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Message-ID: <b941338c-56e7-65e7-da45-bfefc484ad80@bytedance.com>
Date: Wed, 26 Jul 2023 17:31:14 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Muchun Song <muchun.song@...ux.dev>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
kvm@...r.kernel.org, xen-devel@...ts.xenproject.org,
linux-erofs@...ts.ozlabs.org,
linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
linux-nfs@...r.kernel.org, linux-mtd@...ts.infradead.org,
rcu@...r.kernel.org, netdev@...r.kernel.org,
dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
dm-devel@...hat.com, linux-raid@...r.kernel.org,
linux-bcache@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
yujie.liu@...el.com, gregkh@...uxfoundation.org
Subject: Re: [PATCH v2 23/47] drm/msm: dynamically allocate the drm-msm_gem
shrinker
On 2023/7/26 15:24, Muchun Song wrote:
>
>
> On 2023/7/24 17:43, Qi Zheng wrote:
>> In preparation for implementing lockless slab shrink, use new APIs to
>> dynamically allocate the drm-msm_gem 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 msm_drm_private.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
>
> Reviewed-by: Muchun Song <songmuchun@...edance.com>
>
> A nit bellow.
>
>> ---
>> drivers/gpu/drm/msm/msm_drv.c | 4 ++-
>> drivers/gpu/drm/msm/msm_drv.h | 4 +--
>> drivers/gpu/drm/msm/msm_gem_shrinker.c | 36 ++++++++++++++++----------
>> 3 files changed, 28 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/msm_drv.c
>> b/drivers/gpu/drm/msm/msm_drv.c
>> index 891eff8433a9..7f6933be703f 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.c
>> +++ b/drivers/gpu/drm/msm/msm_drv.c
>> @@ -461,7 +461,9 @@ static int msm_drm_init(struct device *dev, const
>> struct drm_driver *drv)
>> if (ret)
>> goto err_msm_uninit;
>> - msm_gem_shrinker_init(ddev);
>> + ret = msm_gem_shrinker_init(ddev);
>> + if (ret)
>> + goto err_msm_uninit;
>> if (priv->kms_init) {
>> ret = priv->kms_init(ddev);
>> diff --git a/drivers/gpu/drm/msm/msm_drv.h
>> b/drivers/gpu/drm/msm/msm_drv.h
>> index e13a8cbd61c9..84523d4a1e58 100644
>> --- a/drivers/gpu/drm/msm/msm_drv.h
>> +++ b/drivers/gpu/drm/msm/msm_drv.h
>> @@ -217,7 +217,7 @@ struct msm_drm_private {
>> } vram;
>> struct notifier_block vmap_notifier;
>> - struct shrinker shrinker;
>> + struct shrinker *shrinker;
>> struct drm_atomic_state *pm_state;
>> @@ -279,7 +279,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev,
>> void *data,
>> unsigned long msm_gem_shrinker_shrink(struct drm_device *dev,
>> unsigned long nr_to_scan);
>> #endif
>> -void msm_gem_shrinker_init(struct drm_device *dev);
>> +int msm_gem_shrinker_init(struct drm_device *dev);
>> void msm_gem_shrinker_cleanup(struct drm_device *dev);
>> int msm_gem_prime_mmap(struct drm_gem_object *obj, struct
>> vm_area_struct *vma);
>> diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c
>> b/drivers/gpu/drm/msm/msm_gem_shrinker.c
>> index f38296ad8743..7daab1298c11 100644
>> --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
>> +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
>> @@ -34,8 +34,7 @@ static bool can_block(struct shrink_control *sc)
>> static unsigned long
>> msm_gem_shrinker_count(struct shrinker *shrinker, struct
>> shrink_control *sc)
>> {
>> - struct msm_drm_private *priv =
>> - container_of(shrinker, struct msm_drm_private, shrinker);
>> + struct msm_drm_private *priv = shrinker->private_data;
>> unsigned count = priv->lru.dontneed.count;
>> if (can_swap())
>> @@ -100,8 +99,7 @@ active_evict(struct drm_gem_object *obj)
>> static unsigned long
>> 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 msm_drm_private *priv = shrinker->private_data;
>> struct {
>> struct drm_gem_lru *lru;
>> bool (*shrink)(struct drm_gem_object *obj);
>> @@ -148,10 +146,11 @@ msm_gem_shrinker_shrink(struct drm_device *dev,
>> unsigned long nr_to_scan)
>> struct shrink_control sc = {
>> .nr_to_scan = nr_to_scan,
>> };
>> - int ret;
>> + unsigned long ret = SHRINK_STOP;
>> fs_reclaim_acquire(GFP_KERNEL);
>> - ret = msm_gem_shrinker_scan(&priv->shrinker, &sc);
>> + if (priv->shrinker)
>> + ret = msm_gem_shrinker_scan(priv->shrinker, &sc);
>> fs_reclaim_release(GFP_KERNEL);
>> return ret;
>> @@ -210,16 +209,27 @@ msm_gem_shrinker_vmap(struct notifier_block *nb,
>> unsigned long event, void *ptr)
>> *
>> * This function registers and sets up the msm shrinker.
>> */
>> -void msm_gem_shrinker_init(struct drm_device *dev)
>> +int msm_gem_shrinker_init(struct drm_device *dev)
>> {
>> struct msm_drm_private *priv = dev->dev_private;
>> - priv->shrinker.count_objects = msm_gem_shrinker_count;
>> - priv->shrinker.scan_objects = msm_gem_shrinker_scan;
>> - priv->shrinker.seeks = DEFAULT_SEEKS;
>> - WARN_ON(register_shrinker(&priv->shrinker, "drm-msm_gem"));
>> +
>> + priv->shrinker = shrinker_alloc(0, "drm-msm_gem");
>> + if (!priv->shrinker) {
>
> Just "if (WARN_ON(!priv->shrinker))"
As suggested by Steven Pric in patch #24, this warning is
unnecessary, so I will remove it in the next version.
>
>> + WARN_ON(1);
>> + return -ENOMEM;
>> + }
>> +
>> + priv->shrinker->count_objects = msm_gem_shrinker_count;
>> + priv->shrinker->scan_objects = msm_gem_shrinker_scan;
>> + priv->shrinker->seeks = DEFAULT_SEEKS;
>> + priv->shrinker->private_data = priv;
>> +
>> + shrinker_register(priv->shrinker);
>> priv->vmap_notifier.notifier_call = msm_gem_shrinker_vmap;
>> WARN_ON(register_vmap_purge_notifier(&priv->vmap_notifier));
>> +
>> + return 0;
>> }
>> /**
>> @@ -232,8 +242,8 @@ void msm_gem_shrinker_cleanup(struct drm_device *dev)
>> {
>> struct msm_drm_private *priv = dev->dev_private;
>> - if (priv->shrinker.nr_deferred) {
>> + if (priv->shrinker) {
>> WARN_ON(unregister_vmap_purge_notifier(&priv->vmap_notifier));
>> - unregister_shrinker(&priv->shrinker);
>> + shrinker_unregister(priv->shrinker);
>> }
>> }
>
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