----- On Jul 31, 2017, at 12:13 PM, Paul E. McKenney paulmck@xxxxxxxxxxxxxxxxxx wrote:
> On Mon, Jul 31, 2017 at 01:50:29PM +1000, Stephen Rothwell wrote:
>> Hi Paul,
>>
>> Today's linux-next merge of the rcu tree got a conflict in:
>>
>> arch/x86/mm/tlb.c
>>
>> between commit:
>>
>> 94b1b03b519b ("x86/mm: Rework lazy TLB mode and TLB freshness tracking")
>>
>> from the tip tree and commit:
>>
>> d7713e8f8b23 ("membarrier: Expedited private command")
>>
>> from the rcu tree.
>>
>> I fixed it up (the former removed the comment and the load_cr3(), so I
>> just dropped the commend change in the latter) and can carry the fix as
>> necessary. This is now fixed as far as linux-next is concerned, but any
>> non trivial conflicts should be mentioned to your upstream maintainer
>> when your tree is submitted for merging. You may also want to consider
>> cooperating with the maintainer of the conflicting tree to minimise any
>> particularly complex conflicts.
>
> Thank you, Stephen!
>
> Mathieu, Peter, our commit log reads as if removal of load_cr3() would
> simply result in relying on the ordering provided by the atomic ops
> in switch_mm() for mm_cpumask(), so that only the commit log and the
> comment need changing.
>
> Please let me know if I am missing something here.
I think you are right. Both load_cr3() and mm_cpumask update operations
(LOCK prefixed) provide the appropriate barriers on x86. So it's just a
matter of adapting the comment to the new reality.
Thanks,
Mathieu
>
> Thanx, Paul
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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