From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B28635A941; Fri, 9 Jan 2026 12:10:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767960635; cv=none; b=BqU4Zv/f6hRSfGu80yQETuODp/vvowtx37taqj06w759ZTlETuDnqvrY+8fDSAWGdLrT7ykZNyGEEJ3268x6lEPj9Vy7kaxLWp8VN+b+Rj6eoRu7DDoixdV6wcqqdE84Tk5negayxaueH7krm2/kMh/JlwxSTQqB8vikeuIJUz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767960635; c=relaxed/simple; bh=gMALmwFy0yi14AMMIU1piwNkda3C01xE4+opbr2Fcu8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dGi9dy4usdESj8iBnnbQW9PWZp5gHeZKvFitKVpe4xKqG3bX/U33tskgvHAIvOJlaxf93Yq5ST/5U644bG+nKbkO3qaDEedOyDZ5lNCE/BTBDwTLMDT+YFhzpHP4Z5wQcOf2ICFFH8hh2YqVkHWjmKIAUtdRHYNU5nIQ9EC7TbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T68TatEE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="T68TatEE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EC1BC2BCB3; Fri, 9 Jan 2026 12:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1767960634; bh=gMALmwFy0yi14AMMIU1piwNkda3C01xE4+opbr2Fcu8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T68TatEEQepke8oWVehTxC1MBDviWhxniga2ZxWrf8xEG+TVH8fw2TeOqn2Un3Go/ 5au3WPDL5lpbj4bbzptilSM0+WbQmCflmjUO4BwDpIHm8JO4d2yG6+VhXS2X3ZPu+4 EwHlKdX6vZCbn26R/DqnMf7Y2wEmSZlaHMRGcTxU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Mathieu Desnoyers , Arnaldo Carvalho de Melo , Jiri Olsa , Namhyung Kim , Ian Rogers , "Steven Rostedt (Google)" Subject: [PATCH 6.6 472/737] tracing: Do not register unsupported perf events Date: Fri, 9 Jan 2026 12:40:11 +0100 Message-ID: <20260109112151.742446334@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260109112133.973195406@linuxfoundation.org> References: <20260109112133.973195406@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Steven Rostedt commit ef7f38df890f5dcd2ae62f8dbde191d72f3bebae upstream. Synthetic events currently do not have a function to register perf events. This leads to calling the tracepoint register functions with a NULL function pointer which triggers: ------------[ cut here ]------------ WARNING: kernel/tracepoint.c:175 at tracepoint_add_func+0x357/0x370, CPU#2: perf/2272 Modules linked in: kvm_intel kvm irqbypass CPU: 2 UID: 0 PID: 2272 Comm: perf Not tainted 6.18.0-ftest-11964-ge022764176fc-dirty #323 PREEMPTLAZY Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 RIP: 0010:tracepoint_add_func+0x357/0x370 Code: 28 9c e8 4c 0b f5 ff eb 0f 4c 89 f7 48 c7 c6 80 4d 28 9c e8 ab 89 f4 ff 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc <0f> 0b 49 c7 c6 ea ff ff ff e9 ee fe ff ff 0f 0b e9 f9 fe ff ff 0f RSP: 0018:ffffabc0c44d3c40 EFLAGS: 00010246 RAX: 0000000000000001 RBX: ffff9380aa9e4060 RCX: 0000000000000000 RDX: 000000000000000a RSI: ffffffff9e1d4a98 RDI: ffff937fcf5fd6c8 RBP: 0000000000000001 R08: 0000000000000007 R09: ffff937fcf5fc780 R10: 0000000000000003 R11: ffffffff9c193910 R12: 000000000000000a R13: ffffffff9e1e5888 R14: 0000000000000000 R15: ffffabc0c44d3c78 FS: 00007f6202f5f340(0000) GS:ffff93819f00f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055d3162281a8 CR3: 0000000106a56003 CR4: 0000000000172ef0 Call Trace: tracepoint_probe_register+0x5d/0x90 synth_event_reg+0x3c/0x60 perf_trace_event_init+0x204/0x340 perf_trace_init+0x85/0xd0 perf_tp_event_init+0x2e/0x50 perf_try_init_event+0x6f/0x230 ? perf_event_alloc+0x4bb/0xdc0 perf_event_alloc+0x65a/0xdc0 __se_sys_perf_event_open+0x290/0x9f0 do_syscall_64+0x93/0x7b0 ? entry_SYSCALL_64_after_hwframe+0x76/0x7e ? trace_hardirqs_off+0x53/0xc0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Instead, have the code return -ENODEV, which doesn't warn and has perf error out with: # perf record -e synthetic:futex_wait Error: The sys_perf_event_open() syscall returned with 19 (No such device) for event (synthetic:futex_wait). "dmesg | grep -i perf" may provide additional information. Ideally perf should support synthetic events, but for now just fix the warning. The support can come later. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Namhyung Kim Link: https://patch.msgid.link/20251216182440.147e4453@gandalf.local.home Fixes: 4b147936fa509 ("tracing: Add support for 'synthetic' events") Reported-by: Ian Rogers Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_events.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -689,6 +689,8 @@ int trace_event_reg(struct trace_event_c #ifdef CONFIG_PERF_EVENTS case TRACE_REG_PERF_REGISTER: + if (!call->class->perf_probe) + return -ENODEV; return tracepoint_probe_register(call->tp, call->class->perf_probe, call);