From: Marco Elver <elver@xxxxxxxxxx> Subject: kfence: use TASK_IDLE when awaiting allocation Since wait_event() uses TASK_UNINTERRUPTIBLE by default, waiting for an allocation counts towards load. However, for KFENCE, this does not make any sense, since there is no busy work we're awaiting. Instead, use TASK_IDLE via wait_event_idle() to not count towards load. BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1185565 Link: https://lkml.kernel.org/r/20210521083209.3740269-1-elver@xxxxxxxxxx Fixes: 407f1d8c1b5f ("kfence: await for allocation using wait_event") Signed-off-by: Marco Elver <elver@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Cc: Hillf Danton <hdanton@xxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [5.12+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/kfence/core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/mm/kfence/core.c~kfence-use-task_idle-when-awaiting-allocation +++ a/mm/kfence/core.c @@ -627,10 +627,10 @@ static void toggle_allocation_gate(struc * During low activity with no allocations we might wait a * while; let's avoid the hung task warning. */ - wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), - sysctl_hung_task_timeout_secs * HZ / 2); + wait_event_idle_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), + sysctl_hung_task_timeout_secs * HZ / 2); } else { - wait_event(allocation_wait, atomic_read(&kfence_allocation_gate)); + wait_event_idle(allocation_wait, atomic_read(&kfence_allocation_gate)); } /* Disable static key and reset timer. */ _
