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 17DB1C41513 for ; Mon, 24 Jul 2023 11:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230280AbjGXLSJ (ORCPT ); Mon, 24 Jul 2023 07:18:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229813AbjGXLSI (ORCPT ); Mon, 24 Jul 2023 07:18:08 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 24B84E65; Mon, 24 Jul 2023 04:17:47 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B206CDE0; Mon, 24 Jul 2023 04:18:29 -0700 (PDT) Received: from [10.57.34.62] (unknown [10.57.34.62]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C518B3F5A1; Mon, 24 Jul 2023 04:17:39 -0700 (PDT) Message-ID: Date: Mon, 24 Jul 2023 12:17:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 24/47] drm/panfrost: dynamically allocate the drm-panfrost shrinker To: Qi Zheng , akpm@linux-foundation.org, david@fromorbit.com, tkhai@ya.ru, vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org, brauner@kernel.org, paulmck@kernel.org, tytso@mit.edu, cel@kernel.org, senozhatsky@chromium.org, yujie.liu@intel.com, gregkh@linuxfoundation.org, muchun.song@linux.dev Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-mtd@lists.infradead.org, rcu@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-bcache@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org References: <20230724094354.90817-1-zhengqi.arch@bytedance.com> <20230724094354.90817-25-zhengqi.arch@bytedance.com> Content-Language: en-GB From: Steven Price In-Reply-To: <20230724094354.90817-25-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 24/07/2023 10:43, Qi Zheng wrote: > In preparation for implementing lockless slab shrink, use new APIs to > dynamically allocate the drm-panfrost shrinker, so that it can be freed > asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU > read-side critical section when releasing the struct panfrost_device. > > Signed-off-by: Qi Zheng One nit below, but otherwise: Reviewed-by: Steven Price > --- > drivers/gpu/drm/panfrost/panfrost_device.h | 2 +- > drivers/gpu/drm/panfrost/panfrost_drv.c | 6 +++- > drivers/gpu/drm/panfrost/panfrost_gem.h | 2 +- > .../gpu/drm/panfrost/panfrost_gem_shrinker.c | 32 ++++++++++++------- > 4 files changed, 27 insertions(+), 15 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h > index b0126b9fbadc..e667e5689353 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_device.h > +++ b/drivers/gpu/drm/panfrost/panfrost_device.h > @@ -118,7 +118,7 @@ struct panfrost_device { > > struct mutex shrinker_lock; > struct list_head shrinker_list; > - struct shrinker shrinker; > + struct shrinker *shrinker; > > struct panfrost_devfreq pfdevfreq; > }; > diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c > index bbada731bbbd..f705bbdea360 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_drv.c > +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c > @@ -598,10 +598,14 @@ static int panfrost_probe(struct platform_device *pdev) > if (err < 0) > goto err_out1; > > - panfrost_gem_shrinker_init(ddev); > + err = panfrost_gem_shrinker_init(ddev); > + if (err) > + goto err_out2; > > return 0; > > +err_out2: > + drm_dev_unregister(ddev); > err_out1: > pm_runtime_disable(pfdev->dev); > panfrost_device_fini(pfdev); > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h > index ad2877eeeccd..863d2ec8d4f0 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem.h > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h > @@ -81,7 +81,7 @@ panfrost_gem_mapping_get(struct panfrost_gem_object *bo, > void panfrost_gem_mapping_put(struct panfrost_gem_mapping *mapping); > void panfrost_gem_teardown_mappings_locked(struct panfrost_gem_object *bo); > > -void panfrost_gem_shrinker_init(struct drm_device *dev); > +int panfrost_gem_shrinker_init(struct drm_device *dev); > void panfrost_gem_shrinker_cleanup(struct drm_device *dev); > > #endif /* __PANFROST_GEM_H__ */ > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c > index bf0170782f25..9a90dfb5301f 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c > +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c > @@ -18,8 +18,7 @@ > static unsigned long > panfrost_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) > { > - struct panfrost_device *pfdev = > - container_of(shrinker, struct panfrost_device, shrinker); > + struct panfrost_device *pfdev = shrinker->private_data; > struct drm_gem_shmem_object *shmem; > unsigned long count = 0; > > @@ -65,8 +64,7 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj) > static unsigned long > panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) > { > - struct panfrost_device *pfdev = > - container_of(shrinker, struct panfrost_device, shrinker); > + struct panfrost_device *pfdev = shrinker->private_data; > struct drm_gem_shmem_object *shmem, *tmp; > unsigned long freed = 0; > > @@ -97,13 +95,24 @@ panfrost_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) > * > * This function registers and sets up the panfrost shrinker. > */ > -void panfrost_gem_shrinker_init(struct drm_device *dev) > +int panfrost_gem_shrinker_init(struct drm_device *dev) > { > struct panfrost_device *pfdev = dev->dev_private; > - pfdev->shrinker.count_objects = panfrost_gem_shrinker_count; > - pfdev->shrinker.scan_objects = panfrost_gem_shrinker_scan; > - pfdev->shrinker.seeks = DEFAULT_SEEKS; > - WARN_ON(register_shrinker(&pfdev->shrinker, "drm-panfrost")); > + > + pfdev->shrinker = shrinker_alloc(0, "drm-panfrost"); > + if (!pfdev->shrinker) { > + WARN_ON(1); I don't think this WARN_ON is particularly useful - if there's a failed memory allocation we should see output from the kernel anyway. And we're changing the semantics from "continue just without a shrinker" (which argueably justifies the warning) to "probe fails, device doesn't work" which will be obvious to the user so I don't feel we need the additional warn. > + return -ENOMEM; > + } > + > + pfdev->shrinker->count_objects = panfrost_gem_shrinker_count; > + pfdev->shrinker->scan_objects = panfrost_gem_shrinker_scan; > + pfdev->shrinker->seeks = DEFAULT_SEEKS; > + pfdev->shrinker->private_data = pfdev; > + > + shrinker_register(pfdev->shrinker); > + > + return 0; > } > > /** > @@ -116,7 +125,6 @@ void panfrost_gem_shrinker_cleanup(struct drm_device *dev) > { > struct panfrost_device *pfdev = dev->dev_private; > > - if (pfdev->shrinker.nr_deferred) { > - unregister_shrinker(&pfdev->shrinker); > - } > + if (pfdev->shrinker) > + shrinker_unregister(pfdev->shrinker); > }