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 55925318EDF for ; Sun, 10 May 2026 17:21:02 +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=1778433662; cv=none; b=MP6nTG1n+/LegnR4ZY/1JEf6DGPkm6JfxDkeDpHTIeWm8sCp0NrpKNR+oKy3lQuWRLOhVNlYNb5/RYEhWfFoQB6DklX8ylTeE1hLyRfj22jVtTOBKBzVuRG5huv+314+5sWS9ZGxxLinNVFgXs8xoKOGhEqtUr912IHQcUs4W6E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778433662; c=relaxed/simple; bh=zZMRldj5q6qkXLfwQJe5x/yFY69U0+S9rz0/WVSfKj0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qLEJaY04i8R2wKuS8PntjJhPq6UzRxc/mxEiJ9TifV/TRVi6EavSH8AAS2lRLx8pdlz0GqsPWfyOmH4aCf6nMJMyBBaGd1ZmIaHzM7Lw6ijNQJa3uVBsO8Z1PWjEKLQLLGPpGOUvX71du1bfOTxnARJuP4/rPMz+BLj+PcFGlC8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BxqvY8bb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BxqvY8bb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83FA6C2BCB8; Sun, 10 May 2026 17:21:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778433662; bh=zZMRldj5q6qkXLfwQJe5x/yFY69U0+S9rz0/WVSfKj0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BxqvY8bbgx5WThcNS39SP6XgTgYIbk3nr6WFOic91zSx8UpjVEp2ySZVGVIzJqhqp yVS6PIOwHh+6cQrjGlglPpBfRKFOpXmjdZ4zW9foMrH5ikJyWMWknifUkIlBX1JYDv +upbkfa0nj3g+YrnqsT69cluEG4OHmNKUOoxhiVnXhgJ5axm4aVH9xPl7vqtqOF77d F4Q1n0d8P/XTzaBJzvPRsAWK5fuPb6RY5TuQh/lkCUFL8dAHhsm/Pm62psnCmbqsFz EXB6lrgebmw82g1Ci8uW/8EAwmtI6A4e/lWGf4lVbbRXyY4HlGsSBEveMU6xqM+gIK 1FrAzzaPRgHNQ== From: Sasha Levin To: stable@vger.kernel.org Cc: David Carlier , Masami Hiramatsu , Mathieu Desnoyers , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.12.y] tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func() Date: Sun, 10 May 2026 13:20:59 -0400 Message-ID: <20260510172059.533474-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026050743-olive-survey-8b8f@gregkh> References: <2026050743-olive-survey-8b8f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- kernel/tracepoint.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c index 8879da16ef4d6..4cee42ed5fc8d 100644 --- a/kernel/tracepoint.c +++ b/kernel/tracepoint.c @@ -337,6 +337,8 @@ static int tracepoint_add_func(struct tracepoint *tp, 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); } -- 2.53.0