6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sergey Senozhatsky [ Upstream commit a4f506c569e1320c2db4a32955e47961fcf02b05 ] 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. Link: https://lkml.kernel.org/r/20251122074029.3948921-5-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky Reviewed-by: Brian Geffon Cc: Minchan Kim Cc: Richard Chang Cc: Yuwen Chen Signed-off-by: Andrew Morton Stable-dep-of: dde75313eed0 ("zram: set default primary compressor in zram_destroy_comps()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/block/zram/zram_drv.c | 23 ++++------------------- drivers/block/zram/zram_drv.h | 1 - 2 files changed, 4 insertions(+), 20 deletions(-) --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -512,9 +512,7 @@ static ssize_t writeback_limit_enable_st 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_sh 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(str 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(str } 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); @@ -747,18 +739,17 @@ static int zram_writeback_slots(struct z int ret = 0, err; u32 index; + lockdep_assert_held_read(&zram->init_lock); + page = alloc_page(GFP_KERNEL); if (!page) return -ENOMEM; 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); if (!blk_idx) { blk_idx = alloc_block_bdev(zram); @@ -824,10 +815,8 @@ static int zram_writeback_slots(struct z zram_set_handle(zram, index, blk_idx); blk_idx = 0; atomic64_inc(&zram->stats.pages_stored); - spin_lock(&zram->wb_limit_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); next: zram_slot_unlock(zram, index); release_pp_slot(zram, pps); @@ -2469,7 +2458,7 @@ static void zram_destroy_comps(struct zr static void zram_reset_device(struct zram *zram) { - down_write(&zram->init_lock); + guard(rwsem_write)(&zram->init_lock); zram->limit_pages = 0; @@ -2485,7 +2474,6 @@ static void zram_reset_device(struct zra reset_bdev(zram); comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor); - up_write(&zram->init_lock); } static ssize_t disksize_store(struct device *dev, @@ -2697,9 +2685,6 @@ static int zram_add(void) device_id = ret; init_rwsem(&zram->init_lock); -#ifdef CONFIG_ZRAM_WRITEBACK - spin_lock_init(&zram->wb_limit_lock); -#endif /* gendisk structure */ zram->disk = blk_alloc_disk(&lim, NUMA_NO_NODE); --- 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; u64 bd_wb_limit; struct block_device *bdev;