Re: + c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm- num_exe_file_vmas-removal.patch added to -mm tree

[Oleg Nesterov <oleg@redhat.com>]

On 04/20, Cyrill Gorcunov wrote:
>
> Guys, while I more-less agree with Matt about single-shot behaviour
>
> [ let me copy my and his email
>
>   >> With mm->exe_file this prctl option become a one-shot
>   >> only, and while at moment our user-space tool can perfectly
>   >> live with that I thought that there is no strict need to
>   >> limit the option this way from the very beginning.
>   >>
>   > As far as backward compatibility, isn't it better to lift that restriction
>   > later rather than add it? I think the latter would very likely "break"
>   > things whereas the former would not.
>   >
>   > I also prefer that restriction because it establishes a bound on how
>   > frequently the symlink can change. Keeping it a one-shot deal makes the
>   > values that show up in tools like top more reliable for admins.
> ]
>
> I guess maybe it's time to drop one-shot requirement and as result
> we can drop MMF_EXE_FILE_CHANGED bit completely,

Plus perhaps we can remove this for_each_vma check?

> making overall code
> simplier?

Personally I'd certainly prefer this ;)



But let me repeat to avoid the confusion. I am fine either way,
I am not going to discuss this again unless I see something which
looks technically wrong. And the current MMF_EXE_FILE_CHANGED
doesn't look right even if the problem is minor.

Oleg.