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authorMarco Elver <elver@google.com>2021-05-04 18:40:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 11:27:27 -0700
commit37c9284f6932b915043717703d6496dfd59c85f5 (patch)
tree0a37ff3cc6a2b7fcec28e0e8e8b92d28e86c6c5b
parent407f1d8c1b5f3ec66a6a3eb835d3b81c76440f4e (diff)
kfence: maximize allocation wait timeout duration
The allocation wait timeout was initially added because of warnings due to CONFIG_DETECT_HUNG_TASK=y [1]. While the 1 sec timeout is sufficient to resolve the warnings (given the hung task timeout must be 1 sec or larger) it may cause unnecessary wake-ups if the system is idle: https://lkml.kernel.org/r/CADYN=9J0DQhizAGB0-jz4HOBBh+05kMBXb4c0cXMS7Qi5NAJiw@mail.gmail.com Fix it by computing the timeout duration in terms of the current sysctl_hung_task_timeout_secs value. Link: https://lkml.kernel.org/r/20210421105132.3965998-3-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Jann Horn <jannh@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/kfence/core.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 235d726f88bc..9742649f3f88 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -20,6 +20,7 @@
#include <linux/moduleparam.h>
#include <linux/random.h>
#include <linux/rcupdate.h>
+#include <linux/sched/sysctl.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
@@ -621,7 +622,16 @@ static void toggle_allocation_gate(struct work_struct *work)
/* Enable static key, and await allocation to happen. */
static_branch_enable(&kfence_allocation_key);
- wait_event_timeout(allocation_wait, atomic_read(&kfence_allocation_gate), HZ);
+ if (sysctl_hung_task_timeout_secs) {
+ /*
+ * 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);
+ } else {
+ wait_event(allocation_wait, atomic_read(&kfence_allocation_gate));
+ }
/* Disable static key and reset timer. */
static_branch_disable(&kfence_allocation_key);