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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Quentin Monnet <quentin@isovalent.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hao Luo <haoluo@google.com>, bpf <bpf@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH bpf-next v2 1/2] bpf: Make non-preallocated allocation low priority
Date: Thu, 7 Jul 2022 08:44:37 -0700	[thread overview]
Message-ID: <CAADnVQKJ44nmxzUDAkckXJ2mzJAshvzzGFP-oPT=NO3rGW7pQA@mail.gmail.com> (raw)
In-Reply-To: <CALOAHbC4RG_G2wjU0Nj_A9MhrHiQ7GXR7Yp7BCr+7dDmXwR-4w@mail.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?

  reply	other threads:[~2022-07-07 15:44 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-06 15:58 [PATCH bpf-next v2 0/2] bpf: Minor fixes for non-preallocated memory Yafang Shao
2022-07-06 15:58 ` [PATCH bpf-next v2 1/2] bpf: Make non-preallocated allocation low priority Yafang Shao
2022-07-06 16:47   ` Alexei Starovoitov
2022-07-06 19:09     ` Roman Gushchin
2022-07-06 22:11       ` Alexei Starovoitov
2022-07-06 22:54         ` Roman Gushchin
2022-07-06 23:22           ` Alexei Starovoitov
2022-07-07  0:07   ` Shakeel Butt
2022-07-07  0:14     ` Alexei Starovoitov
2022-07-07  0:25     ` Roman Gushchin
2022-07-07  2:09       ` Alexei Starovoitov
2022-07-07  3:36         ` Roman Gushchin
2022-07-07 10:27     ` Yafang Shao
2022-07-07 15:44       ` Alexei Starovoitov [this message]
2022-07-07 16:19         ` Yafang Shao
2022-07-06 15:58 ` [PATCH bpf-next v2 2/2] bpf: Warn on non-preallocated case for missed trace types Yafang Shao
2022-07-06 16:50   ` Alexei Starovoitov
2022-07-07 10:29     ` Yafang Shao
2022-07-07 15:45       ` Alexei Starovoitov
2022-07-07 16:22         ` Yafang Shao

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