Re: [RFC PATCH 2/3] sched: membarrier: cover kthread_use_mm (v2)

[Mathieu Desnoyers]

----- On Aug 16, 2020, at 3:09 AM, Hillf Danton hdanton@xxxxxxxx wrote:

> On Fri, 14 Aug 2020 12:43:57 -0400 Mathieu Desnoyers wrote:
>> 
>> Given that no prior kthread use this guarantee and that it only affects
>> kthreads, adding this guarantee does not affect user-space ABI.
> 
> Can you expand a bit on why kthreads like ksoftirqd have to ack the
> IPIs from Dave who's not CAP_SYS_ADMIN.

Do ksoftirqd kthreads ever use kthread_use_mm() to access user
processes' memory ? If not, then they won't be disturbed by any IPI.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com