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=1793803335; b=X8SWm00hj7go3FrRP05ESTMWa2XC7AaalInQlrJo/PeaND5yEI/b60/7Q6qHoUm6IjSg 2ngiE1G5KekZTeardj6QjEmugtTf5OMTt4o7hR6NBIdDyAaC5BEJYw/7RQwslnEfeIdA3 0kd8Uhp32sp6LaXKLm89hvvZbkSLM6VBDPTFRmpV/1NczJokToi16yLMNKSLh7sxOn8hw aZlWEwh/biOnl0BLgScEj6ezFX+o8icqmEZUJh+lI/E5TM3HLUoip5kfHbNTRKZ2HvfI8 1QcEvrRQc1uBAWR50k0wCJuLVqj3ptYKER9+ZHPYfxwuDYjWpX1Vod47eTQ4a6SFtPQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793803335; h=DMARC-Filter:From:DKIM-Signature:DKIM-Signature:To:Cc:Subject: In-Reply-To:References:Date:Message-ID:MIME-Version:Content-Type; bh=Fl1gbLhBQfxuB0Za0lmrQManNOX8Zck/p2HtBIvRL8s=; b=ZlUhPsTcSOWbqh56rcikHhar/IRy6D4v2RiOlCzvxQZgK7TXBp+Do+YICXFGz/fgPnka Rw7N8a3NmruW3jxyP9W4YoD28LRSHa6esxasMjYsXPjKhJQJpcjTBQf9++YBxuQu9U58e S5rt6mBY6aIj/7UEQ+0DimAMgg4/Gu7+Zr3PUtWtQ+2RSWkvOuw98IziS8P2jb1K1C4oz Sq7hEYWOzco3x84BkDwUlsyQoaaomfDzZOjflcS0v4qga3HCsEyoVJLI6SBaqrlpOHH5K RdPQ7NMguUWV4W3tdJI+o9/F4DyraSVNrBsj/MTKNtVHl2Uhsru9532kVKNtXsbsQOg== 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=3OXSg5DX; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=8sSG0Qq2; 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 A9713606A328 for ; Wed, 4 Nov 2026 14:42:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A9713606A328 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=3OXSg5DX; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=8sSG0Qq2 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1793803326; 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=Fl1gbLhBQfxuB0Za0lmrQManNOX8Zck/p2HtBIvRL8s=; b=3OXSg5DXF+Q8bYnZn4ubic7S382+ZMoVMVKjLabNvLANRBMaClCf76C85U7esjEf5noumQ NHzkVwiKxfd87KwNQYeMnrJ8QAG56nQivOJ+Brv/GugNaQ4RI9kPzPhuFUHIkqRK546KbD GKXA+iYcnFRHaIxPFJZJ8sMF/t1MMYXn4vD6IdWbqM5xF8vxqIvlyWm3IcUMfMubppDUid b7S8OrAcRL2Ee7ZBEL9JJITQqv//8uoSp4Q25phkyMe0NMOd4d3JZGGQOTssx0ZQyegt6f rNpkpTk010jAX9wVIH3wdjffkmztTI2Ebp+yDGOGe+ZLnCjki9vvfTEUxRQImA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1793803326; 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=Fl1gbLhBQfxuB0Za0lmrQManNOX8Zck/p2HtBIvRL8s=; b=8sSG0Qq2MI4SgahfhyqkbYBy9/x20pnevwNV+nKRQ8DinEJYgdSsYlGGkHPriFvP+l9Qmo ByUPZnKBCtVW/IBQ== To: Breno Leitao Cc: Marco Elver , Petr Mladek , 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 Subject: Re: [PATCH v2] kcsan: Don't enter an nbcon emergency section for verbose reports In-Reply-To: References: <20261104-kcsan-irqtrace-emergency-v2-1-ceafc0098a25@debian.org> <87v76cahn2.fsf@jogness.linutronix.de> Date: Wed, 04 Nov 2026 15:48:06 +0106 Message-ID: <871p90psjl.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: >> 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 > > Yes, but it was unclear to me what were the invocations of > print_irqtrace_events() that needed the emergency turned on. > > how did you decided that only check_flags() needed it? The emergency enter/exit's are intended for lockdep splats. AFAICT check_flags() was the only call to print_irqtrace_events() that was not already in emergency state for lockdep splats. KCSAN is not the only non-lockdep caller of print_irqtrace_events(). So my suggested fix applies to the other non-lockdep users as well. Commit 59cd94ef8009 ("lockdep: Mark emergency sections in lockdep splats") was only intended for lockdep splats. John