Re: [RFC][PATCH] sched: Fix TASK_DEAD race in finish_task_switch()

From: Linus Torvalds
Date: Tue Sep 29 2015 - 13:42:05 EST

On Tue, Sep 29, 2015 at 12:50 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> The control dependency creates a LOAD->STORE order, that is, no STOREs
> can happen until we observe !p->on_cpu.

Fair enough.

> Right, but wmb isn't sufficient as it doesn't order the prev->state LOAD
> vs the prev->on_cpu = 0 STORE. If those happen in the wrong order the
> described race can happen and we get a use-after-free.

.. and you convinced me. The patch is good. Ack.

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