Re: [PATCH v2 4/6] mm: replace vma->vm_flags indirect modification in ksm_madvise

Suren Baghdasaryan
2023-01-25T16:57:48Z

On Wed, Jan 25, 2023 at 1:38 AM 'Michal Hocko' via kernel-team
<kernel-team@android.com> wrote:
>
> On Wed 25-01-23 00:38:49, Suren Baghdasaryan wrote:
> > Replace indirect modifications to vma->vm_flags with calls to modifier
> > functions to be able to track flag changes and to keep vma locking
> > correctness. Add a BUG_ON check in ksm_madvise() to catch indirect
> > vm_flags modification attempts.
>
> Those BUG_ONs scream to much IMHO. KSM is an MM internal code so I
> gueess we should be willing to trust it.

Yes, but I really want to prevent an indirect misuse since it was not
easy to find these. If you feel strongly about it I will remove them
or if you have a better suggestion I'm all for it.

>
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
>
> Acked-by: Michal Hocko <mhocko@suse.com>
> --
> Michal Hocko
> SUSE Labs
>
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