49 lines
1.6 KiB
Diff
49 lines
1.6 KiB
Diff
From: Peter Zijlstra <peterz@infradead.org>
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Date: Fri, 8 Sep 2023 18:22:48 +0200
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Subject: [PATCH 1/7] sched: Constrain locks in sched_submit_work()
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
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Even though sched_submit_work() is ran from preemptible context,
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it is discouraged to have it use blocking locks due to the recursion
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potential.
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Enforce this.
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Link: https://lkml.kernel.org/r/20230908162254.999499-2-bigeasy@linutronix.de
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---
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kernel/sched/core.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -6721,11 +6721,18 @@ void __noreturn do_task_dead(void)
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static inline void sched_submit_work(struct task_struct *tsk)
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{
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+ static DEFINE_WAIT_OVERRIDE_MAP(sched_map, LD_WAIT_CONFIG);
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unsigned int task_flags;
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if (task_is_running(tsk))
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return;
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+ /*
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+ * Establish LD_WAIT_CONFIG context to ensure none of the code called
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+ * will use a blocking primitive -- which would lead to recursion.
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+ */
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+ lock_map_acquire_try(&sched_map);
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+
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task_flags = tsk->flags;
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/*
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* If a worker goes to sleep, notify and ask workqueue whether it
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@@ -6750,6 +6757,8 @@ static inline void sched_submit_work(str
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* make sure to submit it to avoid deadlocks.
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*/
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blk_flush_plug(tsk->plug, true);
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+
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+ lock_map_release(&sched_map);
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}
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static void sched_update_worker(struct task_struct *tsk)
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