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From: Qi Zheng <zhengqi.arch@bytedance.com>
To: daniel@ffwll.ch
Cc: akpm@linux-foundation.org, david@fromorbit.com, tkhai@ya.ru,
	vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org,
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	daniel.vetter@ffwll.ch
Subject: Re: [PATCH v4 43/48] drm/ttm: introduce pool_shrink_rwsem
Date: Wed, 23 Aug 2023 10:59:34 +0800	[thread overview]
Message-ID: <63dc1d86-2a15-6b7e-f63a-63fccb25eae2@bytedance.com> (raw)
In-Reply-To: <ZOS+g51Yx9PsYkGU@phenom.ffwll.local>

Hi Daniel,

On 2023/8/22 21:56, Daniel Vetter wrote:
> On Mon, Aug 07, 2023 at 07:09:31PM +0800, Qi Zheng wrote:
>> Currently, the synchronize_shrinkers() is only used by TTM pool. It only
>> requires that no shrinkers run in parallel.
>>
>> After we use RCU+refcount method to implement the lockless slab shrink,
>> we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all
>> shrinker invocations have seen an update before freeing memory.
>>
>> So we introduce a new pool_shrink_rwsem to implement a private
>> synchronize_shrinkers(), so as to achieve the same purpose.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> 
> On the 5 drm patches (I counted 2 ttm and 3 drivers) for merging through
> some other tree (since I'm assuming that's how this will land):

Yeah, there are 5 drm patches: PATCH v4 07/48 23/48 24/48 25/48 43/48.

> 
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Thanks for your review!

Qi

> 
>> ---
>>   drivers/gpu/drm/ttm/ttm_pool.c | 15 +++++++++++++++
>>   include/linux/shrinker.h       |  2 --
>>   mm/shrinker.c                  | 15 ---------------
>>   3 files changed, 15 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
>> index c9c9618c0dce..38b4c280725c 100644
>> --- a/drivers/gpu/drm/ttm/ttm_pool.c
>> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
>> @@ -74,6 +74,7 @@ static struct ttm_pool_type global_dma32_uncached[MAX_ORDER + 1];
>>   static spinlock_t shrinker_lock;
>>   static struct list_head shrinker_list;
>>   static struct shrinker *mm_shrinker;
>> +static DECLARE_RWSEM(pool_shrink_rwsem);
>>   
>>   /* Allocate pages of size 1 << order with the given gfp_flags */
>>   static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
>> @@ -317,6 +318,7 @@ static unsigned int ttm_pool_shrink(void)
>>   	unsigned int num_pages;
>>   	struct page *p;
>>   
>> +	down_read(&pool_shrink_rwsem);
>>   	spin_lock(&shrinker_lock);
>>   	pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);
>>   	list_move_tail(&pt->shrinker_list, &shrinker_list);
>> @@ -329,6 +331,7 @@ static unsigned int ttm_pool_shrink(void)
>>   	} else {
>>   		num_pages = 0;
>>   	}
>> +	up_read(&pool_shrink_rwsem);
>>   
>>   	return num_pages;
>>   }
>> @@ -572,6 +575,18 @@ void ttm_pool_init(struct ttm_pool *pool, struct device *dev,
>>   }
>>   EXPORT_SYMBOL(ttm_pool_init);
>>   
>> +/**
>> + * synchronize_shrinkers - Wait for all running shrinkers to complete.
>> + *
>> + * This is useful to guarantee that all shrinker invocations have seen an
>> + * update, before freeing memory, similar to rcu.
>> + */
>> +static void synchronize_shrinkers(void)
>> +{
>> +	down_write(&pool_shrink_rwsem);
>> +	up_write(&pool_shrink_rwsem);
>> +}
>> +
>>   /**
>>    * ttm_pool_fini - Cleanup a pool
>>    *
>> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
>> index c55c07c3f0cb..025c8070dd86 100644
>> --- a/include/linux/shrinker.h
>> +++ b/include/linux/shrinker.h
>> @@ -103,8 +103,6 @@ struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...);
>>   void shrinker_register(struct shrinker *shrinker);
>>   void shrinker_free(struct shrinker *shrinker);
>>   
>> -extern void synchronize_shrinkers(void);
>> -
>>   #ifdef CONFIG_SHRINKER_DEBUG
>>   extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker,
>>   						  const char *fmt, ...);
>> diff --git a/mm/shrinker.c b/mm/shrinker.c
>> index 3ab301ff122d..a27779ed3798 100644
>> --- a/mm/shrinker.c
>> +++ b/mm/shrinker.c
>> @@ -650,18 +650,3 @@ void shrinker_free(struct shrinker *shrinker)
>>   	kfree(shrinker);
>>   }
>>   EXPORT_SYMBOL_GPL(shrinker_free);
>> -
>> -/**
>> - * synchronize_shrinkers - Wait for all running shrinkers to complete.
>> - *
>> - * This is equivalent to calling unregister_shrink() and register_shrinker(),
>> - * but atomically and with less overhead. This is useful to guarantee that all
>> - * shrinker invocations have seen an update, before freeing memory, similar to
>> - * rcu.
>> - */
>> -void synchronize_shrinkers(void)
>> -{
>> -	down_write(&shrinker_rwsem);
>> -	up_write(&shrinker_rwsem);
>> -}
>> -EXPORT_SYMBOL(synchronize_shrinkers);
>> -- 
>> 2.30.2
>>
> 

