Re: [PATCH bpf-next v2 1/2] bpf: Make non-preallocated allocation low priority

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

On Thu, Jul 7, 2022 at 3:28 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> On Thu, Jul 7, 2022 at 8:07 AM Shakeel Butt <shakeelb@google.com> wrote:
> >
> > On Wed, Jul 06, 2022 at 03:58:47PM +0000, Yafang Shao wrote:
> > > GFP_ATOMIC doesn't cooperate well with memcg pressure so far, especially
> > > if we allocate too much GFP_ATOMIC memory. For example, when we set the
> > > memcg limit to limit a non-preallocated bpf memory, the GFP_ATOMIC can
> > > easily break the memcg limit by force charge. So it is very dangerous to
> > > use GFP_ATOMIC in non-preallocated case. One way to make it safe is to
> > > remove __GFP_HIGH from GFP_ATOMIC, IOW, use (__GFP_ATOMIC |
> > > __GFP_KSWAPD_RECLAIM) instead, then it will be limited if we allocate
> > > too much memory.
> >
> > Please use GFP_NOWAIT instead of (__GFP_ATOMIC | __GFP_KSWAPD_RECLAIM).
> > There is already a plan to completely remove __GFP_ATOMIC and mm-tree
> > already have a patch for that.
> >
>
> After reading the discussion[1], it looks good to me to use GFP_NOWAIT
> instead. I will update it.

Should we use GFP_ATOMIC | __GFP_NOMEMALLOC instead
to align with its usage in the networking stack?