From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-173.mta1.migadu.com (out-173.mta1.migadu.com [95.215.58.173]) (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 ED2CA22D4F6 for ; Thu, 28 Aug 2025 14:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756393074; cv=none; b=TxGjKlvQ52v/iSItMbLPfzwXI87rYsIsJeIw+9BEe1lPIVarBi6Nmsu+ivfeN1cMxJRzm0QlpnSmRFEXeAp9dojAHwF9g8Pemx6P1rV0WHFIqy9lPvsNXwdk6c15B9L8Uwe16QT29bjGVu94T3kWBwThQUwuCAtg+8E3WSmnTB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756393074; c=relaxed/simple; bh=/piA/tAynLslqC3CI5eA5S97oqvJFuIUWdyDi0O7ez8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tBTWvnX0NlUawQCzwjh9sPHo+BpPzsgTBYy8PtHUjtnEZUajOZnoggTYpnv8dbEsPvxNqACTq6rSIAweEctGWmOyVtxj/l+xxo26Cgyk6TVtSLVfZeiAJMOJrU9C6xUGIWUg483ABWhn+VWroXcugfpgwOoRMRKJ3oXsvNic3Bg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=IjAYaN6p; arc=none smtp.client-ip=95.215.58.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="IjAYaN6p" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756393071; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=r2OlzHNvPNbmcUFVqgSbczvsRH//BtNhcm7pgGO6xi8=; b=IjAYaN6pjGv8XZdchjBQ6pLDHxL77XCMmfZZEHWwvYJRmLCMM1LG6DslFjRE/bcTalb7eF Le2I5gHHR9q2U2qBUT4Plmmpyut7cDFxm6ZL6mJYzDoQUWWmQgycWAivy8FMnGZCuDda+A coXWnK/YGJx//si0q1idP3EICl7mKfU= Date: Thu, 28 Aug 2025 10:57:42 -0400 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: netpoll: raspberrypi [4 5] driver locking woes To: Mike Galbraith , Robert Hancock Cc: Breno Leitao , "netdev@vger.kernel.org" References: <4698029bbe7d7a33edd905a027e3a183ac51ad8a.camel@gmx.de> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Sean Anderson In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Hi Mike, On 8/27/25 12:02, Mike Galbraith wrote: > Unexpected addendum to done deal datapoint, so off list. > > On Tue, 2025-08-26 at 11:49 +0200, Mike Galbraith wrote: >> >> The pi5 gripe fix is equally trivial, but submitting that is pointless >> given there's something else amiss in fingered commit. This is all of >> the crash info that escapes the box w/wo gripes silenced. >> >> [ 51.688868] sysrq: Trigger a crash >> [ 51.688892] Kernel panic - not syncing: sysrq triggered crash >> [ 51.698066] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.17.0-rc2-v8-lockdep #533 PREEMPTLAZY >> [ 51.707234] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT) >> [ 51.713085] Call trace: >> [ 51.715532] show_stack+0x20/0x38 (C) >> [ 51.719206] dump_stack_lvl+0x38/0xd0 >> [ 51.722878] dump_stack+0x18/0x28 >> >> That aspect is a punt and run atm (time.. and dash of laziness:). > > Plan was to end datapoint thread, but after booting pi5's 6.12 kernel, > for some reason I fired up netconsole.. and box promptly exhibited the > netpoll locking bug warning, indicating presence of 138badbc21a0. > Instead of saying to self "nope, just walk away", I poked SysRq-C.. and > the bloody damn monitoring box received a 100% complete death rattle. > Well bugger. Did you get a backtrace for this? And to be clear, the steps to reproduce this are to boot a kernel with lockdep enabled with netconsole on macb and then hit sysrq? > Two trees contain locking buglet introducing 138badbc21a0, 6.12.41 and > 6.17.0, but only the later reproduces the above mess. A quick stare at > git diff inspired checking e6a532185daa, and sure enough reverting only > it reproduced a functional netconsole, modulo warnings, ie the mess > above manifests only with BOTH resident. Either revert 138badbc21a0, > or revert e6a532185daa and fix the 138badbc21a0 locking buglet, and the > result is the same, a perfectly functional warning free netconsole.