Messages in this thread Patch in this message | | | From | Sebastian Andrzej Siewior <> | Subject | [PATCH 2/2] genirq: Move prio assignment into the newly created thread | Date | Tue, 10 Nov 2020 12:38:48 +0100 |
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From: Thomas Gleixner <tglx@linutronix.de>
With enabled threaded interrupts the nouveau driver reported the following: | Chain exists of: | &mm->mmap_lock#2 --> &device->mutex --> &cpuset_rwsem | | Possible unsafe locking scenario: | | CPU0 CPU1 | ---- ---- | lock(&cpuset_rwsem); | lock(&device->mutex); | lock(&cpuset_rwsem); | lock(&mm->mmap_lock#2);
The device->mutex is nvkm_device::mutex.
Unblocking the lockchain at `cpuset_rwsem' is probably the easiest thing to do. Move the priority assignment to the start of the newly created thread.
Fixes: 710da3c8ea7df ("sched/core: Prevent race condition between cpuset and __sched_setscheduler()") Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bigeasy: Patch description] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lkml.kernel.org/r/a23a826af7c108ea5651e73b8fbae5e653f16e86.camel@gmx.de --- kernel/irq/manage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index c460e0496006e..079688d122a70 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1155,6 +1155,8 @@ static int irq_thread(void *data) irqreturn_t (*handler_fn)(struct irq_desc *desc, struct irqaction *action); + sched_set_fifo(current); + if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD, &action->thread_flags)) handler_fn = irq_forced_thread_fn; @@ -1320,8 +1322,6 @@ setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary) if (IS_ERR(t)) return PTR_ERR(t); - sched_set_fifo(t); - /* * We keep the reference to the task struct even if * the thread dies to avoid that the interrupt code -- 2.29.2
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