From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0595A39E19A for ; Wed, 17 Jun 2026 11:59:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781697573; cv=none; b=lVRQWjWBfI4rCSo6otYWz6ECPJh10M+KdzOoefvnS5Hn5qxG044VcCMLuvntvLsc0abpaXbKK/NJl5PjHJbJGw0mfg2SlZlka0I9HEgEgr4oF3SLZ4SnBA99rtjZkUWzzyeVwH6B18DW2GhFTHUlUD//bEQdkneepoWZDr/zh18= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781697573; c=relaxed/simple; bh=cvsxccTzFVOpMQezm4HlOWz2aB8KWwD6zxOBa9D3eA8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Hj4cFemLqcy2NUNESfazY5BbcMMbThF/5+S4ZbwfUN5DTcQ/CpGxmjticveGn9dEWBBUtIQVBzcvbElAeoOpNpssxQOaVGB/giR+Zenf0cgrMjEB2oHC4TYydr/EEnkR7nYKeRQ8k+g1aAnLPpDbFgEjxJBYwbu6ewjSCsBqi1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=M6qD7bvt; arc=none smtp.client-ip=209.85.128.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="M6qD7bvt" Received: by mail-wm1-f45.google.com with SMTP id 5b1f17b1804b1-490b8ac62baso8542395e9.0 for ; Wed, 17 Jun 2026 04:59:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1781697570; x=1782302370; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=wFy1siI5GPA02P4SigwJOvEY2/GCKPj1mDQV6Az/rvE=; b=M6qD7bvtZL4WoGDeCzK3htwiEAuyM4CktDeM5fxxmuqw8gryeGiBqYiMqXeDX0TObt ZhwgjWODAUq1Wf3Ii+fDS6wIbRIKznp+VbtnNcMlXDPeRTSb35z7nADRBqaaQQJpu7c5 E+wQDUsA8ekgkOZFpVB+TO4QInOdJdP0boeMLaa7Jm+N+CRknJN8WskaFdqdSBs19MsJ eGKWMVRPZzLWCQU6WqgGC1mSSdRD/AcSd5UzNGZKVBVNC6xyNW6sQLx4BqpiZ+xh4bnR kH561LSvnpzCGzIWt+h44lsPyKA5JUitnlXOYfdn+0QaRB9CPyOj+PXMEt90lJWu8pBR H3GA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781697570; x=1782302370; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=wFy1siI5GPA02P4SigwJOvEY2/GCKPj1mDQV6Az/rvE=; b=SDu06JaDcrpPS9kVyQ4Q5SvrdyTUbogETxjCiflrYKJ7TCO38pt0PFrTqm4tElfHRX AkncAAGimr+HfM3KLYnhS+/Fq0otKoxg/75uYhmlXxVqvrqnPwRvWvZLKJHOECBFvmeg gNzuyME2tP7AvXlBx3LCj3G1qmstzhwm5airuoQhwr9xBUnKxe0yW6pAt1yaNdmCWl9G IaBSveuR/5xCqGaFRmi5peJs80UZ/Zezm40Wzvln1zfqn+AzKu5PvLqnwMKtXEiY2wsb GXCg5ULgFDDkT2n0EZBOyN99r3NZAa8tO5mnS9FrfNPruEYEy0AXfC8iLKt9P3FbfZZL wufA== X-Forwarded-Encrypted: i=1; AFNElJ9EPH67j/bDaFO1Nnx0jxpKoMpAb+PEc1/wPK4DyUxsymrdOB1jLuVf2UV4RBVVub2UP4sMbGo=@vger.kernel.org X-Gm-Message-State: AOJu0YxmAreu58TTTAUSGMNPxPTt7unHHWbdKtCE6xuAY7WuZSIRu+gI lJLbC66VBPJ4/fNTuSJqaeItJJy9sBoIKs3o5aIq7aO7DB7HUIG3aO0knAOpNcDt4veh0J84OYv fXSBe X-Gm-Gg: Acq92OFj7IwUIL8P+u3NCVBLl7xUO5M83m1Vw6rh0Gpoo9l1rVIageI7q3GkIqnn1z2 xB0YTZBpum89Q8ko4PAF0XvNp2PR0JuUdxcYAfhWm1mTY3tHV3g1G7wzDnFKuuY3NhMTi3Ss5OM cFSoozbc4jfwShE5dh/FhkWpFN+VNQEzMzXUUpaTiKOxOyS5u7xswnhFgZu/sJKjL0uiQs5bsEX 3pYTTDkYYNAIy6LCa6U7qlyDcdIW3Y6+hqK0OIRDtA9RX52S2+tNtK5Rmas0yz9FiXiXa3SqC20 wcvUgEH49uZnkuH1TYLmz4P8r8bXTMfKb0k/Kf9ITVHrpvQVnu850Yemf0HpaSl/xU1to/gyabc oNluV5oLqXE9YDJT1MouwkGvwBNF/EiZhQasEL7E1e5Ee6+mn0xOItd7Xh2Yq3at3VhlNDkpTpn xkvX7PqDyYnEu2jCc= X-Received: by 2002:a05:600d:8450:10b0:490:4035:323 with SMTP id 5b1f17b1804b1-492340e75cdmr33496715e9.9.1781697570289; Wed, 17 Jun 2026 04:59:30 -0700 (PDT) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4606f26f309sm48879291f8f.14.2026.06.17.04.59.