Re: [PATCH v2] staging: ion: Fix ion_cma_heap allocations

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Dec 13, 2017 at 01:26:04PM -0800, John Stultz wrote:
> In trying to add support for drm_hwcomposer to HiKey,
> I've needed to utilize the ION CMA heap, and I've noticed
> problems with allocations on newer kernels failing.
> 
> It seems back with 204f672255c2 ("ion: Use CMA APIs directly"),
> the ion_cma_heap code was modified to use the CMA API, but
> kept the arguments as buffer lengths rather then number of pages.
> 
> This results in errors as we don't have enough pages in CMA to
> satisfy the exaggerated requests.
> 
> This patch converts the ion_cma_heap CMA API usage to properly
> request pages.
> 
> It also fixes a minor issue in the allocation where in the error
> path, the cma_release is called with the buffer->size value which
> hasn't yet been set.
> 
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> Cc: Archit Taneja <architt@codeaurora.org>
> Cc: Greg KH <gregkh@linuxfoundation.org>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Dmitry Shmidt <dimitrysh@google.com>
> Cc: Todd Kjos <tkjos@google.com>
> Cc: Amit Pundir <amit.pundir@linaro.org>
> Fixes: 204f672255c2 ("staging: android: ion: Use CMA APIs directly")
> Acked-by: Laura Abbott <labbott@redhat.com>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> v2: Fix build errors when CONFIG_CMA_ALIGNMENT isn't defined

Wait, why would CONFIG_CMA_ALIGNMENT not be defined if we are using the
cma code?  Is that a Kconfig issue somehow?

thanks,

greg k-h