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Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Mimecast-Bulk-Signature: yes X-Mimecast-Spam-Signature: bulk X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mailman-Approved-At: Tue, 25 Jul 2023 06:42:42 +0000 Subject: [dm-devel] [PATCH v2 42/47] drm/ttm: introduce pool_shrink_rwsem X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, dm-devel@redhat.com, linux-mtd@lists.infradead.org, x86@kernel.org, cluster-devel@redhat.com, xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org, linux-arm-msm@vger.kernel.org, rcu@vger.kernel.org, linux-bcache@vger.kernel.org, Qi Zheng , linux-raid@vger.kernel.org, linux-nfs@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: bytedance.com 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 Reviewed-by: Muchun Song --- 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 e1eb73d0b72a..8a35fd48ec46 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 e464b4e9be0e..23ea9360c5d8 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -105,8 +105,6 @@ void shrinker_free_non_registered(struct shrinker *shrinker); void shrinker_register(struct shrinker *shrinker); void shrinker_unregister(struct shrinker *shrinker); -extern void synchronize_shrinkers(void); - #ifdef CONFIG_SHRINKER_DEBUG extern int shrinker_debugfs_add(struct shrinker *shrinker); extern struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker, diff --git a/mm/shrinker.c b/mm/shrinker.c index 2f3635ad1b45..3c4d3fe2fa17 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -660,18 +660,3 @@ void shrinker_unregister(struct shrinker *shrinker) kfree(shrinker); } EXPORT_SYMBOL(shrinker_unregister); - -/** - * 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);