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Mon, 07 Aug 2023 04:19:07 -0700 (PDT) From: Qi Zheng To: 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, steven.price@arm.com, cel@kernel.org, senozhatsky@chromium.org, yujie.liu@intel.com, gregkh@linuxfoundation.org, muchun.song@linux.dev, simon.horman@corigine.com, dlemoal@kernel.org 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, Qi Zheng , Muchun Song Subject: [PATCH v4 43/48] drm/ttm: introduce pool_shrink_rwsem Date: Mon, 7 Aug 2023 19:09:31 +0800 Message-Id: <20230807110936.21819-44-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230807110936.21819-1-zhengqi.arch@bytedance.com> References: <20230807110936.21819-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230807_041912_288070_81DA8A43 X-CRM114-Status: GOOD ( 12.36 ) X-Spam-Score: -0.2 (/) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: 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 [...] Content analysis details: (-0.2 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:635 listed in] [list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 SPF_NONE SPF: sender does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-mtd" Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org 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 Acked-by: Daniel Vetter --- 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);