From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> commit c2e406596571659451f4b95e37ddfd5a8ef1d0dc upstream. Kuyo reports that the pattern of using debugfs_remove(debugfs_lookup()) leaks a dentry and with a hotplug stress test, the machine eventually runs out of memory. Fix this up by using the newly created debugfs_lookup_and_remove() call instead which properly handles the dentry reference counting logic. Cc: Major Chen <major.chen@xxxxxxxxxxx> Cc: stable <stable@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Juri Lelli <juri.lelli@xxxxxxxxxx> Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx> Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Ben Segall <bsegall@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx> Cc: Valentin Schneider <vschneid@xxxxxxxxxx> Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx> Reported-by: Kuyo Chang <kuyo.chang@xxxxxxxxxxxx> Tested-by: Kuyo Chang <kuyo.chang@xxxxxxxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220902123107.109274-2-gregkh@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/sched/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -416,7 +416,7 @@ void update_sched_domain_debugfs(void) char buf[32]; snprintf(buf, sizeof(buf), "cpu%d", cpu); - debugfs_remove(debugfs_lookup(buf, sd_dentry)); + debugfs_lookup_and_remove(buf, sd_dentry); d_cpu = debugfs_create_dir(buf, sd_dentry); i = 0;
