From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C73362D6E59 for ; Tue, 12 Aug 2025 10:17:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754993827; cv=none; b=dndxYa1Kqto1QWzCdTv03m85+BtrFuvFjHKpnlmUPjdb+iDfCoHvtgLcvxWHRSDH8vOzXQ4OQAUuwbupRAHP69D/UGG+AGuVxSvcMJHsmj+F2HiO5aRme0XvHpjiZt+aVv2gY2qPJM8ox2BZvhoATMhSqVGT3fzsDNtTrrKYLrI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754993827; c=relaxed/simple; bh=/O7rQIW2crUsCtHM7R5MYL0IYB1Ko7dTRUfLAxpT1Ak=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=PwIO5a7KZpBWjQY3jUporWyK7FhHbTNKbm//Ibrv1ppDr4t59R63hB+f9jXwCoxbTZuInK2x+pjRuJgM7TxMjHRmopBVX+n2+JOWMlTGpEE82wxVF7GT27fre+iFfql2NYrH5rMSEG2oq5N+/cQxLHEc2niu+lrMk0LxcNu5OLo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EuNGn3Wb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EuNGn3Wb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63B44C4CEF0; Tue, 12 Aug 2025 10:17:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754993827; bh=/O7rQIW2crUsCtHM7R5MYL0IYB1Ko7dTRUfLAxpT1Ak=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=EuNGn3WbJ+cZLh1cdoV61+KvZl6Gbnv8g8dDrPOaXkE8Xbm7a/PlkR+XMJcOMoUuT Zizv34H/KNxpthZWixJSJPOg+RyAmGkUMBkcHFzbGc4BHlbxRC1XjXiYHkho5gK0Wi GGgTUGbDQ0vgKs3KXc8gjIY+OOSkl39T80clL092GeWC2gGLrd9AB1IWLPNGZI+sTr wbBzDe06txRb3HdzlnTM4Iyr7yjBJZV0V9zNc2yXwGaxTElCev/9vkqJQLhj8+j9bD re2rnElAywi+nV5P+dbWqpw4dlfijpN5jY5y/VqNqU7n1QYTWwOtE3AyHi16+N9Qq8 KPs8WNo6vFDKg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1ulm41-006cns-BF; Tue, 12 Aug 2025 11:17:05 +0100 Date: Tue, 12 Aug 2025 11:17:04 +0100 Message-ID: <86ms84974v.wl-maz@kernel.org> From: Marc Zyngier To: Coiby Xu Cc: Thomas Gleixner , linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [Regression] kdump fails to get DHCP address unless booting with pci=nomsi or without nr_cpus=1 In-Reply-To: References: <87bjom8106.ffs@tglx> <878qjq80yu.ffs@tglx> <86v7mt9ai3.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: coxu@redhat.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, kexec@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 12 Aug 2025 11:09:12 +0100, Coiby Xu wrote: > > On Mon, Aug 11, 2025 at 03:52:04PM +0100, Marc Zyngier wrote: > > On Mon, 11 Aug 2025 14:03:21 +0100, > > Thomas Gleixner wrote: > >> > >> On Mon, Aug 11 2025 at 15:02, Thomas Gleixner wrote: > >> > >> CC+ Marc > >> > >> > On Mon, Aug 11 2025 at 11:23, Coiby Xu wrote: > >> >> Recently I met an issue that on certain virtual machines, the kdump > >> >> kernel fails to get DHCP IP address most of times starting from > >> >> 6.11-rc2. git bisection shows commit b5712bf89b4b ("irqchip/gic-v3-its: > >> >> Provide MSI parent for PCI/MSI[-X]") is the 1st bad commit, > >> >> > >> >> # good: [7d189c77106ed6df09829f7a419e35ada67b2bd0] PCI/MSI: Provide > >> >> # MSI_FLAG_PCI_MSI_MASK_PARENT > >> >> git bisect good 7d189c77106ed6df09829f7a419e35ada67b2bd0 > >> >> # good: [48f71d56e2b87839052d2a2ec32fc97a79c3e264] irqchip/gic-v3-its: > >> >> # Provide MSI parent infrastructure > >> >> git bisect good 48f71d56e2b87839052d2a2ec32fc97a79c3e264 > >> >> # good: [8c41ccec839c622b2d1be769a95405e4e9a4cb20] irqchip/irq-msi-lib: > >> >> # Prepare for PCI MSI/MSIX > >> >> git bisect good 8c41ccec839c622b2d1be769a95405e4e9a4cb20 > >> >> # first bad commit: [b5712bf89b4bbc5bcc9ebde8753ad222f1f68296] > >> >> # irqchip/gic-v3-its: Provide MSI parent for PCI/MSI[-X] > >> > > >> > There were follow up fixes on this, so isolating this one is not really > >> > conclusive. > >> > > >> > Is the problem still there on v6.16 and v6.17-rc1? > > > > Yeah, there are way too many things that have been addressed since. > > kdump is also a particularly nasty case, as it tends to rely on the > > redistributor tables programmed by the previous kernel. > > Thanks for providing a clue. This may also explain explain why I fails > to reproduce this issue against 1st kernel even with the same cmdline of > the kdump kernel. I'm not sure that's a clue. It's only an indication that things are not necessarily easy to spot. Has it ever been reproduced on bare metal? Have you tried v6.16 as instructed? > > > > > Also, this says "virtual machines". What's the hypervisor? > > I'll contact the lab administrator. What kinds of info I should collect > to help you narrow down the issue? Surely you know what hypervisor you're running on, right? > > > How hard is it to reproduce? > > It can be reproduced reliably on certain machines. But as of writing I > haven't reproduced it on other KVM virtual machines on three different > host machines. Which machines? I'm sorry, but if you want help on this, you'll have to provide actual information. Thanks, M. -- Without deviation from the norm, progress is not possible.