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Fri, 21 Nov 2025 23:40:58 -0800 (PST) Received: from tigerii.tok.corp.google.com ([2a00:79e0:2031:6:948e:149d:963b:f660]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b138628sm77771555ad.31.2025.11.21.23.40.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Nov 2025 23:40:58 -0800 (PST) From: Sergey Senozhatsky To: Andrew Morton , Minchan Kim , Yuwen Chen , Richard Chang Cc: Brian Geffon , Fengyu Lian , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, Sergey Senozhatsky Subject: [PATCHv6 4/6] zram: drop wb_limit_lock Date: Sat, 22 Nov 2025 16:40:27 +0900 Message-ID: <20251122074029.3948921-5-senozhatsky@chromium.org> X-Mailer: git-send-email 2.52.0.460.gd25c4c69ec-goog In-Reply-To: <20251122074029.3948921-1-senozhatsky@chromium.org> References: <20251122074029.3948921-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: A03DA40003 X-Stat-Signature: k9pk1mbokyb61nqc9wnd4pqzkcpk6geo X-HE-Tag: 1763797259-612143 X-HE-Meta: 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 cJt+Hhhb 1KdRGNjRWmGLOe6LF4kz8ymY87of4Zqgu8Jdkw1qkt0lzMcBCgx9R8RvPH7v2lVHeavvYVMF5U3Oy9lBxNa6KNkJIXaHaIh+2JukR57oBT3Rfl9boQVADN6Od/WV6lTvn3Kl9yCwUCTglaPKn5wdar+jVFonI52Cl/DYFmE2PgtZ0lMJeruIuJv8tAFDhmWFdDrsZ1ZrNV7w3YbCMSsCBGqPzrD7xaUeHjpJJsb6xZFhWjjE1FGA3NPiUCeRz3F+EfEuMgBlXAYwcDOvVUcBDKH7EdyF9CQXoXnhLvqPULmBI/CY/pzS5XTOFxvnj1qzbP/Z4yKUVwK9HHm4u//EK3Xa27G/tt9JX4IUIUV4O/EP9W2P2QtQ4XCn7tA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: We don't need wb_limit_lock. Writeback limit setters take an exclusive write zram init_lock, while wb_limit modifications happen only from a single task and under zram read init_lock. No concurrent wb_limit modifications are possible (we permit only one post-processing task at a time). Add lockdep assertions to wb_limit mutators. While at it, fixup coding styles. Signed-off-by: Sergey Senozhatsky Reviewed-by: Brian Geffon --- drivers/block/zram/zram_drv.c | 22 +++++----------------- drivers/block/zram/zram_drv.h | 1 - 2 files changed, 5 insertions(+), 18 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 8dd733707a40..806497225603 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -532,9 +532,7 @@ static ssize_t writeback_limit_enable_store(struct device *dev, return ret; down_write(&zram->init_lock); - spin_lock(&zram->wb_limit_lock); zram->wb_limit_enable = val; - spin_unlock(&zram->wb_limit_lock); up_write(&zram->init_lock); ret = len; @@ -549,9 +547,7 @@ static ssize_t writeback_limit_enable_show(struct device *dev, struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); - spin_lock(&zram->wb_limit_lock); val = zram->wb_limit_enable; - spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); return sysfs_emit(buf, "%d\n", val); @@ -569,9 +565,7 @@ static ssize_t writeback_limit_store(struct device *dev, return ret; down_write(&zram->init_lock); - spin_lock(&zram->wb_limit_lock); zram->bd_wb_limit = val; - spin_unlock(&zram->wb_limit_lock); up_write(&zram->init_lock); ret = len; @@ -579,15 +573,13 @@ static ssize_t writeback_limit_store(struct device *dev, } static ssize_t writeback_limit_show(struct device *dev, - struct device_attribute *attr, char *buf) + struct device_attribute *attr, char *buf) { u64 val; struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); - spin_lock(&zram->wb_limit_lock); val = zram->bd_wb_limit; - spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); return sysfs_emit(buf, "%llu\n", val); @@ -869,18 +861,18 @@ static struct zram_wb_ctl *init_wb_ctl(struct zram *zram) static void zram_account_writeback_rollback(struct zram *zram) { - spin_lock(&zram->wb_limit_lock); + lockdep_assert_held_read(&zram->init_lock); + if (zram->wb_limit_enable) zram->bd_wb_limit += 1UL << (PAGE_SHIFT - 12); - spin_unlock(&zram->wb_limit_lock); } static void zram_account_writeback_submit(struct zram *zram) { - spin_lock(&zram->wb_limit_lock); + lockdep_assert_held_read(&zram->init_lock); + if (zram->wb_limit_enable && zram->bd_wb_limit > 0) zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12); - spin_unlock(&zram->wb_limit_lock); } static int zram_writeback_complete(struct zram *zram, struct zram_wb_req *req) @@ -1005,13 +997,10 @@ static int zram_writeback_slots(struct zram *zram, u32 index = 0; while ((pps = select_pp_slot(ctl))) { - spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && !zram->bd_wb_limit) { - spin_unlock(&zram->wb_limit_lock); ret = -EIO; break; } - spin_unlock(&zram->wb_limit_lock); while (!req) { req = zram_select_idle_req(wb_ctl); @@ -2962,7 +2951,6 @@ static int zram_add(void) init_rwsem(&zram->init_lock); #ifdef CONFIG_ZRAM_WRITEBACK zram->wb_batch_size = 32; - spin_lock_init(&zram->wb_limit_lock); #endif /* gendisk structure */ diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 1a647f42c1a4..c6d94501376c 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -127,7 +127,6 @@ struct zram { bool claim; /* Protected by disk->open_mutex */ #ifdef CONFIG_ZRAM_WRITEBACK struct file *backing_dev; - spinlock_t wb_limit_lock; bool wb_limit_enable; u32 wb_batch_size; u64 bd_wb_limit; -- 2.52.0.460.gd25c4c69ec-goog