Commit 207d76a3 authored by Tejun Heo's avatar Tejun Heo
Browse files

sched_ext: Pass held rq to SCX_CALL_OP() for dump_cpu/dump_task 



scx_dump_state() walks CPUs with rq_lock_irqsave() held and invokes
ops.dump_cpu / ops.dump_task with NULL locked_rq, leaving
scx_locked_rq_state NULL. If the BPF callback calls a kfunc that
re-acquires rq based on scx_locked_rq() - e.g. scx_bpf_cpuperf_set(cpu)
- it re-acquires the already-held rq.

Pass the held rq to SCX_CALL_OP(). Thread it into scx_dump_task() too.
The pre-loop ops.dump call runs before rq_lock_irqsave() so keeps
rq=NULL.

Fixes: 07814a94 ("sched_ext: Print debug dump after an error exit")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: default avatarChris Mason <clm@meta.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarAndrea Righi <arighi@nvidia.com>
parent 7fb39e4e

kernel/sched/ext.c

+6 −8
Original line number Diff line number Diff line
@@ -6117,9 +6117,8 @@ static void ops_dump_exit(void) 
	scx_dump_data.cpu = -1;

}



static void scx_dump_task(struct scx_sched *sch,

			  struct seq_buf *s, struct scx_dump_ctx *dctx,

			  struct task_struct *p, char marker)

static void scx_dump_task(struct scx_sched *sch, struct seq_buf *s, struct scx_dump_ctx *dctx,

			  struct rq *rq, struct task_struct *p, char marker)

{

	static unsigned long bt[SCX_EXIT_BT_LEN];

	struct scx_sched *task_sch = scx_task_sched(p);
@@ -6160,7 +6159,7 @@ static void scx_dump_task(struct scx_sched *sch, 


	if (SCX_HAS_OP(sch, dump_task)) {

		ops_dump_init(s, "    ");

		SCX_CALL_OP(sch, dump_task, NULL, dctx, p);

		SCX_CALL_OP(sch, dump_task, rq, dctx, p);

		ops_dump_exit();

	}
@@ -6284,8 +6283,7 @@ static void scx_dump_state(struct scx_sched *sch, struct scx_exit_info *ei, 
		used = seq_buf_used(&ns);

		if (SCX_HAS_OP(sch, dump_cpu)) {

			ops_dump_init(&ns, "  ");

			SCX_CALL_OP(sch, dump_cpu, NULL,

				    &dctx, cpu, idle);

			SCX_CALL_OP(sch, dump_cpu, rq, &dctx, cpu, idle);

			ops_dump_exit();

		}
@@ -6308,11 +6306,11 @@ static void scx_dump_state(struct scx_sched *sch, struct scx_exit_info *ei, 


		if (rq->curr->sched_class == &ext_sched_class &&

		    (dump_all_tasks || scx_task_on_sched(sch, rq->curr)))

			scx_dump_task(sch, &s, &dctx, rq->curr, '*');

			scx_dump_task(sch, &s, &dctx, rq, rq->curr, '*');



		list_for_each_entry(p, &rq->scx.runnable_list, scx.runnable_node)

			if (dump_all_tasks || scx_task_on_sched(sch, p))

				scx_dump_task(sch, &s, &dctx, p, ' ');

				scx_dump_task(sch, &s, &dctx, rq, p, ' ');

	next:

		rq_unlock_irqrestore(rq, &rf);

	}