If once KFENCE is disabled by:
echo 0 > /sys/module/kfence/parameters/sample_interval
KFENCE could never be re-enabled until next rebooting.
Allow re-enabling it by writing a positive num to sample_interval.
Signed-off-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
---
mm/kfence/core.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 13128fa13062..19eb123c0bba 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -55,6 +55,7 @@ EXPORT_SYMBOL_GPL(kfence_sample_interval); /* Export for test modules. */
#endif
#define MODULE_PARAM_PREFIX "kfence."
+static int kfence_enable_late(void);
static int param_set_sample_interval(const char *val, const struct kernel_param *kp)
{
unsigned long num;
@@ -65,10 +66,11 @@ static int param_set_sample_interval(const char *val, const struct kernel_param
if (!num) /* Using 0 to indicate KFENCE is disabled. */
WRITE_ONCE(kfence_enabled, false);
- else if (!READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING)
- return -EINVAL; /* Cannot (re-)enable KFENCE on-the-fly. */
*((unsigned long *)kp->arg) = num;
+
+ if (num && !READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING)
+ return kfence_enable_late();
return 0;
}
@@ -787,6 +789,16 @@ void __init kfence_init(void)
(void *)(__kfence_pool + KFENCE_POOL_SIZE));
}
+static int kfence_enable_late(void)
+{
+ if (!__kfence_pool)
+ return -EINVAL;
+
+ WRITE_ONCE(kfence_enabled, true);
+ queue_delayed_work(system_unbound_wq, &kfence_timer, 0);
+ return 0;
+}
+
void kfence_shutdown_cache(struct kmem_cache *s)
{
unsigned long flags;
--
2.27.0
