Re: [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm

[Christoph Hellwig]

On Wed, May 17, 2023 at 01:22:51PM +0530, Sumit Garg wrote:
> > > +#if IS_ENABLED(CONFIG_CMA)
> > > +     page_flag |= FOLL_LONGTERM;
> > > +#endif
> > >       if (flags & TEE_SHM_USER_MAPPED)
> >
> > If this mapping is long live it should always use FOLL_LONGTERM.
> 
> It depends on the userspace application needs. However, I think it
> should be safe to use FOLL_LONGTERM by default to serve cases like
> secure media playback.

long term is defined as won't automatically go away during the same
syscall.