From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-73.mta0.migadu.com [91.218.175.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A3F09399013 for ; Mon, 14 Sep 2026 19:13:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789413241; cv=none; b=B87QNrkZ3Zc/HVrhQSdcfHysDq1ByZImTuEJS/lytKNBvhs+M1IHLvKwSWUmETHt/lZ6mWvByaLimANyJmPYxHZ5b75jw5QWk6NwMI+duM32obvHZixHFWueon5qWvgpK1es7JeaBZp05HaUk6BZEnrtwunUd9occ9ZlXmwPHFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789413241; c=relaxed/simple; bh=+4kR8MIFX6t5QidLegcaQ2NHPJ54cO3nz9NAO9k7Jtc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=icUdCCXQnBRFVoZqVOUVpM3QhH4ydUW+A9C/Rxe2xTm628fvyV4h20t/NfXQ5v93doxqRfxHcxUYu1oRt97LuwzTD4vxYOG045YwyaCacxdwuJg15PLAbl7v32a4dzPoq9UKoBaZM9kB3m45FGHR2Om+cLnfiRSaNaMUytoYNtE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FLJAM3Hg; arc=none smtp.client-ip=91.218.175.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FLJAM3Hg" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=+4kR8MIFX6t5QidLegcaQ2NHPJ54cO3nz9NAO9k7Jtc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1789413234; v=1; x=1790018034; b=FLJAM3HgLUre2b7FRUVga6aPVoCsw03u17EeF6gxeC5+5r/VceviZN+JqBk/HL4pyQuC1Oid GF0ZWsqp2iogor2TXJbEX4QIhy6szGpFst6jDrGz62EHOlQUyuCwlr2D+/oSd+ObaMEbIaAghwM KXEoTOx6evekxP74FPbXQgzc= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id 72d3a83f1702b20c; Mon, 14 Sep 2026 19:13:54 +0000 X-Mizu-Trace-ID: 72d3a83f1702b20c X-Migadu-Flow: FLOW_OUT From: wen.yang@linux.dev To: Gabriele Monaco Cc: Nam Cao , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Wen Yang , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Subject: [PATCH v6 1/4] rv/reactors: use LD_WAIT_SPIN as the reactor lockdep wait type Date: Tue, 15 Sep 2026 03:13:34 +0800 Message-Id: <5586dd00789a0f904cc299cd8889744b8c6f8dc9.1789412799.git.wen.yang@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Wen Yang rv_react() overrides the lockdep wait type to LD_WAIT_FREE to enforce that reactor callbacks take no locks. But callbacks run in the context of the triggering tracepoint, which can be preemptible task context on any kernel. A timer interrupt firing during the callback makes the interrupt-exit path schedule and take rq->__lock (LD_WAIT_SPIN) while the LD_WAIT_FREE override is still held, producing a spurious "Invalid wait context" warning: [ BUG: Invalid wait context ] context-{5:5} 1 lock held by kunit_try_catch/209: #0: (rv_react_map-wait-type-override){+.+.}-{1:1} kunit_try_catch/209 is trying to lock: ffff8a743ed3e8a0 (&rq->__lock){-...}-{2:2} Use LD_WAIT_SPIN instead of LD_WAIT_FREE, which causes false-positive warnings in preemptible contexts due to scheduler preemption taking rq->__lock. Fixes: 69d8895cb9a9 ("rv: Add explicit lockdep context for reactors") Reviewed-by: Gabriele Monaco Signed-off-by: Wen Yang Cc: Thomas Weißschuh --- kernel/trace/rv/rv_reactors.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/trace/rv/rv_reactors.c b/kernel/trace/rv/rv_reactors.c index 2f5fc8d18dea..ff7d478227c3 100644 --- a/kernel/trace/rv/rv_reactors.c +++ b/kernel/trace/rv/rv_reactors.c @@ -465,7 +465,15 @@ int init_rv_reactors(struct dentry *root_dir) void rv_react(struct rv_monitor *monitor, const char *msg, ...) { - static DEFINE_WAIT_OVERRIDE_MAP(rv_react_map, LD_WAIT_FREE); + /* + * Reactors must not explicitly take locks, so they should be + * LD_WAIT_FREE. However, reactor callbacks can run with preemption + * enabled, meaning the preempting code (e.g. the scheduler taking + * rq->__lock at LD_WAIT_SPIN) may violate that constraint. Use + * LD_WAIT_SPIN to avoid false-positive lockdep reports. + * But you should still NOT be using locks in reactors. + */ + static DEFINE_WAIT_OVERRIDE_MAP(rv_react_map, LD_WAIT_SPIN); va_list args; if (!rv_reacting_on() || !monitor->react) -- 2.25.1