Re: [PATCH v2 3/6] mm: replace vma->vm_flags direct modifications with modifier calls

Suren Baghdasaryan
2023-01-25T16:55:12Z

On Wed, Jan 25, 2023 at 1:30 AM 'Michal Hocko' via kernel-team
<kernel-team@android.com> wrote:
>
> On Wed 25-01-23 00:38:48, Suren Baghdasaryan wrote:
> > Replace direct modifications to vma->vm_flags with calls to modifier
> > functions to be able to track flag changes and to keep vma locking
> > correctness.
>
> Is this a manual (git grep) based work or have you used Coccinele for
> the patch generation?

It was a manual "search and replace" and in the process I temporarily
renamed vm_flags to ensure I did not miss any usage.

>
> My potentially incomplete check
> $ git grep ">[[:space:]]*vm_flags[[:space:]]*[&|^]="
>
> shows that nothing should be left after this. There is still quite a lot
> of direct checks of the flags (more than 600). Maybe it would be good to
> make flags accessible only via accessors which would also prevent any
> future direct setting of those flags in uncontrolled way as well.

Yes, I think Peter's suggestion in the first patch would also require
that. Much more churn but probably worth it for the future
maintenance. I'll add a patch which converts all readers as well.

>
> Anyway
> Acked-by: Michal Hocko <mhocko@suse.com>

Thanks for all the reviews!

> --
> Michal Hocko
> SUSE Labs
>
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