From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57A27C433DF for ; Tue, 18 Aug 2020 00:54:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10D752078D for ; Tue, 18 Aug 2020 00:54:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597712094; bh=VD62CXPwCkmJuAeTqgY5XHb25Dy+4IXcXfQdlHKK0QQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=oq4uiSEqh5qW0x0b7wVigM91ryzgBFwrw98S9OEeqaRa1/W42HJ9aXKNmtV8BZaCO 2KxzBU63lm9rrl56NDQoyaBxjToIoR4+fbcA0b9VXFMIszB4rC2xgMpaVWxBOZYjB1 6PxwY5ktxn770bYiBiih3eYaRg68S9PXapMTCuhE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726314AbgHRAyx (ORCPT ); Mon, 17 Aug 2020 20:54:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:38006 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726302AbgHRAyw (ORCPT ); Mon, 17 Aug 2020 20:54:52 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CCC5A2078B; Tue, 18 Aug 2020 00:54:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597712092; bh=VD62CXPwCkmJuAeTqgY5XHb25Dy+4IXcXfQdlHKK0QQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=s/BluTh/RbG2VQ8rEX/6UD+ZEOQBaI/hrDYl1dl+fO8GFvb3oXr8WPPJQxWhw16VU dR3HZ1i63xGJ9NBqIrTVYhuuYJZ0jqd9m9Fliy8pAm1zEvL8tg0BIsk+h1ODXDpEHm TJCYdK5v3IMWbkw9r6gfzQ0V8WbCfBcLY22eUme8= Date: Mon, 17 Aug 2020 20:54:50 -0400 From: Sasha Levin To: Michael Kelley Cc: Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , "wei.liu@kernel.org" , "stable@vger.kernel.org" , Wei Hu , Lorenzo Pieralisi Subject: Re: [PATCH 5.8 298/464] PCI: hv: Fix a timing issue which causes kdump to fail occasionally Message-ID: <20200818005450.GF4122976@sasha-vm> References: <20200817143833.737102804@linuxfoundation.org> <20200817143848.081418490@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Aug 17, 2020 at 11:27:49PM +0000, Michael Kelley wrote: >From: Greg Kroah-Hartman Sent: Monday, August 17, 2020 8:14 AM >> >> From: Wei Hu >> >> [ Upstream commit d6af2ed29c7c1c311b96dac989dcb991e90ee195 ] >> >> Kdump could fail sometime on Hyper-V guest because the retry in >> hv_pci_enter_d0() releases child device structures in hv_pci_bus_exit(). >> >> Although there is a second asynchronous device relations message sending >> from the host, if this message arrives to the guest after >> hv_send_resource_allocated() is called, the retry would fail. >> >> Fix the problem by moving retry to hv_pci_probe() and start the retry >> from hv_pci_query_relations() call. This will cause a device relations >> message to arrive to the guest synchronously; the guest would then be >> able to rebuild the child device structures before calling >> hv_send_resource_allocated(). >> >> Link: >> https://lore.kernel.org/linux-hyperv/20200727071731.18516-1-weh@microsoft.com/ >> Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state") >> Signed-off-by: Wei Hu >> [lorenzo.pieralisi@arm.com: fixed a comment and commit log] >> Signed-off-by: Lorenzo Pieralisi >> Reviewed-by: Michael Kelley >> Signed-off-by: Sasha Levin >> --- >> drivers/pci/controller/pci-hyperv.c | 71 +++++++++++++++-------------- >> 1 file changed, 37 insertions(+), 34 deletions(-) >> > >Greg -- > >Don't backport this patch to 5.8 and earlier. It doesn't break anything, >but it doesn't fully accomplish what was intended either. As such it will >probably need a revision in 5.9. Wei Hu is unavailable for a few days >for personal reasons, so I'm jumping in here on his behalf. I've dropped it, will wait for the fix. -- Thanks, Sasha