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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38959C433EF for ; Wed, 13 Apr 2022 06:05:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232896AbiDMGIO (ORCPT ); Wed, 13 Apr 2022 02:08:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232834AbiDMGIM (ORCPT ); Wed, 13 Apr 2022 02:08:12 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A379E35A80 for ; Tue, 12 Apr 2022 23:05:51 -0700 (PDT) Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: dmitry.osipenko) with ESMTPSA id 3EE3C1F44C9C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1649829950; bh=h6yCUcAcN6iaR3DQkh+xpCyBQk8JfcLMxbGWf++mfDM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=jMVQuRfWn5ob7ywAWnQ4xvadET+t9PxuKd4Yumb2zwEGZwGkefQlF4p+oKw8vT8gt AbQ0XoyYyRYvYxIUKG86ENbVE3riGczfeVt617sOMoKKc7uLvEaD1omvHHkkmCl1ra 6vDBajXKYLJdG2wl0n08JIB4LohicDYP4LNMgYnvUhVAOZjIvWwhz+GbQ4N2AEizv5 CdP3hDzqnBHbm1Yjg7WYACdDDSWcyp056qAACKATm+T2Hrsn6kjetJt2Np3/bRrxu9 QCtJEuW1lz4wA0HV44Bw3KCC4gn3U85I1OqPaifplAgo3iZMFRVie0zpS7P6nCb9+p QRFaxCjhyxBIg== Message-ID: <7f0d7ade-1d59-2c43-c1b2-1fa847eb741a@collabora.com> Date: Wed, 13 Apr 2022 09:05:46 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v1] drm/scheduler: Don't kill jobs in interrupt context Content-Language: en-US To: Erico Nunes , Andrey Grodzovsky Cc: David Airlie , Daniel Vetter , Tomeu Vizoso , Steven Price , Rob Herring , Alyssa Rosenzweig , Rob Clark , Dmitry Osipenko , linux-kernel , dri-devel , Qiang Yu References: <20220411221536.283312-1-dmitry.osipenko@collabora.com> <064d8958-a288-64e1-b2a4-c2302a456d5b@amd.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/13/22 01:59, Erico Nunes wrote: > On Tue, Apr 12, 2022 at 9:41 PM Andrey Grodzovsky > wrote: >> >> >> On 2022-04-12 14:20, Dmitry Osipenko wrote: >>> On 4/12/22 19:51, Andrey Grodzovsky wrote: >>>> On 2022-04-11 18:15, Dmitry Osipenko wrote: >>>>> Interrupt context can't sleep. Drivers like Panfrost and MSM are taking >>>>> mutex when job is released, and thus, that code can sleep. This results >>>>> into "BUG: scheduling while atomic" if locks are contented while job is >>>>> freed. There is no good reason for releasing scheduler's jobs in IRQ >>>>> context, hence use normal context to fix the trouble. >>>> >>>> I am not sure this is the beast Idea to leave job's sw fence signalling >>>> to be >>>> executed in system_wq context which is prone to delays of executing >>>> various work items from around the system. Seems better to me to leave the >>>> fence signaling within the IRQ context and offload only the job freeing or, >>>> maybe handle rescheduling to thread context within drivers implemention >>>> of .free_job cb. Not really sure which is the better. >>> We're talking here about killing jobs when driver destroys context, >>> which doesn't feel like it needs to be a fast path. I could move the >>> signalling into drm_sched_entity_kill_jobs_cb() and use unbound wq, but >>> do we really need this for a slow path? >> >> >> You can't move the signaling back to drm_sched_entity_kill_jobs_cb >> since this will bring back the lockdep splat that 'drm/sched: Avoid >> lockdep spalt on killing a processes' >> was fixing. >> >> I see your point and i guess we can go this way too. Another way would >> be to add to >> panfrost and msm job a work_item and reschedule to thread context from >> within their >> .free_job callbacks but that probably to cumbersome to be justified here. > > FWIW since this mentioned individual drivers, commit 'drm/sched: Avoid > lockdep spalt on killing a processes' also introduced problems for > lima. > There were some occurrences in our CI > https://gitlab.freedesktop.org/mesa/mesa/-/jobs/20980982/raw . > Later I found it also reproducible on normal usage when just closing > applications, so it may be affecting users too. > > I tested this patch and looks like it fixes things for lima. This patch indeed should fix that lima bug. Feel free to give yours tested-by :)