The patch titled Subject: kfence: use TASK_IDLE when awaiting allocation has been added to the -mm tree. Its filename is kfence-use-task_idle-when-awaiting-allocation.patch

This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/kfence-use-task_idle-when-awaiting... and later at https://ozlabs.org/~akpm/mmotm/broken-out/kfence-use-task_idle-when-awaiting...

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------------------------------------------------------ From: Marco Elver elver@google.com 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@google.com Fixes: 407f1d8c1b5f ("kfence: await for allocation using wait_event") Signed-off-by: Marco 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: Andrew Morton akpm@linux-foundation.org ---

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. */ _

Patches currently in -mm which might be from elver@google.com are

kfence-use-task_idle-when-awaiting-allocation.patch mm-slub-change-run-time-assertion-in-kmalloc_index-to-compile-time-fix.patch printk-introduce-dump_stack_lvl-fix.patch kfence-unconditionally-use-unbound-work-queue.patch