Re: [PATCH bpf] bpf/helpers: Skip memcg accounting in __bpf_async_init()

[Peilin Ye <yepeilin@google.com>]

On Fri, Sep 05, 2025 at 12:48:11PM -0700, Shakeel Butt wrote:
> On Fri, Sep 05, 2025 at 10:31:07AM -0700, Shakeel Butt wrote:
> > On Fri, Sep 05, 2025 at 08:18:25AM -0700, Alexei Starovoitov wrote:
> > > On Thu, Sep 4, 2025 at 11:20 PM Peilin Ye <yepeilin@google.com> wrote:
> > > > As pointed out by Kumar, we can use bpf_mem_alloc() and friends for
> > > > bpf_hrtimer and bpf_work, to skip memcg accounting.
> > > 
> > > This is a short term workaround that we shouldn't take.
> > > Long term bpf_mem_alloc() will use kmalloc_nolock() and
> > > memcg accounting that was already made to work from any context
> > > except that the path of memcg_memory_event() wasn't converted.
> > > 
> > > Shakeel,
> > > 
> > > Any suggestions how memcg_memory_event()->cgroup_file_notify()
> > > can be fixed?
> > > Can we just trylock and skip the event?
> > 
> > Will !gfpflags_allow_spinning(gfp_mask) be able to detect such call
> > chains? If yes, then we can change memcg_memory_event() to skip calls to
> > cgroup_file_notify() if spinning is not allowed.
> 
> Along with using __GFP_HIGH instead of GFP_ATOMIC in __bpf_async_init()

Ah, I see, thanks for the suggestion - I'll send a separate patch to do
this.

Peilin Ye