6.12-stable review patch. If anyone has any objections, please let me know.
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From: Chuyi Zhou zhouchuyi@bytedance.com
[ 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 --- kernel/sched/ext.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 45e7461fd4c94..b88fa640325e5 100644 --- 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); }