From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=193.142.43.55 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793796404; b=3dnByGgEmZ0uuN92PhTLiKmK/GAscdrXd3VCiid+KUJd3az5d1dAk0VfQHS/4EtxgW3J qSNHCSLY3u6DAURQmfyRiG5xeiZn1AVxf8v41CcxXCKKrm/yaMXiDXJl9rgtPdwi7qzyS 08QxcboHxq84k+N54LRIjC/tJnSTeNbiPXQ0cvZBd4S8Pr2CTO4iXya1jOJ3dpGQTir/n +7tt6vnyn1f9tlzdtTSAeeU4XloKyQSdsTu8vSMYcIbsT6JTmxVbPMj8sTAEtVfgw1wIP mdsnPiocZI2hSDhfebjyi82Lb8F+EAqeMoOQ7GDCYv6OexDy0kd6b97Abovwahc2Fug== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793796404; h=DMARC-Filter:From:DKIM-Signature:DKIM-Signature:To:Cc:Subject: In-Reply-To:References:Date:Message-ID:MIME-Version:Content-Type; bh=eyikFY7C3QT90Wffq51wylQVXUvJEQUhu4OAz+HFx3o=; b=R+1//Tvu0CLQATT5Jn0lP+V+H/stPs7lU7beirUIRH3cdsqjY7yJRgU/4vhgN55uMH2X wOyHD2faE5Pafc3xoKkZyicmQIiF+CVKN/Zd2pq7dqCek0XQ/41DcGbzS1tY1eToJ5JrK 7vpaZgfQVfDr3xNS/qGUc8y4OydkAxm8xiT1+pSIoD4Q2r+NyRj7CPAnpIbx3fPVG14y9 PaWiJ7+I/4/dbHOrrAeQ3vD9atXOcYg4Lq2Xr87Dtxo79+bmZKY3fsA3q+JE2DkzHdSVX Mvdbd6dOtPdWGpSsFYq3PJOrLksS1bmaxxOrvHXYebOsMYml6K6lQh3LqPuyg6LADtA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=zdBtH5ob; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=wIQ63DUR; arc=none smtp.remote-ip=193.142.43.55 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3ADBF606A31B for ; Wed, 4 Nov 2026 12:46:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 3ADBF606A31B Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=zdBtH5ob; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=wIQ63DUR From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1793796402; 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: in-reply-to:in-reply-to:references:references; bh=eyikFY7C3QT90Wffq51wylQVXUvJEQUhu4OAz+HFx3o=; b=zdBtH5obaDFfrIctvpeUqRTTkgwPxfazmbskLSgltT/A94ZZ1K8Ppk4tSyDeXlLq8Wx2k1 xm9ByBkUCxUiom+fr+IVp02kRd5m6iu2qU829IjaMp2QyPLlJieJAM7mzSIuKtXcDYoPfN sLevhww+VRm2riDO01iSzzMS8K2KfcD2EbaQWERirQnKh2J+JJQNVc8kuQO/Ga3fMzomUo JbnyD7Jj9NZf9uk1Yt89g7NO3leHPmsT7/6BCH2qd8l2LhB6XR7IQFObQ8IGCLU1DiJZdy 0EmxvLSN+t6QBD80CxIRbkyiunmehDMsBX/1Fq5VxVh7oG7FRQ7g4TMvaIy2nw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1793796402; 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: in-reply-to:in-reply-to:references:references; bh=eyikFY7C3QT90Wffq51wylQVXUvJEQUhu4OAz+HFx3o=; b=wIQ63DURVvopOx1dWx+LtaFunvLP89idAslCHEliWa9o2uFPZnpxOZ3jh7s7PD9Za+/h2r BFZaL97Vc/yVlOCg== To: Breno Leitao , Marco Elver , Petr Mladek Cc: Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Dmitry Vyukov , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, kernel-team@meta.com, Breno Leitao Subject: Re: [PATCH v2] kcsan: Don't enter an nbcon emergency section for verbose reports In-Reply-To: <20261104-kcsan-irqtrace-emergency-v2-1-ceafc0098a25@debian.org> References: <20261104-kcsan-irqtrace-emergency-v2-1-ceafc0098a25@debian.org> Date: Wed, 04 Nov 2026 13:52:41 +0106 Message-ID: <87v76cahn2.fsf@jogness.linutronix.de> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain On 2026-11-04, Breno Leitao wrote: > Since commit 59cd94ef8009 ("lockdep: Mark emergency sections in lockdep > splats"), print_irqtrace_events() runs inside an nbcon emergency > section. It is not only used by lockdep splats, though: verbose KCSAN > reports call it too, and a data race report is not an emergency. Yet in > an emergency section, every printk() flushes all pending records to the > nbcon consoles from the calling context, instead of leaving them to the > printk threads. Wouldn't the below diff be the proper fix? John diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index c3dc84a7cef26..71f1b4b8f06d5 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -4245,8 +4245,6 @@ void print_irqtrace_events(struct task_struct *curr) { const struct irqtrace_events *trace = &curr->irqtrace; - nbcon_cpu_emergency_enter(); - printk("irq event stamp: %u\n", trace->irq_events); printk("hardirqs last enabled at (%u): [<%px>] %pS\n", trace->hardirq_enable_event, (void *)trace->hardirq_enable_ip, @@ -4260,8 +4258,6 @@ void print_irqtrace_events(struct task_struct *curr) printk("softirqs last disabled at (%u): [<%px>] %pS\n", trace->softirq_disable_event, (void *)trace->softirq_disable_ip, (void *)trace->softirq_disable_ip); - - nbcon_cpu_emergency_exit(); } static int HARDIRQ_verbose(struct lock_class *class) @@ -5797,8 +5793,11 @@ static noinstr void check_flags(unsigned long flags) } #endif - if (!debug_locks) + if (!debug_locks) { + nbcon_cpu_emergency_enter(); print_irqtrace_events(current); + nbcon_cpu_emergency_exit(); + } instrumentation_end(); #endif