From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 81CF82C21DF; Thu, 13 Nov 2025 17:07:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763053623; cv=none; b=jYaRHO6SkSXnbBw8OlSF2svxAxBCKr9Z4UBbaA3hKYY3hPfxsa3VaRBmEI6hExl/HncuDH32PfFim4volkQOD62xgH1Cj/BdSGj44DnK32QHlxv4lnhT4hoWy2uReLke4Dn5vGagwlNnpzQ+TPf6wPkji6kdMw+mxGCU62F8oV0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763053623; c=relaxed/simple; bh=9dAaIOs3rAYPxGHSfIiOz3cQ+9IFBZ5qeehTd/g/Nu8=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=aEomJWESWapQGK/e+7H4aAMnQ4nmQOZEIkTT3KjJnmkwAwRn50P9852W1bXe9/5vLHnMXDQCLdwCjrlXyTD9FdjYjOOHOUaBgrihnm2JShiT19QLglaKTzyUZDcp3ACi2G23402n52ulgRMQtjgLsoFvcJWd+n+nLtaZy8J2lyo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=JVN/txP2; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=OEthngAY; arc=none smtp.client-ip=193.142.43.55 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) header.d=linutronix.de header.i=@linutronix.de header.b="JVN/txP2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="OEthngAY" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1763053618; 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=T+nGnj7ZMz7mfV8MZgv8GRt6v8MVSGMnzy3RM2g4/2k=; b=JVN/txP2lVqxPSnDFNKVnZmX9SYMbgjUVG2H/ffOPpcQWrAh+UeTUZM37kagPNCWNZVmWR 3tRef1eol4YSPXIHwEol2ipJbh+Xg42B4WbVoXlnqRuY0mrQ1MGq71k0pIptRIhvPMXGhD Vu8KqaTGFPX4UoUZAfLisk++h2yUXA/MEvg2Znq1PpF/7U6WA4gEox5kHmc4NJHN6W4EQq O5Deapou6qc9vRATpR8vcTlLYNS/kTaNeJTNdP+AbMddqnIY1H+NzBK0ow0xl5IpaaWNBy nE4vM4up4lGOjjPt0VyKRYqU/3TdVCK1lLBx3IJGHKIrPpizDlu+CvfM0c7rsg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1763053618; 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=T+nGnj7ZMz7mfV8MZgv8GRt6v8MVSGMnzy3RM2g4/2k=; b=OEthngAYRUpCcUNQvf3H4PcDV5DuOVrCrZvvU9+kPpTbKmVSQf2xLMrV4pnpkRSlop7ol4 0zbSPXn3QEwGAUDw== To: debarbos@redhat.com Cc: Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Sherry Sun , Jacky Bai , Jon Hunter , Thierry Reding , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH printk v2 2/2] printk: Avoid scheduling irq_work on suspend In-Reply-To: References: <20251113160351.113031-1-john.ogness@linutronix.de> <20251113160351.113031-3-john.ogness@linutronix.de> Date: Thu, 13 Nov 2025 18:12:57 +0106 Message-ID: <874iqxlv4e.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Hi Derek, On 2025-11-13, Derek Barbosa wrote: > Thanks for this. I have recently have been seeing the same issue with a large-CPU > workstation system in which the serial console been locking up entry/exit of S4 > Hibernation sleep state at different intervals. > > I am still running tests on the V1 of the series to determine reproducibility, > but I will try to get this version tested in a timely manner as well. > > I did, however, test the proto-patch at [0]. The original issue was reproducible > with this patch applied. Avoiding klogd waking in vprintk_emit() and the > addition of the check in nbcon.c (new in this series) opposed to aborting > callers outright seems more airtight. I assume the problem you are seeing is with the PREEMPT_RT patches applied (i.e. with the 8250-NBCON included). If that is the case, note that recent versions of the 8250 driver introduce its own irq_work that is also problematic. I am currently reworking the 8250-NBCON series so that it does not introduce irq_work. Since you probably are not doing anything related to modem control, maybe you could test with the following hack (assuming you are using a v6.14 or later PREEMPT_RT patched kernel). diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 96d32db9f8872..2ad0f91ad467a 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -3459,7 +3459,7 @@ void serial8250_console_write(struct uart_8250_port *up, * may be a context that does not permit waking up tasks. */ if (is_atomic) - irq_work_queue(&up->modem_status_work); + ;//irq_work_queue(&up->modem_status_work); else serial8250_modem_status(up); } > [0] https://github.com/Linutronix/linux/commit/ae173249d9028ef159fba040bdab260d80dda43f John