From: Mike Galbraith Date: Thu, 31 Mar 2016 04:08:28 +0200 Subject: [PATCH 1/3] zram: Replace bit spinlocks with a spinlock_t. Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.10/older/patches-6.10.2-rt14.tar.xz The bit spinlock disables preemption. The spinlock_t lock becomes a sleeping lock on PREEMPT_RT and it can not be acquired in this context. In this locked section, zs_free() acquires a zs_pool::lock, and there is access to zram::wb_limit_lock. Add a spinlock_t for locking. Keep the set/ clear ZRAM_LOCK bit after the lock has been acquired/ dropped. The size of struct zram_table_entry increases by 4 bytes due to lock and additional 4 bytes padding with CONFIG_ZRAM_TRACK_ENTRY_ACTIME enabled. Signed-off-by: Mike Galbraith Link: https://lore.kernel.org/r/20240620153556.777272-2-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior Link: https://lkml.kernel.org/r/YqIbMuHCPiQk+Ac2@linutronix.de Link: https://lore.kernel.org/20230323161830.jFbWCosd@linutronix.de Link: https://lore.kernel.org/20240619150814.BRAvaziM@linutronix.de --- drivers/block/zram/zram_drv.c | 22 +++++++++++++++++++--- drivers/block/zram/zram_drv.h | 1 + 2 files changed, 20 insertions(+), 3 deletions(-) --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -57,19 +57,34 @@ static void zram_free_page(struct zram * static int zram_read_page(struct zram *zram, struct page *page, u32 index, struct bio *parent); +static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages) +{ + size_t index; + + for (index = 0; index < num_pages; index++) + spin_lock_init(&zram->table[index].lock); +} + static int zram_slot_trylock(struct zram *zram, u32 index) { - return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags); + int ret; + + ret = spin_trylock(&zram->table[index].lock); + if (ret) + __set_bit(ZRAM_LOCK, &zram->table[index].flags); + return ret; } static void zram_slot_lock(struct zram *zram, u32 index) { - bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags); + spin_lock(&zram->table[index].lock); + __set_bit(ZRAM_LOCK, &zram->table[index].flags); } static void zram_slot_unlock(struct zram *zram, u32 index) { - bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags); + __clear_bit(ZRAM_LOCK, &zram->table[index].flags); + spin_unlock(&zram->table[index].lock); } static inline bool init_done(struct zram *zram) @@ -1226,6 +1241,7 @@ static bool zram_meta_alloc(struct zram if (!huge_class_size) huge_class_size = zs_huge_class_size(zram->mem_pool); + zram_meta_init_table_locks(zram, num_pages); return true; } --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -69,6 +69,7 @@ struct zram_table_entry { unsigned long element; }; unsigned long flags; + spinlock_t lock; #ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME ktime_t ac_time; #endif