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 C37172750E6; Thu, 16 Apr 2026 10:48:21 +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=1776336503; cv=none; b=qP5n7jjwZQ1iG2nvRIcPhjBqTulJLoapcHJMdjIBbLTGq6+G+A9m0tjX7Ni/DBSK9EUvg3PMKPbo3FdZHIpBlViZBAmaIZrYfSmjp91M+GWTCDPeS75tjNPAp/mhiLrG5lTKoerwBvFgbT4GPBakmo7NMRc0MtNi7CIIZkVE0fc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776336503; c=relaxed/simple; bh=FJAjF3c/YQAZ4eKmPCcFLz5owz9LmueVbVqgFhgoVpA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Zb6AqB0/Jq6RXqHE78qISulFtcJeJ3kho++TQDq+/uTXOdxXd6p2gOXVYwPlARiU+waOtcSxKTHnD6AT6igu6e2v6iT9BJgyGBMHJNi0JM8KcxyaO3wEsKs2Nk19keLp3NxVAEd45axr8eMdKMUeKLwDsPVawWowr93pAWnFrgQ= 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=M7tsHkFG; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=8GjlmBf+; 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="M7tsHkFG"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="8GjlmBf+" Date: Thu, 16 Apr 2026 12:48:18 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1776336499; 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=I3a7Sj+pE8WYMPoTgZHgFbXHwJPGyl/mbNxCrht2ciU=; b=M7tsHkFGF/XC8bt3idRz80P1SxzXCGO5gMiIWSHRK8LMVMmjP8P+3kTMmXxtO7N+rHVujO /9lPKTFh5pnHLY3aZo0FnLakIWA8NLCmwe208rHOmbAIZCHT8A2M78ZTTB0Z1fmbfxpzBZ KXKhIuoxSi7O4AHAJgOI0frsk5ZD457tJbJorusOKU+FYTrbdTlOH8tgKjXmA+3yNt2vva yIT//0jnfMNrYs/APwx5hyHpBbiXD2QSwVayAYMHh7YKRWlPYSkfpHcb9Lq46GuMAydJV3 3Gnzs4x910dtN0uQFajj73frA9acmQ7Xr3L+kNwKifwZ8AEWCVhkxbEyNSe/dA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1776336499; 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=I3a7Sj+pE8WYMPoTgZHgFbXHwJPGyl/mbNxCrht2ciU=; b=8GjlmBf+HMAGSVLkjIzbXCrFa42WdQ00ZsKu1/uWFYxmusGD/wcUQkNpsq+VB0rLr3aovX GqiFZulv+LsAkvAw== From: Sebastian Andrzej Siewior To: Marek Vasut Cc: netdev@vger.kernel.org, stable@vger.kernel.org, "David S. Miller" , Andrew Lunn , Eric Dumazet , Jakub Kicinski , Nicolai Buchwitz , Paolo Abeni , Ronald Wahl , Yicong Hui , linux-kernel@vger.kernel.org Subject: Re: [net,PATCH v3 1/2] net: ks8851: Reinstate disabling of BHs around IRQ handler Message-ID: <20260416104818._EDbo9hA@linutronix.de> References: <20260414103327.113500-1-marex@nabladev.com> <20260414125753.Im6GAIHn@linutronix.de> <2fcfb84f-69f6-493e-94d6-95d85d8000f6@nabladev.com> <20260414145218.lsNpdAJI@linutronix.de> <7734527a-d08b-49fa-b258-c37c5ae2da55@nabladev.com> <20260416062159.fPxqc52X@linutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On 2026-04-16 11:26:00 [+0200], Marek Vasut wrote: > > memory allocation. Therefore I am saying this backtrace is from an older > > kernel. > > I actually did update the backtrace in V3 with the one from next 20260413 > that contained b44596ffe1b4 ("ARM: Allow to enable RT") from > stable-rt/v6.12-rt-rebase branch [1] . > > I think I misunderstood the usage of "softirq is raised" vs. "softirq is > invoked" above . Is it possible that there was an already raised softirq > before the threaded IRQ handler was invoked, and __netdev_alloc_skb() is > what invoked that softirq ? It is not impossible. Something needs to netif_wake_queue() and ks8851_irq() must only report IRQ_RXI (not IRQ_TXI). Then it can happen. But usually the driver "stops" the queue if it can't process any new packets and resumes it once a packet has been sent so it has room again. > > If there is a flaw in my the theory please explain _how_ you managed > > that get that backtrace. I am sure it must have from an older kernel and > > _now_ this lockup also happens on !RT kernels (except for the SPI > > platform). > I used [1] , with PREEMPT_RT enabled , on stm32mp157c SoC . I ran iperf3 -s > on the stm32 side, iperf3 -c 192.168.1.2 -t 0 --bidir on the hostpc side. > The backtrace happened shortly after. Hmm. Let me accept it then. Sebastian