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

[Xiaoming Ding (丁晓明)]

On Wed, 2023-05-17 at 01:08 -0700, Christoph Hellwig wrote:
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> 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.

thanks for the suggestion.
I will update the patch with using FOLL_LONGTERM by default.