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From: KP Singh <kpsingh@kernel.org>
To: Alexei Starovoitov <ast@fb.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>, bpf <bpf@vger.kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v3 bpf-next 7/8] bpf: Allows per-cpu maps and map-in-map in sleepable programs
Date: Wed, 10 Feb 2021 00:22:20 +0100	[thread overview]
Message-ID: <CACYkzJ6Cda4QR8m8QJ_SZ0rx0hj3LQahrz4cwiNuPC9PVRhyFQ@mail.gmail.com> (raw)
In-Reply-To: <61dffef3-ab23-8d9b-70da-3e84caa84fe3@fb.com>

On Wed, Feb 10, 2021 at 12:14 AM Alexei Starovoitov <ast@fb.com> wrote:
>
> On 2/9/21 2:43 PM, KP Singh wrote:
> > On Tue, Feb 9, 2021 at 11:32 PM Alexei Starovoitov <ast@fb.com> wrote:
> >>
> >> On 2/9/21 1:12 PM, KP Singh wrote:
> >>> On Tue, Feb 9, 2021 at 9:57 PM Alexei Starovoitov
> >>> <alexei.starovoitov@gmail.com> wrote:
> >>>>
> >>>> From: Alexei Starovoitov <ast@kernel.org>
> >>>>
> >>>> Since sleepable programs are now executing under migrate_disable
> >>>> the per-cpu maps are safe to use.
> >>>> The map-in-map were ok to use in sleepable from the time sleepable
> >>>> progs were introduced.
> >>>>
> >>>> Note that non-preallocated maps are still not safe, since there is
> >>>> no rcu_read_lock yet in sleepable programs and dynamically allocated
> >>>> map elements are relying on rcu protection. The sleepable programs
> >>>> have rcu_read_lock_trace instead. That limitation will be addresses
> >>>> in the future.
> >>>>
> >>>> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> >>>> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> >>>
> >>> Acked-by: KP Singh <kpsingh@kernel.org>
> >>>
> >>> Thanks! I actually tested out some of our logic which uses per-cpu maps by
> >>> switching the programs to their sleepable counterparts
> >>
> >> You mean after applying this set, right?
> >> migrate_disable is the key.
> >> It will be difficult to backport to your kernels though.
> >> The bpf change to enable per-cpu is easy, but backporting
> >> sched support is a different game.
> >>
> >
> > Yes after applying the whole set.
> >
> > Also, I think I also got it to work on 5.10 by (I am little less sure
> > of this one though)
> >
> > -  Backporting https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=12fa97c64dce2f3c2e6eed5dc618bb9046e40bf0
> > -  Backporting https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=74d862b682f51e45d25b95b1ecf212428a4967b0
> > - And, backporting this set (I initially missed
> > https://lore.kernel.org/bpf/20210209194856.24269-3-alexei.starovoitov@gmail.com
> > where you add the
> >    calls and ran into issues).
>
> and the whole machinery that it depends on.

 https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=12fa97c64dce2f3c2e6eed5dc618bb9046e40bf0
and https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=74d862b682f51e45d25b95b1ecf212428a4967b0
is the machinery I could find between 5.10 and now. But the backport
is not really relevant here, I just mentioned it to clarify that I was
testing the series more than just applying this single patch :)

  reply	other threads:[~2021-02-09 23:47 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-09 19:48 [PATCH v3 bpf-next 0/8] bpf: Misc improvements Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 1/8] bpf: Optimize program stats Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 2/8] bpf: Compute program stats for sleepable programs Alexei Starovoitov
2021-02-09 22:47   ` KP Singh
2021-02-09 23:11     ` Alexei Starovoitov
2021-02-09 23:17       ` KP Singh
2021-02-09 19:48 ` [PATCH v3 bpf-next 3/8] bpf: Add per-program recursion prevention mechanism Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 4/8] selftest/bpf: Add a recursion test Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 5/8] bpf: Count the number of times recursion was prevented Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 6/8] selftests/bpf: Improve recursion selftest Alexei Starovoitov
2021-02-09 19:48 ` [PATCH v3 bpf-next 7/8] bpf: Allows per-cpu maps and map-in-map in sleepable programs Alexei Starovoitov
2021-02-09 21:12   ` KP Singh
2021-02-09 22:31     ` Alexei Starovoitov
2021-02-09 22:43       ` KP Singh
2021-02-09 23:13         ` Alexei Starovoitov
2021-02-09 23:22           ` KP Singh [this message]
2021-02-09 19:48 ` [PATCH v3 bpf-next 8/8] selftests/bpf: Add a test for map-in-map and per-cpu maps in sleepable progs Alexei Starovoitov
2021-02-09 21:14   ` KP Singh

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