Commit 8fd0e995 authored by Marco Elver's avatar Marco Elver Committed by Linus Torvalds
Browse files

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@google.com


Fixes: 407f1d8c ("kfence: await for allocation using wait_event")
Signed-off-by: default avatarMarco Elver <elver@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Hillf Danton <hdanton@sina.com>
Cc: <stable@vger.kernel.org>	[5.12+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 50c25ee9

mm/kfence/core.c

+3 −3
Original line number Diff line number Diff line
@@ -627,10 +627,10 @@ static void toggle_allocation_gate(struct work_struct *work) 
		 * 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),

		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. */