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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49808690ffbsm185355055e9.10.2026.08.02.14.59.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 02 Aug 2026 14:59:19 -0700 (PDT) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sun, 02 Aug 2026 23:59:19 +0200 Message-Id: Cc: "Andrii Nakryiko" , "Alexei Starovoitov" , "Daniel Borkmann" , "Emil Tsalapatis" , , Subject: Re: [PATCH bpf-next v1 1/3] bpf: Show more useful info in stack depth stats From: "Kumar Kartikeya Dwivedi" To: "Eduard Zingerman" , X-Mailer: aerc 0.21.0 References: <20260801230400.850271-1-memxor@gmail.com> <20260801230400.850271-2-memxor@gmail.com> In-Reply-To: On Sun Aug 2, 2026 at 11:02 PM CEST, Eduard Zingerman wrote: > On Sun, 2026-08-02 at 01:03 +0200, Kumar Kartikeya Dwivedi wrote: >> Currently, the output of stack depth statistics is two crude, with a >> list of captured stack depths ordered by the subprog numbers. The actual >> subprog numbers are determined by libbpf, hence it is hard to associate >> the stack depth statistic back to the subprog by name. >> >> Change the format to: >> stack depth =3D ... max=3D >> >> In case the subprog name is not specified, use subprog[N] as the string. >> >> Suggested-by: Andrii Nakryiko >> Signed-off-by: Kumar Kartikeya Dwivedi >> --- >> =C2=A0kernel/bpf/verifier.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 | 16 ++++++++++++---- >> =C2=A0.../bpf/progs/verifier_basic_stack.c=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0 |=C2=A0 4 ++-- >> =C2=A0.../bpf/progs/verifier_bpf_fastcall.c=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0 | 19 +++++++++++-------- >> =C2=A0.../bpf/progs/verifier_private_stack.c=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0 |=C2=A0 9 ++++++--- >> =C2=A0.../selftests/bpf/progs/verifier_var_off.c=C2=A0=C2=A0=C2=A0 |=C2= =A0 4 ++-- >> =C2=A05 files changed, 33 insertions(+), 19 deletions(-) >> >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >> index 8d0635ee48c7..51ac0a9ae339 100644 >> --- a/kernel/bpf/verifier.c >> +++ b/kernel/bpf/verifier.c >> @@ -18703,10 +18703,18 @@ static void print_verification_stats(struct bp= f_verifier_env *env) >> =C2=A0 if (env->log.level & BPF_LOG_STATS) { >> =C2=A0 verbose(env, "verification time %lld usec\n", >> =C2=A0 div_u64(env->verification_time, 1000)); >> - verbose(env, "stack depth %d", env->subprog_info[0].stack_depth); >> - for (i =3D 1; i < subprog_cnt; i++) >> - verbose(env, "+%d", env->subprog_info[i].stack_depth); >> - verbose(env, " max %d\n", env->max_stack_depth); >> + verbose(env, "stack depth"); >> + for (i =3D 0; i < subprog_cnt; i++) { >> + const char *name =3D env->subprog_info[i].name; >> + >> + if (name && name[0]) >> + verbose(env, " %s=3D%d", name, >> + env->subprog_info[i].stack_depth); >> + else >> + verbose(env, " subprog[%d]=3D%d", i, >> + env->subprog_info[i].stack_depth); > > That would be not very convenient to parse by veristat, > but I'd print every subprogram on it's own line. > I can do that, but let's agree on the format before I get to it. How should it look like? Prefix with stack depth every line, and print stac= k depth max ... as the very first line? Like so: stack depth max N stack depth subprog 0 N ... stack depth subprog N N ? >> + } >> + verbose(env, " max=3D%d\n", env->max_stack_depth); > > I think check_max_stack_depth_subprog() needs a similar update, > at the moment it reports a not very helpful error like this: > > combined stack size of 34 calls is 528. Too large > > Printing the offending spine would be helpful. > I'll do that in verifier errors patch set. This is just for the verificatio= n stats, that are outside its scope. > ...