From: Jiri Olsa <olsajiri@gmail.com>
To: bot+bpf-ci@kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
kafai@fb.com, eddyz87@gmail.com, songliubraving@fb.com,
yhs@fb.com, menglong8.dong@gmail.com, rostedt@kernel.org,
martin.lau@kernel.org, yonghong.song@linux.dev, clm@meta.com,
ihor.solodrai@linux.dev
Subject: Re: [PATCHv7 bpf-next 13/29] bpf: Add support for tracing multi link
Date: Thu, 4 Jun 2026 10:00:23 +0200 [thread overview]
Message-ID: <aiEwl5axWo8_V7cR@krava> (raw)
In-Reply-To: <6e738b0697b9ee06e9cbaa325a3330f0447f4cd12ae54d6b2c82365d58c4c525@mail.kernel.org>
On Wed, Jun 03, 2026 at 11:52:13AM +0000, bot+bpf-ci@kernel.org wrote:
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index d853f97bd154..9e3cb547651e 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -42,6 +42,7 @@
> >
> > #define MAX_UPROBE_MULTI_CNT (1U << 20)
> > #define MAX_KPROBE_MULTI_CNT (1U << 20)
> > +#define MAX_TRACING_MULTI_CNT (1U << 20)
>
> [ ... ]
>
> > @@ -3641,3 +3642,132 @@ __bpf_kfunc int bpf_copy_from_user_task_str_dynptr(const struct bpf_dynptr *dptr
>
> [ ... ]
>
> > +static int check_dup_ids(u32 *ids, u32 cnt)
> > +{
> > + int err = 0;
> > +
> > + /*
> > + * Sort ids array (together with cookies array if defined)
> > + * and check it for duplicates. The ids and cookies arrays
> > + * are left sorted.
> > + */
> > + sort_r_nonatomic(ids, cnt, sizeof(ids[0]), ids_cmp_r, ids_swap_r, NULL);
>
> The sort here can run over up to MAX_TRACING_MULTI_CNT (1 << 20) elements
> without ever yielding the CPU. Can this hold the CPU long enough to trip
> RCU stalls or the soft lockup watchdog when cnt is large?
>
> This was raised on an earlier posting of the series, with the suggestion
> to add a cond_resched() somewhere in the path. The reply noted that in
> practice the count is expected to be closer to 100k rather than the full
> 1M limit, and that it was unclear where the cond_resched() should go, so
> the code was left as is. Since MAX_TRACING_MULTI_CNT is still 1 << 20,
> would it be worth revisiting whether a reschedule point is needed here?
we now use sort_r_nonatomic which calls cond_resched,
I don't think loop below needs the cond_resched call
jirka
>
> > +
> > + for (int i = 1; i < cnt; i++) {
> > + if (ids[i] == ids[i - 1]) {
> > + err = -EINVAL;
> > + break;
> > + }
> > + }
> > + return err;
> > +}
>
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/26881310426
next prev parent reply other threads:[~2026-06-04 8:00 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 11:05 [PATCHv7 bpf-next 00/29] bpf: tracing_multi link Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 01/29] ftrace: Add ftrace_hash_count function Jiri Olsa
2026-06-03 11:26 ` sashiko-bot
2026-06-04 7:59 ` Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 02/29] ftrace: Add ftrace_hash_remove function Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 03/29] ftrace: Add add_ftrace_hash_entry function Jiri Olsa
2026-06-09 14:29 ` Steven Rostedt
2026-06-09 14:43 ` Kumar Kartikeya Dwivedi
2026-06-10 15:35 ` Steven Rostedt
2026-06-10 15:42 ` Alexei Starovoitov
2026-06-03 11:05 ` [PATCHv7 bpf-next 04/29] bpf: Use mutex lock pool for bpf trampolines Jiri Olsa
2026-06-03 11:28 ` sashiko-bot
2026-06-04 7:59 ` Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 05/29] bpf: Add struct bpf_trampoline_ops object Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 06/29] bpf: Move trampoline image setup into bpf_trampoline_ops callbacks Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 07/29] bpf: Add bpf_trampoline_add/remove_prog functions Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 08/29] bpf: Add struct bpf_tramp_node object Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 09/29] bpf: Factor fsession link to use struct bpf_tramp_node Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 10/29] bpf: Add multi tracing attach types Jiri Olsa
2026-06-03 11:37 ` sashiko-bot
2026-06-04 8:00 ` Jiri Olsa
2026-06-03 11:52 ` bot+bpf-ci
2026-06-03 11:05 ` [PATCHv7 bpf-next 11/29] bpf: Move sleepable verification code to btf_id_allow_sleepable Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 12/29] bpf: Add bpf_trampoline_multi_attach/detach functions Jiri Olsa
2026-06-03 11:52 ` bot+bpf-ci
2026-06-03 11:05 ` [PATCHv7 bpf-next 13/29] bpf: Add support for tracing multi link Jiri Olsa
2026-06-03 11:41 ` sashiko-bot
2026-06-04 8:00 ` Jiri Olsa
2026-06-03 11:52 ` bot+bpf-ci
2026-06-04 8:00 ` Jiri Olsa [this message]
2026-06-03 11:05 ` [PATCHv7 bpf-next 14/29] bpf: Add support for tracing_multi link cookies Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 15/29] bpf: Add support for tracing_multi link session Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 16/29] bpf: Add support for tracing_multi link fdinfo Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 17/29] libbpf: Add bpf_object_cleanup_btf function Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 18/29] libbpf: Add bpf_link_create support for tracing_multi link Jiri Olsa
2026-06-03 11:34 ` sashiko-bot
2026-06-04 7:59 ` Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 19/29] libbpf: Add btf_type_is_traceable_func function Jiri Olsa
2026-06-03 11:36 ` sashiko-bot
2026-06-04 7:59 ` Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 20/29] libbpf: Add support to create tracing multi link Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 21/29] selftests/bpf: Add tracing multi skel/pattern/ids attach tests Jiri Olsa
2026-06-03 13:40 ` sashiko-bot
2026-06-04 8:00 ` Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 22/29] selftests/bpf: Add tracing multi skel/pattern/ids module " Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 23/29] selftests/bpf: Add tracing multi intersect tests Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 24/29] selftests/bpf: Add tracing multi cookies test Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 25/29] selftests/bpf: Add tracing multi session test Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 26/29] selftests/bpf: Add tracing multi attach fails test Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 27/29] selftests/bpf: Add tracing multi verifier " Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 28/29] selftests/bpf: Add tracing multi attach benchmark test Jiri Olsa
2026-06-03 11:05 ` [PATCHv7 bpf-next 29/29] selftests/bpf: Add tracing multi attach rollback tests Jiri Olsa
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