Messages in this thread Patch in this message | | | Date | Tue, 15 Aug 2023 13:01:22 +0200 | From | Peter Zijlstra <> | Subject | [PATCH 1/6] sched: Constrain locks in sched_submit_work() |
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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> --- kernel/sched/core.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6737,11 +6737,18 @@ 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 @@ -6766,6 +6773,8 @@ static inline void sched_submit_work(str * 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)
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