Re: [PATCH v2] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW

[David Hildenbrand]

On 10.08.22 11:12, David Laight wrote:
> From: David Hildenbrand
>> Sent: 09 August 2022 21:57
> ...
> 
> These two functions seem to contain a lot of the same tests.

Yes, but after Linus and I discussed to not even reuse is_cow_mapping()
but instead to spell it out, I refrained from factoring common checks
out here to harm readability.

[...]

> 
> Perhaps only the initial call (common success path?) should
> be inlined?
> With the flags and vma tests being moved to an inline helper.

Do we really care enough to hurt readability? I mean, most things here
are simple bit checks, not expensive function calls.

inline is only a hint to the compiler after all. Please correct me if
I'm wrong.


Now, I don't have any strong opinion, but I do want to make progress for
this because -stable trees still need fixing and I'll be posting the
reproducer on Monday.


Thanks

-- 
Thanks,

David / dhildenb