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 49FDE17555 for ; Mon, 11 May 2026 00:10:45 +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=1778458245; cv=none; b=EGzndz3YUM9ZBbiTHXxBeNqxwFX4Q/cFWvvOzICsI+n3fFm4f9XeBLMpX1CPz84XxZVjZgQAiq9NG6EiJdMzgRVWjVLNcna+3OGLW0l/8lp/ooJjhZv7m1F93vY+350f65evqu3Q5a1NEGgTH1oFakEW+sLnTMQ4o8hvVjroaLg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778458245; c=relaxed/simple; bh=PIQB7f+i8B4/HR/HNgSpGS+oPjjGp4gkP/dIJjlaSaY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f1rw/+AVNA8st/OMQX3iRNwoqsf+d/wBBZeOJDSqFiwE7wy6ZjmLfGCvcKdBiLgoYgbaeCOOzFn/zpnbMzidxYcgshJg59j8iQqxMKvEVCP67wOqvFJKwODJQaLmUSuqC0AoTljh/mZvDy4iVjiB9Wqc6YiXmnhmfv364Wd4p/4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qPEmsLm5; 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="qPEmsLm5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 439A8C2BCB8; Mon, 11 May 2026 00:10:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778458244; bh=PIQB7f+i8B4/HR/HNgSpGS+oPjjGp4gkP/dIJjlaSaY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qPEmsLm5uF+BLyhTcO2uxn6w2nmHMtNjG4GVS53MXY2V0AgOMDO5Rgh66NVSS/UZF FYRrXEEuL7zsLPxY7lnQG/15TAcmdEn61C+2fc3ou9zoCFZ65DA2hqmhB7fOJcBEmL 6tp9fQuVVANBYLI5ZAj6o8Va8oP052j6SqFhzeFK7S6QmZ7hh5xrMmaQkN98Ulx2Sj fyRh4zjGXAMpP6gyBs7MDam8cvKCzg0C2nYP/WD6lG/9wO9Lu1iJbnNl915KAnZnLL Hcev5Rvw8ju/8R/KZxPMHo7Sc9YfZSOwL725g/lYhiOqx0CHqdZK7NGmzVs+vw4gET eLyGPB7Jn5ZTw== From: Sasha Levin To: stable@vger.kernel.org Cc: David Carlier , Masami Hiramatsu , Mathieu Desnoyers , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 6.1.y] tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func() Date: Sun, 10 May 2026 20:10:41 -0400 Message-ID: <20260511001041.752593-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026050736-pelican-vendor-20aa@gregkh> References: <2026050736-pelican-vendor-20aa@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 f23144af57430..55af3586371c2 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