From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta1.migadu.com (mta1.migadu.com [37.59.57.117]) (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 2AF561474CC for ; Sun, 9 Aug 2026 17:11:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=37.59.57.117 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786295473; cv=none; b=c+kz/aI7vQ7M5qOahHR3uf37JNduSyKykVahemL+9Nv7aJFDrqo5dnLKIF12AT+AS6/6R3Xf/J1KWvFfua1hsJCnLdm+ESj4qFuHkRpEaIynItQjoKeeUgyPzMPdxnGowDAd2wjnX26mjJDsqgNcC4W7Tu/6RGEG0ep2e/phZB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786295473; c=relaxed/simple; bh=c1gUrWjTy4h7QtYQ5HE07DtR8x4SaBsVSQpOeOpvmlg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=OywENF7QeN/bOIS1ARqVuEJ7J0IhmfCc3rejBhQgbyhxu+VK5MzuM1Z6AHZ1qMcfKah6POptPSNiLscYkR/ZYfw2m3KKf6EBbCgKnlH5EEY/hfNObyUTP0HUVOdQ5sGcnhA3MKdDKsQFTO3IItPjNt4wbgbLor7/CjpH99AVxlE= 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=gfpXjL+M; arc=none smtp.client-ip=37.59.57.117 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="gfpXjL+M" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1786295469; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XpBp+WbQsCcpWpuQO9GCleO3iIrhhT4MJgEdXq+DRcE=; b=gfpXjL+MZ850Mbfg64iLeZ+NLNghktQm360N/y4elGeAiH6y987ivzhNKwGku7ImCyYw65 Y/3P083F+8F1bZbk8D0t9O/tZZb84u0mZx7eVk0v8JYs0MS1TRbhmf/GnB6EkAB/ascWrK RmXpec829QDivW0WHgqPvNIU260g258= 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 v3 1/4] rv/reactors: use context-sensitive lockdep wait type in rv_react() Date: Mon, 10 Aug 2026 01:10:38 +0800 Message-Id: <26526e555baa5118325b2383e9f7f0f8f9b6a199.1786294920.git.wen.yang@linux.dev> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-trace-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 X-Migadu-Flow: FLOW_OUT From: Wen Yang Reactors must not explicitly take locks, so they should comply with LD_WAIT_FREE. However, reactor callbacks can run with preemption enabled on any kernel (not just PREEMPT_RT). If a timer interrupt fires during the callback, the interrupt exit path schedules and acquires rq->__lock (LD_WAIT_SPIN) while the lockdep override map that declared LD_WAIT_FREE is still held, triggering 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} Fixes: 69d8895cb9a9 ("rv: Add explicit lockdep context for reactors") Suggested-by: Gabriele Monaco Signed-off-by: Wen Yang Cc: Thomas Weißschuh --- kernel/trace/rv/rv_reactors.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/kernel/trace/rv/rv_reactors.c b/kernel/trace/rv/rv_reactors.c index 2f5fc8d18dea..5830229210e8 100644 --- a/kernel/trace/rv/rv_reactors.c +++ b/kernel/trace/rv/rv_reactors.c @@ -465,18 +465,28 @@ 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 in preemptible contexts to avoid false-positive lockdep + * reports; keep LD_WAIT_FREE in NMI/hardirq where preemption is + * disabled and the scheduler cannot run. + */ + static DEFINE_WAIT_OVERRIDE_MAP(rv_react_map, LD_WAIT_SPIN); + static DEFINE_WAIT_OVERRIDE_MAP(rv_react_map_atomic, LD_WAIT_FREE); + struct lockdep_map * __maybe_unused map; va_list args; if (!rv_reacting_on() || !monitor->react) return; + map = (in_nmi() || in_hardirq()) ? &rv_react_map_atomic : &rv_react_map; va_start(args, msg); - - lock_map_acquire_try(&rv_react_map); + lock_map_acquire_try(map); monitor->react(msg, args); - lock_map_release(&rv_react_map); - + lock_map_release(map); va_end(args); } EXPORT_SYMBOL_GPL(rv_react); -- 2.25.1