Re: [RFC/PATCH 22/22] RFC: s390/mm: Add gmap lock classes

Janosch Frank
2017-11-15T12:17:01Z

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On 15.11.2017 11:10, David Hildenbrand wrote:
> On 06.11.2017 23:30, Janosch Frank wrote:
>> A shadow gmap and its parent are locked right after each other when
>> doing VSIE management. Lockdep can't differentiate between the two
>> classes without some help.
>>
>> TODO: Not sure yet if I have to annotate all and if gmap_pmd_walk will
>> be used by both shadow and parent
>
> Why is that new, I thought we already had the same situation before and
> lockdep didn't complain?
>
> (worrying of we are now seeing a real problem and try to hide it)

In gmap_protect_rmap we now also need to take the parent's gmap page
table lock, which we didn't need before, because we only touched the
parent's ptes and had pte locks for that.

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