From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-185.mta1.migadu.com (out-185.mta1.migadu.com [95.215.58.185]) (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 92E8B3D6682 for ; Sun, 9 Aug 2026 17:11:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.185 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786295482; cv=none; b=gGdc5yaPB2oaKo19W2ErwNvElHoG4Cpt9OY1HxQZBudqSNfSJu0MVeZ/yUww5mqPLzO7q6MvT+Y5PMkO2YAlMmfl0X64N9syWseZA/Mf0LVY1zAbw2DPKbsU907d+bV18GNJBD1p39TfA57ZsMWRk+Z5nvHXPFb0VMphy1j8umE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786295482; c=relaxed/simple; bh=41cfatl71cR5zJ3hrhQdWxiYN42mLzQ/yO0upW5f2NM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=UECd74n8/XetXW+01h8lYAPUtMxTINKNP3qOqiS5snjjZC/MoIMQ+hvT8GA9PZcojZqUWu3Im63+y39EBoskTI7nQCLZJD3UtMWv0K5rmY6fBAfUovLj2av3B+b/74nDjdOy1WH2RPrDUeuejg8PpSgrWAwmJ4uLuKBSgWEM+b4= 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=w0Z66gnt; arc=none smtp.client-ip=95.215.58.185 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="w0Z66gnt" 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=1786295466; 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; bh=PRyewFmNXjglDR9PnGZbqs5K4K3sd/JST9jCUvtJSxs=; b=w0Z66gntONlZFswFqy2CSWup/7FwkMY1N92SUYLyYXlwboqAMfM1jTeWlgf7paw2RFy5Yy BBoLZepmHo4XnSHaT9edD5/g7kq5AtqfjswWhTSIZWS1P/DwrCTwgrO+gVV4Grm+5/HNV8 guR4QhGDbg2WIjr8V67SdTfFQ6rN9KI= From: wen.yang@linux.dev To: Gabriele Monaco Cc: Nam Cao , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, Wen Yang Subject: [PATCH v3 0/4] rv/reactors: fix lockdep warning and add KUnit tests Date: Mon, 10 Aug 2026 01:10:37 +0800 Message-Id: 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 X-Migadu-Flow: FLOW_OUT From: Wen Yang We occasionally hit a lockdep "Invalid wait context" warning in production when a reactor callback is preempted by a timer interrupt. On interrupt exit the scheduler takes rq->__lock (LD_WAIT_SPIN) while rv_react() still holds its wait-type-override map, which declared LD_WAIT_FREE. On any kernel where the task context has preemption enabled (not just CONFIG_PREEMPT_RT) this triggers a spurious lockdep report: [ BUG: Invalid wait context ] 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} Changes in v3: Patch 1: - Rewrite commit message to clarify that the bug is not PREEMPT_RT-specific: any preemptible task context can be interrupted by a timer, and the scheduler acquires rq->__lock (LD_WAIT_SPIN) on interrupt exit while rv_react() still holds its LD_WAIT_FREE override map. - Rewrite the inline comment in rv_react() to make clear. Patch 3: - Fix commit message: missing EXPORT_SYMBOL_GPL() is caught by modpost at link time, not at load time. Patch 4: - Drop test_reactor_registered bool and the unregister_test_reactor() wrapper entirely. - Remove test_register_unregister(); the teardown already covers the unregister path, and test_double_register() exercises the full register->verify->unregister-via-teardown flow. - Replace the runtime KUNIT_ASSERT_EQ(strlen(...)) guard in test_name_too_long() with a _Static_assert on the name array size. - In test_react_no_callback(): reuse the existing react_call_count atomic to assert that the callback was never invoked. This catches a broader class of regressions — e.g. an inverted or missing NULL guard that does not cause a NULL dereference. No functional change to patches 2-3; the series structure is unchanged. Tested with CONFIG_PROVE_LOCKING=y and CONFIG_KUNIT=y. v2: https://lore.kernel.org/lkml/cover.1785695669.git.wen.yang@linux.dev/ v1: https://lore.kernel.org/lkml/cover.1781541556.git.wen.yang@linux.dev/ Wen Yang (4): rv/reactors: use context-sensitive lockdep wait type in rv_react() rv/reactors: propagate rv_register_reactor() error from reactor init rv/reactors: export rv_register_reactor() and rv_unregister_reactor() rv/reactors: add KUnit tests for reactor registration and dispatch kernel/trace/rv/Kconfig | 12 +++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/reactor_panic.c | 3 +- kernel/trace/rv/reactor_printk.c | 3 +- kernel/trace/rv/rv_reactors.c | 22 +++-- kernel/trace/rv/rv_reactors_kunit.c | 119 ++++++++++++++++++++++++++++ 6 files changed, 151 insertions(+), 9 deletions(-) create mode 100644 kernel/trace/rv/rv_reactors_kunit.c base-commit: 785095112f4198de49760552374f364043c8dbdf -- 2.25.1