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SubjectRe: [PATCH v3 1/7] kernel/fork: convert vma assignment to a memcpy
On Wed, 25 Jan 2023 16:50:01 -0800 Suren Baghdasaryan <surenb@google.com> wrote:

> On Wed, Jan 25, 2023 at 4:22 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > On Wed, 25 Jan 2023 15:35:48 -0800 Suren Baghdasaryan <surenb@google.com> wrote:
> >
> > > Convert vma assignment in vm_area_dup() to a memcpy() to prevent compiler
> > > errors when we add a const modifier to vma->vm_flags.
> > >
> > > ...
> > >
> > > --- a/kernel/fork.c
> > > +++ b/kernel/fork.c
> > > @@ -482,7 +482,7 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
> > > * orig->shared.rb may be modified concurrently, but the clone
> > > * will be reinitialized.
> > > */
> > > - *new = data_race(*orig);
> > > + memcpy(new, orig, sizeof(*new));
> >
> > The data_race() removal is unchangelogged?
>
> True. I'll add a note in the changelog about that. Ideally I would
> like to preserve it but I could not find a way to do that.
>

Perhaps Paul can comment?

I wonder if KCSAN knows how to detect this race, given that it's now in
a memcpy. I assume so.

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