github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-12 16:18:45 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

zram: drop pp_in_progress

Browse Source 
pp_in_progress makes sure that only one post-processing (writeback or
recomrpession) is active at any given time.  Functionality wise it,
basically, shadows zram init_lock, when init_lock is acquired in writer
mode.

Switch recompress_store() and writeback_store() to take zram init_lock in
writer mode, like all store() sysfs handlers should do, so that we can
drop pp_in_progress.  Recompression and writeback can be somewhat slow, so
holding init_lock in writer mode can block zram attrs reads, but in
reality the only zram attrs reads that take place are mm_stat reads, and
usually it's the same process that reads mm_stat and does recompression or
writeback.

Link: https://lkml.kernel.org/r/20251216071342.687993-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sergey Senozhatsky 2025-12-16 16:13:42 +09:00 committed by Andrew Morton
parent 9082f24bd3
commit 657a81fe3b
2 changed files with 8 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/block/zram/zram_drv.c
View File

@ -902,7 +902,7 @@ static struct zram_wb_ctl *init_wb_ctl(struct zram *zram)
static void zram_account_writeback_rollback(struct zram *zram)
{
lockdep_assert_held_read(&zram->init_lock);
lockdep_assert_held_write(&zram->init_lock);
if (zram->wb_limit_enable)
zram->bd_wb_limit += 1UL << (PAGE_SHIFT - 12);
@ -910,7 +910,7 @@ static void zram_account_writeback_rollback(struct zram *zram)
static void zram_account_writeback_submit(struct zram *zram)
{
lockdep_assert_held_read(&zram->init_lock);
lockdep_assert_held_write(&zram->init_lock);
if (zram->wb_limit_enable && zram->bd_wb_limit > 0)
zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12);
@ -1264,24 +1264,16 @@ static ssize_t writeback_store(struct device *dev,
ssize_t ret = len;
int err, mode = 0;
guard(rwsem_read)(&zram->init_lock);
guard(rwsem_write)(&zram->init_lock);
if (!init_done(zram))
return -EINVAL;
/* Do not permit concurrent post-processing actions. */
if (atomic_xchg(&zram->pp_in_progress, 1))
return -EAGAIN;
if (!zram->backing_dev) {
ret = -ENODEV;
goto out;
}
if (!zram->backing_dev)
return -ENODEV;
pp_ctl = init_pp_ctl();
if (!pp_ctl) {
ret = -ENOMEM;
goto out;
}
if (!pp_ctl)
return -ENOMEM;
wb_ctl = init_wb_ctl(zram);
if (!wb_ctl) {
@ -1358,7 +1350,6 @@ static ssize_t writeback_store(struct device *dev,
out:
release_pp_ctl(zram, pp_ctl);
release_wb_ctl(wb_ctl);
atomic_set(&zram->pp_in_progress, 0);
return ret;
}
@ -2619,14 +2610,10 @@ static ssize_t recompress_store(struct device *dev,
if (threshold >= huge_class_size)
return -EINVAL;
guard(rwsem_read)(&zram->init_lock);
guard(rwsem_write)(&zram->init_lock);
if (!init_done(zram))
return -EINVAL;
/* Do not permit concurrent post-processing actions. */
if (atomic_xchg(&zram->pp_in_progress, 1))
return -EAGAIN;
if (algo) {
bool found = false;
@ -2697,7 +2684,6 @@ static ssize_t recompress_store(struct device *dev,
if (page)
__free_page(page);
release_pp_ctl(zram, ctl);
atomic_set(&zram->pp_in_progress, 0);
return ret;
}
#endif
@ -2888,7 +2874,6 @@ static void zram_reset_device(struct zram *zram)
zram->disksize = 0;
zram_destroy_comps(zram);
memset(&zram->stats, 0, sizeof(zram->stats));
atomic_set(&zram->pp_in_progress, 0);
reset_bdev(zram);
comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
@ -3124,7 +3109,6 @@ static int zram_add(void)
zram->disk->fops = &zram_devops;
zram->disk->private_data = zram;
snprintf(zram->disk->disk_name, 16, "zram%d", device_id);
atomic_set(&zram->pp_in_progress, 0);
zram_comp_params_reset(zram);
comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);

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

@ -143,6 +143,5 @@ struct zram {
#ifdef CONFIG_ZRAM_MEMORY_TRACKING
struct dentry *debugfs_dir;
#endif
atomic_t pp_in_progress;
};
#endif