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jun 2026 04:59:29 -0700 (PDT) Date: Wed, 17 Jun 2026 13:59:27 +0200 From: Petr Mladek To: Peter Zijlstra Cc: Sebastian Andrzej Siewior , Jakub Kicinski , John Ogness , Sergey Senozhatsky , Vlad Poenaru , Thomas Gleixner , netdev@vger.kernel.org, "David S . Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Breno Leitao , Clark Williams , Steven Rostedt , linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Frederic Weisbecker , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , K Prateek Nayak Subject: Re: [PATCH net] netpoll: run NAPI poll in softirq context to avoid rq->lock self-deadlock Message-ID: References: <20260610183621.3915271-1-vlad.wing@gmail.com> <20260611191114.5bc43a59@kernel.org> <20260616103529.Yh9Dxsjp@linutronix.de> <20260616081128.04e2c8dd@kernel.org> <20260616153122.keHMKvVT@linutronix.de> <20260617111504.GK49951@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260617111504.GK49951@noisy.programming.kicks-ass.net> On Wed 2026-06-17 13:15:04, Peter Zijlstra wrote: > On Wed, Jun 17, 2026 at 12:12:07PM +0200, Petr Mladek wrote: > > On Tue 2026-06-16 17:31:22, Sebastian Andrzej Siewior wrote: > > > On 2026-06-16 08:11:28 [-0700], Jakub Kicinski wrote: > > > > > > > > > > Adding sched and printk folks for opinions while eyeballing > > > > > WARN_ON_DEFERRED(). > > > > > > > > Thanks a lot for looking into this! To be clear - the printk_deferred / > > > > WARN_DEFERRED would be just for stable? Or there's still some > > > > sensitivity even with nbcon? > > > > > > We already have printk_deferred(). WARN_DEFERRED() would be new. I > > > *think* this is not limited netpoll/ netconsole but all console drivers > > > not using CON_NBCON if the printk (via WARN) occurs with the rq held. > > > I don't remember all the details but printk_deferred() was introduced to > > > circumvent this until printk is fixed. > > > > Just to make it clear. The problem with the legacy consoles is that > > they are called under console_lock() which is a semaphore. And it > > calls wake_up_process() in console_unlock() when there is another > > waiter on the lock. > > > > > Once we get rid of those legacy drivers and NBCON is the default we can > > > get rid of printk_deferred() :) > > > > Yup. > > Can't we push all the legacy consoles into a single legacy kthread? I > mean, converting all consoles is of course awesome, but should we really > wait for that? I am afraid that converting the consoles one by one is the deal with Linus. I could imagine to moving last few sinners into the kthread when the majority is converted. But we are far from there :-/ Best Regards, Petr