From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> The value of DEFAULT_RCU_BLIMIT is normally set to 10, the idea being to avoid needless response-time degradation due to RCU callback invocation. However, when CONFIG_RCU_STRICT_GRACE_PERIOD=y it is better to avoid throttling callback execution in order to better detect pointer leaks from RCU read-side critical sections. This commit therefore sets the value of DEFAULT_RCU_BLIMIT to 1000 in kernels built with CONFIG_RCU_STRICT_GRACE_PERIOD=y. Reported-by Jann Horn <jannh@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/tree.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index d333f1b..08cc91c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -454,17 +454,18 @@ static int rcu_is_cpu_rrupt_from_idle(void) return __this_cpu_read(rcu_data.dynticks_nesting) == 0; } -#define DEFAULT_RCU_BLIMIT 10 /* Maximum callbacks per rcu_do_batch ... */ -#define DEFAULT_MAX_RCU_BLIMIT 10000 /* ... even during callback flood. */ +#define DEFAULT_RCU_BLIMIT (IS_ENABLED(CONFIG_RCU_STRICT_GRACE_PERIOD) ? 1000 : 10) + // Maximum callbacks per rcu_do_batch ... +#define DEFAULT_MAX_RCU_BLIMIT 10000 // ... even during callback flood. static long blimit = DEFAULT_RCU_BLIMIT; -#define DEFAULT_RCU_QHIMARK 10000 /* If this many pending, ignore blimit. */ +#define DEFAULT_RCU_QHIMARK 10000 // If this many pending, ignore blimit. static long qhimark = DEFAULT_RCU_QHIMARK; -#define DEFAULT_RCU_QLOMARK 100 /* Once only this many pending, use blimit. */ +#define DEFAULT_RCU_QLOMARK 100 // Once only this many pending, use blimit. static long qlowmark = DEFAULT_RCU_QLOMARK; #define DEFAULT_RCU_QOVLD_MULT 2 #define DEFAULT_RCU_QOVLD (DEFAULT_RCU_QOVLD_MULT * DEFAULT_RCU_QHIMARK) -static long qovld = DEFAULT_RCU_QOVLD; /* If this many pending, hammer QS. */ -static long qovld_calc = -1; /* No pre-initialization lock acquisitions! */ +static long qovld = DEFAULT_RCU_QOVLD; // If this many pending, hammer QS. +static long qovld_calc = -1; // No pre-initialization lock acquisitions! module_param(blimit, long, 0444); module_param(qhimark, long, 0444); -- 2.9.5
