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Subject: Re: [PATCH v5.5 10/10] mmap locking API: rename mmap_sem to mmap_lock
To:     Michel Lespinasse <walken@google.com>
CC:     Matthew Wilcox <willy@infradead.org>,
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From:   John Hubbard <jhubbard@nvidia.com>
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On 2020-05-19 19:39, Michel Lespinasse wrote:
...
>> That gives you additional options inside internal_get_user_pages_fast(), such
>> as, approximately:
>>
>> if (!(gup_flags & FOLL_FAST_ONLY))
>>          might_lock_read(&current->mm->mmap_lock);
>>
>> ...not that that is necessarily a great idea, seeing as how it merely changes
>> "might lock" into "maybe might lock".  :)
> 
> I think that is completely fine, makes sure everyone not using
> FOLL_FAST_ONLY realizes that the call could block.
> 
> Can I ask you to add that assertion in your patchset ? Based on
> Matthew's feedback, I would do it in my patchset, but it doesn't seem
> worth doing if we know this will conflict with your changes.
> 

Sure, that's no problem. Although it looks like my changes may land
in mmotm first, and then your patchset, so maybe the right move is to
make this change *after* both of those things happen, yes?


thanks,
-- 
John Hubbard
NVIDIA