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zram: Replace bit spinlocks with a spinlock_t.

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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 <umgwanakikbuti@gmail.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20240906141520.730009-2-bigeasy@linutronix.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Mike Galbraith 2024-09-06 16:14:43 +02:00 committed by Jens Axboe
parent 296dbc72d2
commit 9518e5bfaa
2 changed files with 15 additions and 4 deletions
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18
drivers/block/zram/zram_drv.c
View File

@ -59,17 +59,24 @@ static int zram_read_page(struct zram *zram, struct page *page, u32 index,
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)
@ -1211,7 +1218,7 @@ static void zram_meta_free(struct zram *zram, u64 disksize)
static bool zram_meta_alloc(struct zram *zram, u64 disksize)
{
size_t num_pages;
size_t num_pages, index;
num_pages = disksize >> PAGE_SHIFT;
zram->table = vzalloc(array_size(num_pages, sizeof(*zram->table)));
@ -1226,6 +1233,9 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
if (!huge_class_size)
huge_class_size = zs_huge_class_size(zram->mem_pool);
for (index = 0; index < num_pages; index++)
spin_lock_init(&zram->table[index].lock);
return true;
}

1
drivers/block/zram/zram_drv.h
View File

@ -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