Re: [PATCH 2/2] io_uring: use TWA_SIGNAL for task_work if the task isn't running

On 08/11, Oleg Nesterov wrote:

On 08/11, Peter Zijlstra wrote:

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On Tue, Aug 11, 2020 at 08:45:16AM +0200, Oleg Nesterov wrote:

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->jobctl is always modified with ->siglock held, do we really need WRITE_ONCE() ?

In theory, yes. The compiler doesn't know about locks, it can tear writes whenever it feels like it.

Yes, but why does this matter? Could you spell please?

Do you mean that compiler can temporary set/clear JOBCTL_TASK_WORK when it sets/clears another bit?

Oleg.