Re: [PATCH] dma-buf: system_heap: do not warn for costly allocation

[Minchan Kim <minchan@kernel.org>]

On Wed, Feb 10, 2021 at 09:24:52AM -0800, Suren Baghdasaryan wrote:
> The code looks fine to me. Description needs a bit polishing :)
> 
> On Wed, Feb 10, 2021 at 8:26 AM Minchan Kim <minchan@kernel.org> wrote:
> >
> > Linux VM is not hard to support PAGE_ALLOC_COSTLY_ODER allocation
> > so normally expects driver passes __GFP_NOWARN in that case
> > if they has fallback options.
> >
> > system_heap in dmabuf is the case so do not flood into demsg
> > with the warning for recording more precious information logs.
> > (below is ION warning example I got but dmabuf system heap is
> > nothing different).
> 
> Suggestion:
> Dmabuf system_heap allocation logic starts with the highest necessary
> allocation order before falling back to lower orders. The requested
> order can be higher than PAGE_ALLOC_COSTLY_ODER and failures to
> allocate will flood dmesg with warnings. Such high-order allocations
> are not unexpected and are handled by the system_heap's allocation
> fallback mechanism.
> Prevent these warnings when allocating higher than
> PAGE_ALLOC_COSTLY_ODER pages using __GFP_NOWARN flag.
> 
> Below is ION warning example I got but dmabuf system heap is nothing different:

I will take it.
Thanks, Suren!