From: Andrew Morton <akpm@linux-foundation.org>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
Peilin Ye <yepeilin@google.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org,
Meta kernel team <kernel-team@meta.com>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v2] memcg: skip cgroup_file_notify if spinning is not allowed
Date: Mon, 22 Sep 2025 16:43:28 -0700 [thread overview]
Message-ID: <20250922164328.0d766c95f9c15330e99514bd@linux-foundation.org> (raw)
In-Reply-To: <nzr2ztya3duztwfnpcnl2azzcdg74hjbwzzs3nxax67nsu6ffq@leycq6l5d5y2>
On Mon, 22 Sep 2025 16:22:57 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> >
> > > --- a/mm/memcontrol.c
> > > +++ b/mm/memcontrol.c
> > > @@ -2307,12 +2307,13 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
> > > bool drained = false;
> > > bool raised_max_event = false;
> > > unsigned long pflags;
> > > + bool allow_spinning = gfpflags_allow_spinning(gfp_mask);
> > >
> >
> > Does this affect only the problematic call chain which you have
> > identified, or might other callers be undesirably affected?
>
> It will only affect the call chain which can not spin due to possibly
> NMI context and at the moment only bpf programs can cause that.
"possibly" NMI context? Is it possible that a bpf caller which could
have taken locks will now skip the notifications? Or do the gfp_flags
get propagated all the way through?
next prev parent reply other threads:[~2025-09-22 23:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-22 22:02 Shakeel Butt
2025-09-22 23:03 ` Andrew Morton
2025-09-22 23:22 ` Shakeel Butt
2025-09-22 23:43 ` Andrew Morton [this message]
2025-09-22 23:57 ` Shakeel Butt
2025-09-22 23:04 ` Andrew Morton
2025-09-22 23:39 ` Shakeel Butt
2025-09-22 23:55 ` Andrew Morton
2025-09-23 0:00 ` Shakeel Butt
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