cgroup: show global disk stats in root cgroup io.stat") Reviewed-by: Michal Koutný mkoutny@suse.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Acked-by: Tejun Heo tj@kernel.org Signed-off-by: Zijun Hu quic_zijuhu@quicinc.com Link: https://lore.kernel.org/r/20250105-class_fix-v6-2-3a2f1768d4d4@quicinc.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-cgroup.c | 1 + 1 file changed, 1 insertion(+)
--- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -894,6 +894,7 @@ static void blkcg_fill_root_iostats(void blkg_iostat_set(&blkg->iostat.cur, &tmp); u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); } + class_dev_iter_exit(&iter); }
static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s)