From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7A77347CC99; Tue, 16 Jun 2026 17:52:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781632326; cv=none; b=bS0e6ePeAl1dz8UgMAu0JBZqqS7Pu79mlgGmqjiuUZqi4mt24gs545/AvVNjkahisFREYlUd7j0M57iObxePV9vhQPg1ZYwMIe8fG5OAxnC5M5ykKUBGWKZnP0KY85srk107GJ5n8lJTHMcHGPsQQkPU2ZTRHw2CnxToxkAMIWc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781632326; c=relaxed/simple; bh=nTEFo2Ahf9W+dS7LPdwwFai39chQnqgqvk4nlIa+muM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AtkrKhcld83T4C0Rc80G9w++cnbT/hMktN2E1qziOwkGUCVgRwmgTTg1Lovgfuo5rWl7RM1QxR543QCjUk71wlejKYV7VSE7wxSwh4E1BLErhmiOqHLV3EAy4dUYFK0ynODrPvZFJQBWF7mOTwwy4gYxIfEppocDWhWbUE2RhxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=z12+SKK9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="z12+SKK9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF3901F000E9; Tue, 16 Jun 2026 17:51:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781632320; bh=fAUS/8pQP0SRpy8KRX2mr/CgNmKFUnf+qI2U+6HBmco=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=z12+SKK9hNpj0iIsAaA+SI3UlW094SeADihUouwFv08kY2fqH4W/48NboApBIpaOB EZDkfSHaNPb/SchhLKBVeeyBROLCK61/g4TCLgRBXirVuytVYXutRYGLUdTmmT0OcX Y4o42dqRdD5jBAHKy4k2Me1FMGq1MZFrLT4ECBUA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masami Hiramatsu , Mathieu Desnoyers , David Carlier , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.1 371/522] tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func() Date: Tue, 16 Jun 2026 20:28:38 +0530 Message-ID: <20260616145143.131003643@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145125.307082728@linuxfoundation.org> References: <20260616145125.307082728@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier [ Upstream commit fad217e16fded7f3c09f8637b0f6a224d58b5f2e ] When a tracepoint goes through the 0 -> 1 transition, tracepoint_add_func() invokes the subsystem's ext->regfunc() before attempting to install the new probe via func_add(). If func_add() then fails (for example, when allocate_probes() cannot allocate a new probe array under memory pressure and returns -ENOMEM), the function returns the error without calling the matching ext->unregfunc(), leaving the side effects of regfunc() behind with no installed probe to justify them. For syscall tracepoints this is particularly unpleasant: syscall_regfunc() bumps sys_tracepoint_refcount and sets SYSCALL_TRACEPOINT on every task. After a leaked failure, the refcount is stuck at a non-zero value with no consumer, and every task continues paying the syscall trace entry/exit overhead until reboot. Other subsystems providing regfunc()/unregfunc() pairs exhibit similarly scoped persistent state. Mirror the existing 1 -> 0 cleanup and call ext->unregfunc() in the func_add() error path, gated on the same condition used there so the unwind is symmetric with the registration. Fixes: 8cf868affdc4 ("tracing: Have the reg function allow to fail") Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://patch.msgid.link/20260413190601.21993-1-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt (Google) [ changed `tp->ext->unregfunc` to `tp->unregfunc` to match older struct layout ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/tracepoint.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -337,6 +337,8 @@ static int tracepoint_add_func(struct tr lockdep_is_held(&tracepoints_mutex)); old = func_add(&tp_funcs, func, prio); if (IS_ERR(old)) { + if (tp->unregfunc && !static_key_enabled(&tp->key)) + tp->unregfunc(); WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM); return PTR_ERR(old); }