sched_ext: Use SCX_CALL_OP_TASK in task_tick_scx

[ Upstream commit f5717c93a1b999970f3a64d771a1a9ee68cc37d0 ]

Now when we use scx_bpf_task_cgroup() in ops.tick() to get the cgroup of
the current task, the following error will occur:

scx_foo[3795244] triggered exit kind 1024:
  runtime error (called on a task not being operated on)

The reason is that we are using SCX_CALL_OP() instead of SCX_CALL_OP_TASK()
when calling ops.tick(), which triggers the error during the subsequent
scx_kf_allowed_on_arg_tasks() check.

SCX_CALL_OP_TASK() was first introduced in commit 36454023f50b ("sched_ext:
Track tasks that are subjects of the in-flight SCX operation") to ensure
task's rq lock is held when accessing task's sched_group. Since ops.tick()
is marked as SCX_KF_TERMINAL and task_tick_scx() is protected by the rq
lock, we can use SCX_CALL_OP_TASK() to avoid the above issue. Similarly,
the same changes should be made for ops.disable() and ops.exit_task(), as
they are also protected by task_rq_lock() and it's safe to access the
task's task_group.

Fixes: 36454023f50b ("sched_ext: Track tasks that are subjects of the in-flight SCX operation")
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 45e7461fd4c945ea4d59524ba74697c82833d84a..b88fa640325e5aad090dda9005c41537b90bcc44 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -3447,7 +3447,7 @@ static void task_tick_scx(struct rq *rq, struct task_struct *curr, int queued)
                curr->scx.slice = 0;
                touch_core_sched(rq, curr);
        } else if (SCX_HAS_OP(tick)) {
-               SCX_CALL_OP(SCX_KF_REST, tick, curr);
+               SCX_CALL_OP_TASK(SCX_KF_REST, tick, curr);
        }
 
        if (!curr->scx.slice)
@@ -3594,7 +3594,7 @@ static void scx_ops_disable_task(struct task_struct *p)
        WARN_ON_ONCE(scx_get_task_state(p) != SCX_TASK_ENABLED);
 
        if (SCX_HAS_OP(disable))
-               SCX_CALL_OP(SCX_KF_REST, disable, p);
+               SCX_CALL_OP_TASK(SCX_KF_REST, disable, p);
        scx_set_task_state(p, SCX_TASK_READY);
 }
 
@@ -3623,7 +3623,7 @@ static void scx_ops_exit_task(struct task_struct *p)
        }
 
        if (SCX_HAS_OP(exit_task))
-               SCX_CALL_OP(SCX_KF_REST, exit_task, p, &args);
+               SCX_CALL_OP_TASK(SCX_KF_REST, exit_task, p, &args);
        scx_set_task_state(p, SCX_TASK_NONE);
 }