From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.2]) (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 2AAED1A5B8A; Fri, 10 Apr 2026 04:33:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.2 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775795612; cv=none; b=ZxjNMEYN1OpcQqrJcq2j+smQPahaeXb36kkgjhKdrczNfHSu8PyTT6Erami5cmYKhOtA3JF/tU3NWrrgMsjTl/nRM0j+ixt4upTJ/RQwfMUXAmakEVk5F6VSNZkIBjOw6CyDECH6jCnkyNlrl9wqK+RQnNoWVhGKiXBp1DQ1goQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775795612; c=relaxed/simple; bh=SMGsPyxBD/ferwmLgwJAfUSrtW9ZZquY0BZGfcDQGtI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=QoGqLusPS9JViYmjMS9jvqIhwr6aPBN7PkQ1TwM5I7OUhz6Tkb0J0O0kP6VAprJupkwf0x6/xVTM1gG1vci7YuLgwvV35UYYnOZg8uZklnK+jCk988rcf7kKIhqFTy8seLisCFI/OInSQC+KAyCdExnuktUKFFuIavOgRi15PDc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=csSv6NPg; arc=none smtp.client-ip=220.197.31.2 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) header.d=163.com header.i=@163.com header.b="csSv6NPg" 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=yI Pgk9Fvc5GGb1n+c5WvNVrrivP3Qxx7uj2ePzLbvCE=; b=csSv6NPgQ8WBTudhut WmlG+w3NqlmDNrE5Id0ORKCp5S3rtOaJfTS6WpOXLAgML++Hb8QHSCXmxM0m3t1r urTEyxZD6o+xR1fMYI3tECGnZ35VKKtYeQXLm8KmCSWA7nagnVDmgY/MqRYJWzos 08Px+KWQWcbYIW47pMcTEhWp4= Received: from localhost.localdomain (unknown []) by gzsmtp3 (Coremail) with SMTP id PigvCgDX38lufdhpbcrDAQ--.9S2; Fri, 10 Apr 2026 12:32:51 +0800 (CST) From: Cao Ruichuang To: Masami Hiramatsu Cc: Cao Ruichuang , rostedt@goodmis.org, mathieu.desnoyers@efficios.com, shuah@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH] selftests/ftrace: Account for fprobe attachment at creation Date: Fri, 10 Apr 2026 12:32:43 +0800 Message-Id: <20260410043243.65800-1-create0818@163.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20260409172955.98e2d20a7f7736a1a9834816@kernel.org> References: <20260407115751.96184-1-create0818@163.com> <20260409172955.98e2d20a7f7736a1a9834816@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 X-CM-TRANSID:PigvCgDX38lufdhpbcrDAQ--.9S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Ar17JF43JryrGrWDtrW8WFg_yoW8Jw15pa 9Ykwn8Kr1kta4rKa9xXw1FkFn5ArZrXrs8GF97G393Ww1DZF1kJw4vvF47XF1jvrWkGF1Y gF4FgF1Fqw45Aa7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0JUemhrUUUUU= X-CM-SenderInfo: pfuht3jhqyimi6rwjhhfrp/xtbCwBMMRWnYfXNeuAAA3D Hi Masami, I reran this in clean QEMU on two kernels and got different results. 1. Ubuntu distro kernel: Linux 6.8.0-100-generic #100-Ubuntu SMP PREEMPT_DYNAMIC Tue Jan 13 16:40:06 UTC 2026 baseline count=2 after_create123 count=4 after_enable1/2/3 count=4 baseline enabled_functions: __hid_bpf_tail_call ... after_create123 enabled_functions: kernel_clone (2) R ->arch_ftrace_ops_list_func+0x0/0x280 kmem_cache_free (1) R tramp: ... ->fprobe_handler+0x0/0x40 __hid_bpf_tail_call ... 2. Current source-tree kernel built from the clean snapshot of my patch branch: Linux 7.0.0-rc6 #2 SMP PREEMPT_DYNAMIC Fri Apr 10 12:19:39 CST 2026 baseline count=0 after_create123 count=0 after_enable1 count=1 after_enable2 count=1 after_enable3 count=2 after_create123 enabled_functions: after_enable3 enabled_functions: kernel_clone (2) ->arch_ftrace_ops_list_func+0x0/0x200 kmem_cache_free (1) tramp: ... ->fprobe_ftrace_entry+0x0/0x220 So the behavior I reported earlier reproduces on that Ubuntu 6.8 kernel, but not on the current source-tree kernel. I think my earlier conclusion was too broad. I will stop pushing this testcase change for now unless I can narrow down which kernel change caused the difference. Thanks, Cao Ruichuang