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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 0EDF3C433ED for ; Wed, 19 May 2021 15:01:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E60A36135A for ; Wed, 19 May 2021 15:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347805AbhESPCV (ORCPT ); Wed, 19 May 2021 11:02:21 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:42374 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229808AbhESPCU (ORCPT ); Wed, 19 May 2021 11:02:20 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1621436460; h=Content-Type: MIME-Version: Message-ID: In-Reply-To: Date: References: Subject: Cc: To: From: Sender; bh=638YVhE9uQAJ1yHYklSQlB/9IUMfzjqyYCUeaH69iag=; b=JagaSfnkfQ7IWmr0l4qgdRu8x4H6iFM0y4gP0dgOR6tCA36b6k9mbpIA54VX39mpzViyvbq6 8C0yDowShSJ1+/y4LzkZrA75YnI25K4aMS7X8ZymEs2ZzC942zjemcmlO0jvSkuKDUdYu6Kp lSUxj2Zs+HfqMfEahQyODAmJsNI= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n06.prod.us-east-1.postgun.com with SMTP id 60a52809063320cd1387e32f (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 19 May 2021 15:00:25 GMT Sender: kvalo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9CA42C43146; Wed, 19 May 2021 15:00:24 +0000 (UTC) Received: from tynnyri.adurom.net (tynnyri.adurom.net [51.15.11.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: kvalo) by smtp.codeaurora.org (Postfix) with ESMTPSA id 14244C433D3; Wed, 19 May 2021 15:00:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 14244C433D3 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=kvalo@codeaurora.org From: Kalle Valo To: Christoph Hellwig Cc: Linus Torvalds , kernel test robot , Thomas =?utf-8?Q?Hellstr=C3=B6m?= , Serge Belyshev , Chris Wilson , Daniel Vetter , Jani Nikula , Joonas Lahtinen , Peter Zijlstra , Rodrigo Vivi , Andrew Morton , LKML , lkp@lists.01.org, kernel test robot , regressions@lists.linux.dev Subject: Re: [i915] b12d691ea5: kernel_BUG_at_mm/memory.c References: <20210519024322.GA29704@xsang-OptiPlex-9020> <20210519133330.GA14452@lst.de> Date: Wed, 19 May 2021 18:00:14 +0300 In-Reply-To: <20210519133330.GA14452@lst.de> (Christoph Hellwig's message of "Wed, 19 May 2021 15:33:30 +0200") Message-ID: <87y2ca6a69.fsf@tynnyri.adurom.net> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > On Tue, May 18, 2021 at 04:58:31PM -1000, Linus Torvalds wrote: >> On Tue, May 18, 2021 at 4:26 PM kernel test robot wrote: >> > >> > commit: b12d691ea5e01db42ccf3b4207e57cb3ce7cfe91 ("i915: fix remap_io_sg to verify the pgprot") >> > [...] >> > [ 778.550996] kernel BUG at mm/memory.c:2183! >> > [ 778.559015] RIP: 0010:remap_pfn_range_notrack >> > (kbuild/src/consumer/mm/memory.c:2183 >> > kbuild/src/consumer/mm/memory.c:2211 >> > kbuild/src/consumer/mm/memory.c:2233 >> > kbuild/src/consumer/mm/memory.c:2255 >> > kbuild/src/consumer/mm/memory.c:2311) >> > [ 778.688951] remap_pfn_range (kbuild/src/consumer/mm/memory.c:2342) >> > [ 778.692700] remap_io_sg (kbuild/src/consumer/drivers/gpu/drm/i915/i915_mm.c:71) i915 >> >> Yeah, so that BUG_ON() checks that theer isn't any old mapping there. >> >> You can't just remap over an old one, but it does seem like that is >> exactly what commit b12d691ea5e0 ("i915: fix remap_io_sg to verify the >> pgprot") ends up doing. >> >> So the code used to just do "apply_to_page_range()", which admittedly >> was odd too. But it didn't mind having old mappings and re-applying >> something over them. >> >> Converting it to use remap_pfn_range() does look better, but it kind >> of depends on it ever being done *once*. But the caller seems to very >> much remap the whole vmsa at fault time, so... >> >> I don't know what the right thing to do here is, because I don't know >> the invalidation logic and when faults happen. >> >> I see that there is another thread about different issues on the >> intel-gfx list. Adding a few people to this kernel test robot thread >> too. >> >> I'd be inclined to revert the commits as "not ready yet", but it would >> be better if somebody can go "yeah, this should be done properly like >> X". > > I think reverting just this commit for now is the best thing. Yes, please revert it if there's no quick fix. On my Dell XPS 13 9310 laptop (with Debian 10) X won't start until I revert commit b12d691ea5e0, so this is a major issue. Also adding the new regressions list, as this is an i915 regression introduced in v5.13-rc1. -- https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches