From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pdx-out-004.esa.us-west-2.outbound.mail-perimeter.amazon.com (pdx-out-004.esa.us-west-2.outbound.mail-perimeter.amazon.com [44.246.77.92]) (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 27AE94BFE95; Thu, 1 Oct 2026 23:53:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=44.246.77.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790898784; cv=none; b=ltymVDxQ9MxnfXmHx8xKNH6LLTuG0F7qWGJo7Fy+EHB4EhZSTxUswI4zcJ/9vgnAiUms14z/EeSbDu0CzhXYFNfRot5G24tubOTiqTro3hiGLW5D5Hbj1eGXBFR2+cKJiRvMy9su4/JtkKsr58lI6TFd2Qx98JcHCWyuBjNC2xw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790898784; c=relaxed/simple; bh=/veSFjfpDTvESgnF+9YOuO5Zbjr+NstFT32TDXd2PrY=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aPg40wF5sExeLkiD+rmQlc988gps3qg9ra9AEf3SJUTPGi5PPvxwP4INQVO4s3+JnhLAtZFm+rE9MSMjKCnPswIb9a+oHAHsanO8LWpqMZSx13ySHQHifQSC6PwbclIzAlhDPaQkiOr+Qubd8EVjJ/fQzzhfgai9IzIion9wn3k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=fkWHkcZU; arc=none smtp.client-ip=44.246.77.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="fkWHkcZU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1790898783; x=1822434783; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kxANHnSNVsfo3V4BZi+LzUk1TCDNoWGyrIauKbRV8tU=; b=fkWHkcZU+CO5EHTs/ocYxLC9Na/oNcYlzpzOFJafHcmnFGSeyvpWIZNs xTbuOnPKi9jV5Dwl5K+DXLeqoAyRiK6VC5th06sUa3lVVfKeWhfTjcTSH S3GqboWkUnrIsxtHRcnHulbo5hlW8UAP47M6U2SantVWp3Wvxc2AUpmY8 nyEuOdwkQieIUcuURzLHDDXJC+y7/Gs1j91/OWDb0bjvm7TaZuoW1dG/G NqMYPBRb9cMFwD/+jZZypivM0nFltWTVIDEZT0XQJ02lcFoLtbNl22Ch2 hm4S9yy9kZqeIIMY79m4FfaJAWw9EX22KfDJiFUKIjzMgXGRXb//sSWZy Q==; X-CSE-ConnectionGUID: ptytDu1ySeKuSb/4yPeISQ== X-CSE-MsgGUID: Uwuct7xkTcCCJ1tokDDJLQ== X-IronPort-AV: E=Sophos;i="6.27,135,1787011200"; d="scan'208";a="30183707" Received: from ip-10-5-0-115.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.0.115]) by internal-pdx-out-004.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2026 23:53:02 +0000 Received: from EX19MTAUWC001.ant.amazon.com [205.251.233.105:1540] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.37.83:2525] with esmtp (Farcaster) id 57b5f7b1-3a2c-421b-8838-145ea894ae32; Thu, 1 Oct 2026 23:53:02 +0000 (UTC) X-Farcaster-Flow-ID: 57b5f7b1-3a2c-421b-8838-145ea894ae32 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWC001.ant.amazon.com (10.250.64.174) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.49; Thu, 1 Oct 2026 23:53:02 +0000 Received: from dev-dsk-wanjay-2c-d25651b4.us-west-2.amazon.com (172.19.198.4) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.49; Thu, 1 Oct 2026 23:53:01 +0000 From: Jay Wang To: , , , , , , CC: , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH bpf-next v3 8/9] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate Date: Thu, 1 Oct 2026 23:53:01 +0000 Message-ID: <20261001235301.7224-1-wanjay@amazon.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <973216fc6e2c9c225b847f0f82941b5e1e2d49944c2b16ff5cbcdcdf2910e8d6@mail.kernel.org> References: <973216fc6e2c9c225b847f0f82941b5e1e2d49944c2b16ff5cbcdcdf2910e8d6@mail.kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D039UWA003.ant.amazon.com (10.13.139.49) To EX19D001UWA001.ant.amazon.com (10.13.138.214) Right, fixed in v4 (patch 5/12, with the other tracefs and bpffs requests that load the BTF): https://lore.kernel.org/bpf/20261001225214.12351-1-wanjay@amazon.com/ event_btf_ids_read() now calls bpf_load_btf_vmlinux() before it takes event_mutex, so the btf_vmlinux module load and its trace notifier run without it; btf_get_module_btf(NULL) under the mutex then finds the BTF already parsed. More generally, in v4 the lookups themselves never load the BTF any more (see the reply to Alexei on 4/9): the probe argument parser (PROBE_EVENTS_BTF_ARGS) loads it explicitly, holding only dyn_event_ops_mutex, which loading a module never takes. Tested by reading events/sched/sched_switch/btf_ids, and by creating kprobe events with BTF arguments, each as the first BTF user after boot. Jay