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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A05D5C433DF for ; Mon, 6 Jul 2020 15:10:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70A7D20723 for ; Mon, 6 Jul 2020 15:10:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594048247; bh=8C2qAl9kUOeQT9wyLID3MuIDXLXIVzJK6cSedO1jKb8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SFR09gvX3acJOt0y5UX29HXqqor7xWZHXxJ4EQ5s0R/11jRW7+GBG22uU7QvTekMZ Z7QVdA7BTAXfJLP1TqsKe9/fFbQUSWAHVGj3TZhcQ3xP7J8ooi1Nr3G/vz448Fvb49 DO4DXjfdB2HEgpx62WlBAQg6YGLcUC3OFt8cO2kU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729269AbgGFPKr (ORCPT ); Mon, 6 Jul 2020 11:10:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:33138 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729140AbgGFPKq (ORCPT ); Mon, 6 Jul 2020 11:10:46 -0400 Received: from localhost (unknown [122.182.251.219]) (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 50663206CD; Mon, 6 Jul 2020 15:10:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594048246; bh=8C2qAl9kUOeQT9wyLID3MuIDXLXIVzJK6cSedO1jKb8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LNfkzaw+URH7MQyQbhwZp1IRzmusnXAj7S/Ee4WGl5r/jQz2TdZJZq0Fm+yvBin8o vyUw9Rcoqimquebx5PzcsRj5xYNcTAGGN7IcZOkTGfxc7xc1fjW//XfZd7Aw+uRfhH Ox3mUxPuyLlGFUIVJzI/pNRHdDZA9LplQARFNxR8= Date: Mon, 6 Jul 2020 20:40:41 +0530 From: Vinod Koul To: Dave Jiang Cc: Arnd Bergmann , Naresh Kamboju , linux-serial@vger.kernel.org, open list , Jiri Slaby , linux-arm-msm , linux-tegra , jirislaby@kernel.org, Greg Kroah-Hartman , Andy Gross , Bjorn Andersson , ldewangan@nvidia.com, Thierry Reding , Jon Hunter , Qian Cai , lkft-triage@lists.linaro.org Subject: Re: [qemu] boot failed: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Message-ID: <20200706151041.GL633187@vkoul-mobl> References: <8c50799e-d0ba-626a-5627-5ff4e5825f6a@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8c50799e-d0ba-626a-5627-5ff4e5825f6a@intel.com> Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 06-07-20, 07:33, Dave Jiang wrote: > > I don't see anything suspicious in dmaengine drivers, but there is a > > recent series > > from Dave Jiang that might explain it. Could you try reverting commit > > deb9541f5052 ("dmaengine: check device and channel list for empty")? > > > > I think the broken change is this one: > > > > @@ -819,6 +850,11 @@ struct dma_chan *dma_request_chan(struct device > > *dev, const char *name) > > > > /* Try to find the channel via the DMA filter map(s) */ > > mutex_lock(&dma_list_mutex); > > + if (list_empty(&dma_device_list)) { > > + mutex_unlock(&dma_list_mutex); > > + return NULL; > > + } > > + > > list_for_each_entry_safe(d, _d, &dma_device_list, global_node) { > > dma_cap_mask_t mask; > > const struct dma_slave_map *map = dma_filter_match(d, > > name, dev); > > > > which needs to return an error code like -ENODEV instead of NULL. There > > may be other changes in the same patch that introduce the same bug > > elsewhere. > > > > Arnd > > > > Vinod, > Do you want a diff fix or a revision of the patch for the fix? Diff fix please -- ~Vinod