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SubjectRe: [PATCH v2 14/20] mm: Provide speculative fault infrastructure
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On 29/08/2017 14:04, Peter Zijlstra wrote:
> On Tue, Aug 29, 2017 at 09:59:30AM +0200, Laurent Dufour wrote:
>> On 27/08/2017 02:18, Kirill A. Shutemov wrote:
>>>> +
>>>> + if (unlikely(!vma->anon_vma))
>>>> + goto unlock;
>>>
>>> It deserves a comment.
>>
>> You're right I'll add it in the next version.
>> For the record, the root cause is that __anon_vma_prepare() requires the
>> mmap_sem to be held because vm_next and vm_prev must be safe.
>
> But should that test not be:
>
> if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma))
> goto unlock;
>
> Because !anon vmas will never have ->anon_vma set and you don't want to
> exclude those.

Yes in the case we later allow non anonymous vmas to be handled.
Currently only anonymous vmas are supported so the check is good enough,
isn't it ?

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