Messages in this thread Patch in this message | | | From | Zqiang <> | Subject | [PATCH v3 1/2] rcu-tasks: Stop RCU Tasks scanning no-idle tasks which record on dyntick-idle entry | Date | Tue, 24 May 2022 08:34:53 +0800 |
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When the RCU Tasks scanning on-rq tasks, there is no need to scanning no-idle tasks(have invoked rcu_user_enter()) which record on dyntick-idle entry, at this time, these tasks are not remain within an RCU Tasks read-side critical section.
This commit skip scanning tasks which record on dyntick-idle entry in rcu_tasks_pertask().
Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Zqiang <qiang1.zhang@intel.com> --- kernel/rcu/tasks.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 195c97e85bcb..a28337f280e4 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -809,10 +809,16 @@ static void rcu_tasks_pregp_step(struct list_head *hop) synchronize_rcu(); } +static bool task_is_on_dyntick_idle(struct task_struct *t) +{ + return IS_ENABLED(CONFIG_NO_HZ_FULL) && t->rcu_tasks_idle_cpu >= 0; +} + /* Per-task initial processing. */ static void rcu_tasks_pertask(struct task_struct *t, struct list_head *hop) { - if (t != current && READ_ONCE(t->on_rq) && !is_idle_task(t)) { + if (t != current && READ_ONCE(t->on_rq) && !is_idle_task(t) && + !task_is_on_dyntick_idle(t)) { get_task_struct(t); t->rcu_tasks_nvcsw = READ_ONCE(t->nvcsw); WRITE_ONCE(t->rcu_tasks_holdout, true); @@ -842,8 +848,7 @@ static void check_holdout_task(struct task_struct *t, if (!READ_ONCE(t->rcu_tasks_holdout) || t->rcu_tasks_nvcsw != READ_ONCE(t->nvcsw) || !READ_ONCE(t->on_rq) || - (IS_ENABLED(CONFIG_NO_HZ_FULL) && - !is_idle_task(t) && t->rcu_tasks_idle_cpu >= 0)) { + task_is_on_dyntick_idle(t)) { WRITE_ONCE(t->rcu_tasks_holdout, false); list_del_init(&t->rcu_tasks_holdout_list); put_task_struct(t); -- 2.25.1
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