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=-6.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 E1135C4363A for ; Mon, 5 Oct 2020 16:17:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1EDA20756 for ; Mon, 5 Oct 2020 16:17:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Wevs5QjZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727224AbgJEQRO (ORCPT ); Mon, 5 Oct 2020 12:17:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727211AbgJEQRO (ORCPT ); Mon, 5 Oct 2020 12:17:14 -0400 Received: from mail-vk1-xa43.google.com (mail-vk1-xa43.google.com [IPv6:2607:f8b0:4864:20::a43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC6BEC0613CE; Mon, 5 Oct 2020 09:17:13 -0700 (PDT) Received: by mail-vk1-xa43.google.com with SMTP id q13so1877582vkd.0; Mon, 05 Oct 2020 09:17:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=QHfrL0vnZkCKeKCtvZvw1Ln46V81wH7BkrurZ5zUFZk=; b=Wevs5QjZluOaRR1AOZGAEhuHk0w+X16ebwlSNMFfb39m/CXX9klz9WZCmFoGZHnkrU d4elvjxcQpllgt3+nlR3BH087M2PDxC8iLxhWegBseS38D6ZNgrULbb/sN09ojA8fSkk j+vHB8rG2dkhfC+HkV0Dtl78x8U6BuKZR63PCPu+f0gRNQVvy4MtAZxrfbD274IyBaBJ 9chqecOlrYAlPhUrNEZeIX9hlwjFlYe8wfdjxjR+XA2icGGExvaTunU0qxG+LdS0wxMC u26TrR3sjLHiOP1AH2KiBnpEgeGwgBhTjBbV7Rm0cJTQ3e11kgNE2fYKohGg8SirpGnL wkYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=QHfrL0vnZkCKeKCtvZvw1Ln46V81wH7BkrurZ5zUFZk=; b=XVvWJfxajUYGd0RIDlK0YFDck2ycizUzTW00RVA5JLbPcpMmvjAON6zrUYZc1hYz0l /k5NkcZNHQOjEUyDHlcFilzb5+Jogo/YPCiET0dTxAKeCnsKmF3oUTBVGBm2BRnwF9Uh wapynp4/z7AbCdFFqPINMUrXMN/+X5HVCyxZ1w/T8BtIcAT1EbnOpznUNXGv4MHv8G/7 28wuN8SW2hm/dtbr4EhcKLEYPZ2J5CNLe6YMv/7u1LGxP5X7iq5I2tyb+x4ynck1NAcx Ql1RmBKPFPmMMr6wS7R09xiZxJpqpoL8PULB/XGu9HZ21FPs0K9NylnmW8QNrfkXPJtn NBJA== X-Gm-Message-State: AOAM531ojA8j73g7HJcIBlpvu+1N33vr0lElN2aThkLgIW8mrVRV2rQg rrMBl8YdXzGZIcaIPHXiQHAR6b5jPFV/o4fhM6o= X-Google-Smtp-Source: ABdhPJznNzIHUiu7fkeGWHOPhlZ6vkhgyjAwLPnbGS9WDmUCIW5CFvWNDVtMLRxauYUQ5TUjesyG7FHNdP49l4+whVg= X-Received: by 2002:a1f:a290:: with SMTP id l138mr202080vke.9.1601914632799; Mon, 05 Oct 2020 09:17:12 -0700 (PDT) MIME-Version: 1.0 References: <20201004192152.3298573-1-robdclark@gmail.com> <20201005092419.15608-1-hdanton@sina.com> <20201005140203.GS438822@phenom.ffwll.local> In-Reply-To: <20201005140203.GS438822@phenom.ffwll.local> From: =?UTF-8?Q?Kristian_H=C3=B8gsberg?= Date: Mon, 5 Oct 2020 18:17:01 +0200 Message-ID: Subject: Re: [PATCH 13/14] drm/msm: Drop struct_mutex in shrinker path To: Hillf Danton , Rob Clark , dri-devel , Rob Clark , Sean Paul , David Airlie , "open list:DRM DRIVER FOR MSM ADRENO GPU" , freedreno , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Mon, Oct 5, 2020 at 4:02 PM Daniel Vetter wrote: > > On Mon, Oct 05, 2020 at 05:24:19PM +0800, Hillf Danton wrote: > > > > On Sun, 4 Oct 2020 12:21:45 > > > From: Rob Clark > > > > > > Now that the inactive_list is protected by mm_lock, and everything > > > else on per-obj basis is protected by obj->lock, we no longer depend > > > on struct_mutex. > > > > > > Signed-off-by: Rob Clark > > > --- > > > drivers/gpu/drm/msm/msm_gem.c | 1 - > > > drivers/gpu/drm/msm/msm_gem_shrinker.c | 54 -------------------------- > > > 2 files changed, 55 deletions(-) > > > > > [...] > > > > > @@ -71,13 +33,8 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) > > > { > > > struct msm_drm_private *priv = > > > container_of(shrinker, struct msm_drm_private, shrinker); > > > - struct drm_device *dev = priv->dev; > > > struct msm_gem_object *msm_obj; > > > unsigned long freed = 0; > > > - bool unlock; > > > - > > > - if (!msm_gem_shrinker_lock(dev, &unlock)) > > > - return SHRINK_STOP; > > > > > > mutex_lock(&priv->mm_lock); > > > > Better if the change in behavior is documented that SHRINK_STOP will > > no longer be