  reply	other threads:[~2023-08-23  3:00 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-07 11:08 [PATCH v4 00/48] use refcount+RCU method to implement lockless slab shrink Qi Zheng
2023-08-07 11:08 ` [PATCH v4 01/48] mm: move some shrinker-related function declarations to mm/internal.h Qi Zheng
2023-08-15  8:36   ` Muchun Song
2023-08-15  9:14     ` Qi Zheng
2023-08-07 11:08 ` [PATCH v4 02/48] mm: vmscan: move shrinker-related code into a separate file Qi Zheng
2023-08-15  8:44   ` Muchun Song
2023-08-07 11:08 ` [PATCH v4 03/48] mm: shrinker: remove redundant shrinker_rwsem in debugfs operations Qi Zheng
2023-08-07 11:08 ` [PATCH v4 04/48] mm: shrinker: add infrastructure for dynamically allocating shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 05/48] kvm: mmu: dynamically allocate the x86-mmu shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 06/48] binder: dynamically allocate the android-binder shrinker Qi Zheng
2023-08-08  2:30   ` Muchun Song
2023-08-07 11:08 ` [PATCH v4 07/48] drm/ttm: dynamically allocate the drm-ttm_pool shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 08/48] xenbus/backend: dynamically allocate the xen-backend shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 09/48] erofs: dynamically allocate the erofs-shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 10/48] f2fs: dynamically allocate the f2fs-shrinker Qi Zheng
2023-08-07 11:08 ` [PATCH v4 11/48] gfs2: dynamically allocate the gfs2-glock shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 12/48] gfs2: dynamically allocate the gfs2-qd shrinker Qi Zheng
2023-08-15  8:56   ` Muchun Song
2023-08-07 11:09 ` [PATCH v4 13/48] NFSv4.2: dynamically allocate the nfs-xattr shrinkers Qi Zheng
2023-08-07 11:09 ` [PATCH v4 14/48] nfs: dynamically allocate the nfs-acl shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 15/48] nfsd: dynamically allocate the nfsd-filecache shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 16/48] quota: dynamically allocate the dquota-cache shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 17/48] ubifs: dynamically allocate the ubifs-slab shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 18/48] rcu: dynamically allocate the rcu-lazy shrinker Qi Zheng
2023-08-07 14:16   ` Joel Fernandes
2023-08-07 11:09 ` [PATCH v4 19/48] rcu: dynamically allocate the rcu-kfree shrinker Qi Zheng
2023-08-07 14:14   ` Joel Fernandes
2023-08-08  2:28   ` Muchun Song
2023-08-07 11:09 ` [PATCH v4 20/48] mm: thp: dynamically allocate the thp-related shrinkers Qi Zheng
2023-08-07 11:09 ` [PATCH v4 21/48] sunrpc: dynamically allocate the sunrpc_cred shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 22/48] mm: workingset: dynamically allocate the mm-shadow shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 23/48] drm/i915: dynamically allocate the i915_gem_mm shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 24/48] drm/msm: dynamically allocate the drm-msm_gem shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 25/48] drm/panfrost: dynamically allocate the drm-panfrost shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 26/48] dm: dynamically allocate the dm-bufio shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 27/48] dm zoned: dynamically allocate the dm-zoned-meta shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 28/48] md/raid5: dynamically allocate the md-raid5 shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 29/48] bcache: dynamically allocate the md-bcache shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 30/48] vmw_balloon: dynamically allocate the vmw-balloon shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 31/48] virtio_balloon: dynamically allocate the virtio-balloon shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 32/48] mbcache: dynamically allocate the mbcache shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 33/48] ext4: dynamically allocate the ext4-es shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 34/48] jbd2,ext4: dynamically allocate the jbd2-journal shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 35/48] nfsd: dynamically allocate the nfsd-client shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 36/48] nfsd: dynamically allocate the nfsd-reply shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 37/48] xfs: dynamically allocate the xfs-buf shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 38/48] xfs: dynamically allocate the xfs-inodegc shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 39/48] xfs: dynamically allocate the xfs-qm shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 40/48] zsmalloc: dynamically allocate the mm-zspool shrinker Qi Zheng
2023-08-07 11:09 ` [PATCH v4 41/48] fs: super: dynamically allocate the s_shrink Qi Zheng
2023-08-07 11:09 ` [PATCH v4 42/48] mm: shrinker: remove old APIs Qi Zheng
2023-08-07 11:09 ` [PATCH v4 43/48] drm/ttm: introduce pool_shrink_rwsem Qi Zheng
2023-08-22 13:56   ` Daniel Vetter
2023-08-23  2:59     ` Qi Zheng [this message]
2023-08-07 11:09 ` [PATCH v4 44/48] mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred} Qi Zheng
2023-08-08  2:12   ` Dave Chinner
2023-08-08  6:32     ` Qi Zheng
2023-08-07 11:09 ` [PATCH v4 45/48] mm: shrinker: make global slab shrink lockless Qi Zheng
2023-08-07 23:28   ` Dave Chinner
2023-08-08  2:24   ` Dave Chinner
2023-08-08  7:22     ` Qi Zheng
2023-08-07 11:09 ` [PATCH v4 46/48] mm: shrinker: make memcg " Qi Zheng
2023-08-08  2:44   ` Dave Chinner
2023-08-08  7:50     ` Qi Zheng
2023-08-07 11:09 ` [PATCH v4 47/48] mm: shrinker: hold write lock to reparent shrinker nr_deferred Qi Zheng
2023-08-07 11:09 ` [PATCH v4 48/48] mm: shrinker: convert shrinker_rwsem to mutex Qi Zheng

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