sched: Constrain locks in sched_submit_work()

Even though sched_submit_work() is ran from preemptible context,
it is discouraged to have it use blocking locks due to the recursion
potential.

Enforce this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-2-bigeasy@linutronix.de

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2299a5cfbfb9ed250695edb75d977edbe61eaf43..d55564097bd860998ff66b1cceca66fce0b0969c 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6720,11 +6720,18 @@ void __noreturn do_task_dead(void)
 
 static inline void sched_submit_work(struct task_struct *tsk)
 {
+       static DEFINE_WAIT_OVERRIDE_MAP(sched_map, LD_WAIT_CONFIG);
        unsigned int task_flags;
 
        if (task_is_running(tsk))
                return;
 
+       /*
+        * Establish LD_WAIT_CONFIG context to ensure none of the code called
+        * will use a blocking primitive -- which would lead to recursion.
+        */
+       lock_map_acquire_try(&sched_map);
+
        task_flags = tsk->flags;
        /*
         * If a worker goes to sleep, notify and ask workqueue whether it
@@ -6749,6 +6756,8 @@ static inline void sched_submit_work(struct task_struct *tsk)
         * make sure to submit it to avoid deadlocks.
         */
        blk_flush_plug(tsk->plug, true);
+
+       lock_map_release(&sched_map);
 }
 
 static void sched_update_worker(struct task_struct *tsk)