The following commit has been merged into the locking/core branch of tip:
Commit-ID: 28bc55f654de49f6122c7475b01b5d5ef4bdf0d4
Gitweb: https://git.kernel.org/tip/28bc55f654de49f6122c7475b01b5d5ef4bdf0d4
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 08 Sep 2023 18:22:48 +02:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 20 Sep 2023 09:31:11 +02:00
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@xxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20230908162254.999499-2-bigeasy@xxxxxxxxxxxxx
---
kernel/sched/core.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2299a5c..d555640 100644
--- 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)
|