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Thu, 13 Nov 2025 00:54:33 -0800 (PST) Received: from tigerii.tok.corp.google.com ([2401:fa00:8f:203:6d96:d8c6:55e6:2377]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2985c2346f3sm17486465ad.18.2025.11.13.00.54.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Nov 2025 00:54:32 -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: [PATCHv2 4/4] zram: drop wb_limit_lock Date: Thu, 13 Nov 2025 17:54:02 +0900 Message-ID: <20251113085402.1811522-5-senozhatsky@chromium.org> X-Mailer: git-send-email 2.51.2.1041.gc1ab5b90ca-goog In-Reply-To: <20251113085402.1811522-1-senozhatsky@chromium.org> References: <20251113085402.1811522-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 6D33720008 X-Rspamd-Server: rspam07 X-Stat-Signature: d3tdyms1hqdrz8mpsyg9kpya31enya74 X-Rspam-User: X-HE-Tag: 1763024074-272494 X-HE-Meta: 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 Nbe4AVfN 5C7h2T/K422uNDXk2gzL/xgM0IxzD6uFj5lEmQZ3l827hzQbCil6Eok6sOa+GvmDNXIkurIMNBFXO42+va6/Ou/G3IeZ9JoTIvZkZjBbt6p7hw8MzLP3H21kC6QfMYPikTmuLigF/azGv90H/+3H4b7aCls31LBFVNLj2oyeUxcF0GsSB8UiQ6lAZa6ztPzx9f1cbH/8wsY4TqFi5FMh7YZih+4fTVUpNSbtDVRuuc/7DwaLzFdueTQfwngG5KN8jSn9LWXn5jLY0XTNxYlrcMTcqWCU5nwz5jQcjMZSAYBhv/GqMlgkwypBMYP3Q9PirRETOw/J0JlcG+2ELZuLqRS9+XN/w+9m2eA/Z 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 --- 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 6312b0437618..28afb010307d 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -512,9 +512,7 @@ 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; @@ -529,9 +527,7 @@ 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); @@ -549,9 +545,7 @@ 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; @@ -559,15 +553,13 @@ 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); @@ -866,18 +858,18 @@ 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) @@ -991,13 +983,10 @@ static int zram_writeback_slots(struct zram *zram, blk_start_plug(&wb_ctl->plug); 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 = select_idle_req(wb_ctl); @@ -2944,7 +2933,6 @@ static int zram_add(void) init_rwsem(&zram->init_lock); #ifdef CONFIG_ZRAM_WRITEBACK zram->wb_batch_size = 1; - 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; -- 2.51.2.1041.gc1ab5b90ca-goog