From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=117.135.210.4 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793259310; b=RYSIiWMH9LeiAU3EDIrNT/1sHTZw/C8MUawoAALNqOvtM9IYrv5OCGR7Xk9U2ZDVF7Ll etlJ6qky9M/buAes1mnHA2RFIU5fwOEcBpPsoylI4SwH8mBoUGIcs1Ns4+0DvkxrBRJBt CzjMfVTgO/iccv1v2xNjHb8fgQyPQxhCqa5IACY0RfjWiV3l9K7v4HmmzAmdHp0BSw1mU RT56kNgNH6e7en3a0udZk20JcugUQzXmvz331Av09Tx/MgB1u3T892/fKKTkZsTaHT02M wwncWpcsStxDcHvFjUcsLrkQoEVacim7FWO7wFddVH9ScwGvJHs4h8nYzniiQ2PwFTQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793259310; h=DMARC-Filter:DKIM-Signature:Received:From:To:Cc:Subject:Date: Message-Id:X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding:X-CM-TRANSID:X-Coremail-Antispam: X-CM-SenderInfo; bh=sRoXQOLMcZAIEFXJdx6jUj5MNy5hDFeGder7q1cCC+k=; b=krsrS2Zr9EU+lZw/qpyQsZTFJcbrN2bUhBPjbgw9LjK+EIpR6LSdbpbdMfpfQEcFuDmH nVQqnr7mpNbNJTIFpEp6f0+CviZ9NgZ4xSB5qk+qFO5DdIbhZYE/NNQ0BlL4t8k2gp6og gIYSwdy1c28hOqf3zVAp/2241Wq3WZ3xD+jyoKHtHwmnvIXFf/lTlmmngkEDR3IFQPaDY Wxvjqd8vHukTJbKWn2qZb0XK8cpL2uSAAmyVPB9U/dJqxIGLNwOqbBrlsaVUPl7v1ru9y knTjHFjKnswZ+HtgLrigHZWBGYI6gVsHqGDqXPM2kyHdXt7gvcRpeY0pRo5j6s0ZxwA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass header.d=163.com header.i=@163.com header.a=rsa-sha256 header.s=s110527 header.b=QR750SsO; arc=none smtp.remote-ip=117.135.210.4 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 219B6606A32A; Thu, 29 Oct 2026 07:35:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 219B6606A32A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=163.com header.i=@163.com header.a=rsa-sha256 header.s=s110527 header.b=QR750SsO DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=sR oXQOLMcZAIEFXJdx6jUj5MNy5hDFeGder7q1cCC+k=; b=QR750SsOf1DZIgPHzd /TDXBV8N6t7pbIn2YAJRhOgICMYTjR4trMl/Khm8/1/EHeiAWqyGU9BZGbMdkT0S rZeZbf3Ap9OXFMMKd7hfRHiYFEucAAsFwMdoXU/Q1J4YINzOKw3/NFXyKEcQLpq0 wQRT2JID+Ub4g8UKEYM0jhVSs= Received: from localhost.localdomain (unknown []) by gzsmtp5 (Coremail) with SMTP id QCgvCgBXMJHY9uJqilfyCg--.26815S2; Thu, 29 Oct 2026 15:33:46 +0800 (CST) From: Feng Yang To: yangsongsen@insta360.com Cc: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, emil@etsalapatis.com, ihor.solodrai@linux.dev, jolsa@kernel.org, kpsingh@kernel.org, linux-trace-kernel@vger.kernel.org, martin.lau@linux.dev, mathieu.desnoyers@efficios.com, matt@bobrowski.net, memxor@gmail.com, mhiramat@kernel.org, rostedt@goodmis.org, song@kernel.org, yangfeng59949@163.com, yonghong.song@linux.dev Subject: Re: [PATCH bpf-next] bpf: Fix suspicious RCU usage for sleepable bpf_get_stack() Date: Thu, 29 Oct 2026 15:33:44 +0800 Message-Id: <20261029073344.729148-1-yangfeng59949@163.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261028125148.1348-1-yangsongsen@insta360.com> References: <20261028125148.1348-1-yangsongsen@insta360.com> X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:QCgvCgBXMJHY9uJqilfyCg--.26815S2 X-Coremail-Antispam: 1Uf129KBjvdXoW7JFy3try7XFy7WFyfAF17Awb_yoWftwb_ur WqvFn7GasYqrWvyan3Gw13Xr9xK3yYqr1xGFW0q3sIvry3Ja4kZayvv3s3X3y3Xw48tryv vFZxWw1jgFyS9jkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7sR_uyxtUUUUU== X-CM-SenderInfo: p1dqww5hqjkmqzuzqiywtou0bp/xtbCzxtHv2ri9ttuLQAA3K On Wed, 28 Oct 2026 20:51:47 +0800, Songsen Yang wrote: > Hi Feng, > > I hit the same root cause independently via syzbot and sent a fix a > few hours after yours, without having seen this patch -- sorry for the > overlap: > > https://lore.kernel.org/bpf/20261028121859.994-1-yangsongsen@insta360.com/ Hi Songsen, Please don't worry about the overlap. I hadn't noticed the issue Sashiko raised when I prepared my fix; It looks like a pt_regs on the stack can fix this.: BPF_CALL_4(bpf_get_stack_raw_tp_sleepable, struct bpf_raw_tracepoint_args *, args, void *, buf, u32, size, u64, flags) { struct pt_regs regs; perf_fetch_caller_regs(®s); return bpf_get_stack_sleepable((unsigned long) ®s, (unsigned long) buf, (unsigned long) size, flags, 0); } That said, I think your approach is the simpler one and the better fit for the fix itself. So if the maintainers prefer your version, feel free to ignore my patch. Thanks, Feng