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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Lorenz Bauer <lmb@cloudflare.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	kernel-team <kernel-team@cloudflare.com>,
	bpf <bpf@vger.kernel.org>,
	regressions@lists.linux.dev, Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: Verifier rejects previously accepted program
Date: Fri, 5 Nov 2021 12:49:52 -0700	[thread overview]
Message-ID: <20211105194952.xve6u6lgh2oy46dy@ast-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <CACAyw9_GmNotSyG0g1OOt648y9kx5Bd72f58TtS-QQD9FaV06w@mail.gmail.com>

On Fri, Nov 05, 2021 at 10:41:40AM +0000, Lorenz Bauer wrote:
> 
> bpf-next with f30d4968e9ae on top:
> 
>     works!

Awesome.

> commit 3e8ce29850f1 ("bpf: Prevent pointer mismatch in
> bpf_timer_init.") (found via bisection):
> 
>     BPF program is too large. Processed 1000001 insn
> 
> commit 3e8ce29850f1^ ("bpf: Add map side support for bpf timers."):
> 
>    works!

So with just 3e8ce29850f1 it's "too large" and with parent commit it works ?
I've analyzed offending commit again and don't see how it can be causing
state pruning to be more conservative for your asm.
reg->map_uid should only be non-zero for lookups from inner maps,
but your asm doesn't have lookups at all in that loop.
Maybe in some case map_uid doesn't get cleared, but I couldn't find
such code path with manual code analysis.
I think it's worth investigating further.
Please craft a reproducer.

  reply	other threads:[~2021-11-05 19:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-03 11:55 Verifier rejects previously accepted program Lorenz Bauer
2021-11-04 16:50 ` Alexei Starovoitov
2021-11-04 23:30   ` sdf
2021-11-05  1:20     ` Alexei Starovoitov
2021-11-05  4:13       ` Stanislav Fomichev
2021-11-05 10:41   ` Lorenz Bauer
2021-11-05 19:49     ` Alexei Starovoitov [this message]
2021-11-08 13:21       ` Lorenz Bauer
2021-11-10  4:25         ` Alexei Starovoitov
2021-11-10 11:41           ` Lorenz Bauer
2021-11-10 16:50             ` Alexei Starovoitov
2021-11-10 17:05               ` Lorenz Bauer
2021-11-10 18:01               ` Thorsten Leemhuis
2021-11-10 19:16                 ` Alexei Starovoitov
2021-11-10 19:49                   ` Thorsten Leemhuis
2021-11-16  9:26 ` Lorenz Bauer
2021-11-16 10:59   ` Thorsten Leemhuis

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