needed. > > btw I read through this and noticed you have your own obj lock, plus > mutex_lock_nested. I strongly recommend to just cut over to dma_resv_lock > for all object lock needs (soc drivers have been terrible with this > unfortuntaly), and in the shrinker just use dma_resv_trylock instead of > trying to play clever games outsmarting lockdep. > > I recently wrote an entire blog length rant on why I think > mutex_lock_nested is too dangerous to be useful: > > https://blog.ffwll.ch/2020/08/lockdep-false-positives.html > > Not anything about this here, just general comment. The problem extends to > shmem helpers and all that also having their own locks for everything. This is definitely a tangible improvement though - very happy to see msm_gem_shrinker_lock() go. Reviewed-by: Kristian H. Kristensen > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel 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=-6.3 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 78BEDC47095 for ; Mon, 5 Oct 2020 16:17:16 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0A95E206DD for ; 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Mon, 05 Oct 2020 09:17:12 -0700 (PDT) MIME-Version: 1.0 References: <20201004192152.3298573-1-robdclark@gmail.com> <20201005092419.15608-1-hdanton@sina.com> <20201005140203.GS438822@phenom.ffwll.local> In-Reply-To: <20201005140203.GS438822@phenom.ffwll.local> From: =?UTF-8?Q?Kristian_H=C3=B8gsberg?= Date: Mon, 5 Oct 2020 18:17:01 +0200 Message-ID: Subject: Re: [PATCH 13/14] drm/msm: Drop struct_mutex in shrinker path To: Hillf Danton , Rob Clark , dri-devel , Rob Clark , Sean Paul , David Airlie , "open list:DRM DRIVER FOR MSM ADRENO GPU" , freedreno , LKML X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Oct 5, 2020 at 4:02 PM Daniel Vetter wrote: > > On Mon, Oct 05, 2020 at 05:24:19PM +0800, Hillf Danton wrote: > > > > On Sun, 4 Oct 2020 12:21:45 > > > From: Rob Clark > > > > > > Now that the inactive_list is protected by mm_lock, and everything > > > else on per-obj basis is protected by obj->lock, we no longer depend > > > on struct_mutex. > > > > > > Signed-off-by: Rob Clark > > > --- > > > drivers/gpu/drm/msm/msm_gem.c | 1 - > > > drivers/gpu/drm/msm/msm_gem_shrinker.c | 54 -------------------------- > > > 2 files changed, 55 deletions(-) > > > > > [...] > > > > > @@ -71,13 +33,8 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) > > > { > > > struct msm_drm_private *priv = > > > container_of(shrinker, struct msm_drm_private, shrinker); > > > - struct drm_device *dev = priv->dev; > > > struct msm_gem_object *msm_obj; > > > unsigned long freed = 0; > > > - bool unlock; > > > - > > > - if (!msm_gem_shrinker_lock(dev, &unlock)) > > > - return SHRINK_STOP; > > > > > > mutex_lock(&priv->mm_lock); > > > > Better if the change in behavior is documented that SHRINK_STOP will > > no longer be needed. > > btw I read through this and noticed you have your own obj lock, plus > mutex_lock_nested. I strongly recommend to just cut over to dma_resv_lock > for all object lock needs (soc drivers have been terrible with this > unfortuntaly), and in the shrinker just use dma_resv_trylock instead of > trying to play clever games outsmarting lockdep. > > I recently wrote an entire blog length rant on why I think > mutex_lock_nested is too dangerous to be useful: > > https://blog.ffwll.ch/2020/08/lockdep-false-positives.html > > Not anything about this here, just general comment. The problem extends to > shmem helpers and all that also having their own locks for everything. This is definitely a tangible improvement though - very happy to see msm_gem_shrinker_lock() go. Reviewed-by: Kristian H. Kristensen > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel