From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 7ac07a26dea79c3892436bce41cce03dcbd3c4c7 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Patch series "zram: Support multiple compression streams", v5.

This series adds support for multiple compression streams. The main idea is that different compression algorithms have different characteristics and zram may benefit when it uses a combination of algorithms: a default algorithm that is faster but have lower compression rate and a secondary algorithm that can use higher compression rate at a price of slower compression/decompression.

There are several use-case for this functionality:

- huge pages re-compression: zstd or deflate can successfully compress huge pages (~50% of huge pages on my synthetic ChromeOS tests), IOW pages that lzo was not able to compress.

- idle pages re-compression: idle/cold pages sit in the memory and we may reduce zsmalloc memory usage if we recompress those idle pages.

Userspace has a number of ways to control the behavior and impact of zram recompression: what type of pages should be recompressed, size watermarks, etc. Please refer to documentation patch.

This patch (of 13):

The patch turns compression streams and compressor algorithm name struct zram members into arrays, so that we can have multiple compression streams support (in the next patches).

The patch uses a rather explicit API for compressor selection:

- Get primary (default) compression stream zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]) - Get secondary compression stream zcomp_stream_get(zram->comps[ZRAM_SECONDARY_COMP])

We use similar API for compression streams put().

At this point we always have just one compression stream, since CONFIG_ZRAM_MULTI_COMP is not yet defined.

Link: https://lkml.kernel.org/r/20221109115047.2921851-1-senozhatsky@chromium.org Link: https://lkml.kernel.org/r/20221109115047.2921851-2-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Minchan Kim minchan@kernel.org Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Cc: Nhat Pham nphamcs@gmail.com Cc: Alexey Romanov avromanov@sberdevices.ru Signed-off-by: Andrew Morton akpm@linux-foundation.org

Conflicts: drivers/block/zram/zram_drv.c

Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/block/zram/zcomp.c | 6 +-- drivers/block/zram/zcomp.h | 2 +- drivers/block/zram/zram_drv.c | 89 +++++++++++++++++++++++++---------- drivers/block/zram/zram_drv.h | 14 +++++- 4 files changed, 79 insertions(+), 32 deletions(-)

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index b08650417bf0..d934a0d9b922 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -204,7 +204,7 @@ void zcomp_destroy(struct zcomp *comp) * case of allocation error, or any other error potentially * returned by zcomp_init(). */ -struct zcomp *zcomp_create(const char *compress) +struct zcomp *zcomp_create(const char *alg) { struct zcomp *comp; int error; @@ -214,14 +214,14 @@ struct zcomp *zcomp_create(const char *compress) * is not loaded yet. We must do it here, otherwise we are about to * call /sbin/modprobe under CPU hot-plug lock. */ - if (!zcomp_available_algorithm(compress)) + if (!zcomp_available_algorithm(alg)) return ERR_PTR(-EINVAL);

comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL); if (!comp) return ERR_PTR(-ENOMEM);

- comp->name = compress; + comp->name = alg; error = zcomp_init(comp); if (error) { kfree(comp); diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h index 40f6420f4b2e..cdefdef93da8 100644 --- a/drivers/block/zram/zcomp.h +++ b/drivers/block/zram/zcomp.h @@ -27,7 +27,7 @@ int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node); ssize_t zcomp_available_show(const char *comp, char *buf); bool zcomp_available_algorithm(const char *comp);

-struct zcomp *zcomp_create(const char *comp); +struct zcomp *zcomp_create(const char *alg); void zcomp_destroy(struct zcomp *comp);

struct zcomp_strm *zcomp_stream_get(struct zcomp *comp); diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 56074ac5bd12..cb704ce6c24d 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -986,36 +986,53 @@ static ssize_t comp_algorithm_show(struct device *dev, struct zram *zram = dev_to_zram(dev);

down_read(&zram->init_lock); - sz = zcomp_available_show(zram->compressor, buf); + sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_COMP], buf); up_read(&zram->init_lock);

return sz; }

+static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg) +{ + /* Do not kfree() algs that we didn't allocate, IOW the default ones */ + if (zram->comp_algs[prio] != default_compressor) + kfree(zram->comp_algs[prio]); + zram->comp_algs[prio] = alg; +} + static ssize_t comp_algorithm_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { struct zram *zram = dev_to_zram(dev); - char compressor[ARRAY_SIZE(zram->compressor)]; + char *compressor; size_t sz;

- strlcpy(compressor, buf, sizeof(compressor)); + sz = strlen(buf); + if (sz >= CRYPTO_MAX_ALG_NAME) + return -E2BIG; + + compressor = kstrdup(buf, GFP_KERNEL); + if (!compressor) + return -ENOMEM; + /* ignore trailing newline */ - sz = strlen(compressor); if (sz > 0 && compressor[sz - 1] == '\n') compressor[sz - 1] = 0x00;

- if (!zcomp_available_algorithm(compressor)) + if (!zcomp_available_algorithm(compressor)) { + kfree(compressor); return -EINVAL; + }

down_write(&zram->init_lock); if (init_done(zram)) { up_write(&zram->init_lock); + kfree(compressor); pr_info("Can't change algorithm for initialized device\n"); return -EBUSY; }

- strcpy(zram->compressor, compressor); + comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, compressor); up_write(&zram->init_lock); return len; } @@ -1259,7 +1276,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, size = zram_get_obj_size(zram, index);

if (size != PAGE_SIZE) - zstrm = zcomp_stream_get(zram->comp); + zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]);

src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) { @@ -1271,7 +1288,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, dst = kmap_atomic(page); ret = zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst); - zcomp_stream_put(zram->comp); + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); } zs_unmap_object(zram->mem_pool, handle); zram_slot_unlock(zram, index); @@ -1340,13 +1357,13 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, kunmap_atomic(mem);

compress_again: - zstrm = zcomp_stream_get(zram->comp); + zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]); src = kmap_atomic(page); ret = zcomp_compress(zstrm, src, &comp_len); kunmap_atomic(src);

if (unlikely(ret)) { - zcomp_stream_put(zram->comp); + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); pr_err("Compression failed! err=%d\n", ret); zs_free(zram->mem_pool, handle); return ret; @@ -1374,7 +1391,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, __GFP_HIGHMEM | __GFP_MOVABLE); if (!handle) { - zcomp_stream_put(zram->comp); + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); atomic64_inc(&zram->stats.writestall); handle = zs_malloc(zram->mem_pool, comp_len, GFP_NOIO | __GFP_HIGHMEM | @@ -1388,7 +1405,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, update_used_max(zram, alloced_pages);

if (zram->limit_pages && alloced_pages > zram->limit_pages) { - zcomp_stream_put(zram->comp); + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); zs_free(zram->mem_pool, handle); return -ENOMEM; } @@ -1402,7 +1419,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec, if (comp_len == PAGE_SIZE) kunmap_atomic(src);

- zcomp_stream_put(zram->comp); + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); zs_unmap_object(zram->mem_pool, handle); atomic64_add(comp_len, &zram->stats.compr_data_size); out: @@ -1682,9 +1699,22 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, return ret; }

+static void zram_destroy_comps(struct zram *zram) +{ + u32 prio; + + for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) { + struct zcomp *comp = zram->comps[prio]; + + zram->comps[prio] = NULL; + if (!comp) + continue; + zcomp_destroy(comp); + } +} + static void zram_reset_device(struct zram *zram) { - struct zcomp *comp; u64 disksize;

down_write(&zram->init_lock); @@ -1696,7 +1726,6 @@ static void zram_reset_device(struct zram *zram) return; }

- comp = zram->comp; disksize = zram->disksize; zram->disksize = 0;

@@ -1705,10 +1734,11 @@ static void zram_reset_device(struct zram *zram)

/* I/O operation under all of CPU are done so let's free */ zram_meta_free(zram, disksize); + zram_destroy_comps(zram); memset(&zram->stats, 0, sizeof(zram->stats)); - zcomp_destroy(comp); reset_bdev(zram);

+ comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor); up_write(&zram->init_lock); }

@@ -1719,6 +1749,7 @@ static ssize_t disksize_store(struct device *dev, struct zcomp *comp; struct zram *zram = dev_to_zram(dev); int err; + u32 prio;

disksize = memparse(buf, NULL); if (!disksize) @@ -1737,15 +1768,20 @@ static ssize_t disksize_store(struct device *dev, goto out_unlock; }

- comp = zcomp_create(zram->compressor); - if (IS_ERR(comp)) { - pr_err("Cannot initialise %s compressing backend\n", - zram->compressor); - err = PTR_ERR(comp); - goto out_free_meta; - } + for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) { + if (!zram->comp_algs[prio]) + continue;

- zram->comp = comp; + comp = zcomp_create(zram->comp_algs[prio]); + if (IS_ERR(comp)) { + pr_err("Cannot initialise %s compressing backend\n", + zram->comp_algs[prio]); + err = PTR_ERR(comp); + goto out_free_comps; + } + + zram->comps[prio] = comp; + } zram->disksize = disksize; set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);

@@ -1754,7 +1790,8 @@ static ssize_t disksize_store(struct device *dev,

return len;

-out_free_meta: +out_free_comps: + zram_destroy_comps(zram); zram_meta_free(zram, disksize); out_unlock: up_write(&zram->init_lock); @@ -1966,7 +2003,7 @@ static int zram_add(void) blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue); device_add_disk(NULL, zram->disk, zram_disk_attr_groups);

- strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); + zram->comp_algs[ZRAM_PRIMARY_COMP] = default_compressor;

zram_debugfs_register(zram); pr_info("Added device: %s\n", zram->disk->disk_name); diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index f2fd46daa760..a3fcd6b21091 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -89,10 +89,20 @@ struct zram_stats { #endif };

+#ifdef CONFIG_ZRAM_MULTI_COMP +#define ZRAM_PRIMARY_COMP 0U +#define ZRAM_SECONDARY_COMP 1U +#define ZRAM_MAX_COMPS 4U +#else +#define ZRAM_PRIMARY_COMP 0U +#define ZRAM_SECONDARY_COMP 0U +#define ZRAM_MAX_COMPS 1U +#endif + struct zram { struct zram_table_entry *table; struct zs_pool *mem_pool; - struct zcomp *comp; + struct zcomp *comps[ZRAM_MAX_COMPS]; struct gendisk *disk; /* Prevent concurrent execution of device init */ struct rw_semaphore init_lock; @@ -107,7 +117,7 @@ struct zram { * we can store in a disk. */ u64 disksize; /* bytes */ - char compressor[CRYPTO_MAX_ALG_NAME]; + const char *comp_algs[ZRAM_MAX_COMPS]; /* * zram is claimed so open request will be failed */

From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 001d9273570115b2eb360d5452bbc46f6cc063a1 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Introduce recomp_algorithm sysfs knob that controls secondary algorithm selection used for recompression.

We will support up to 3 secondary compression algorithms which are sorted in order of their priority. To select an algorithm user has to provide its name and priority:

echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm

During recompression zram iterates through the list of registered secondary algorithms in order of their priorities.

We also have a short version for cases when there is only one secondary compression algorithm:

echo "algo=zstd" > /sys/block/zramX/recomp_algorithm

This will register zstd as the secondary algorithm with priority 1.

Link: https://lkml.kernel.org/r/20221109115047.2921851-3-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org

Conflicts: drivers/block/zram/zram_drv.c

Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/block/zram/zram_drv.c | 124 ++++++++++++++++++++++++++++------ 1 file changed, 105 insertions(+), 19 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index cb704ce6c24d..369b24f871ce 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -979,31 +979,28 @@ static ssize_t max_comp_streams_store(struct device *dev, return len; }

-static ssize_t comp_algorithm_show(struct device *dev, - struct device_attribute *attr, char *buf) +static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg) { - size_t sz; - struct zram *zram = dev_to_zram(dev); + /* Do not free statically defined compression algorithms */ + if (zram->comp_algs[prio] != default_compressor) + kfree(zram->comp_algs[prio]); + + zram->comp_algs[prio] = alg; +} + +static ssize_t __comp_algorithm_show(struct zram *zram, u32 prio, char *buf) +{ + ssize_t sz;

down_read(&zram->init_lock); - sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_COMP], buf); + sz = zcomp_available_show(zram->comp_algs[prio], buf); up_read(&zram->init_lock);

return sz; }

-static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg) -{ - /* Do not kfree() algs that we didn't allocate, IOW the default ones */ - if (zram->comp_algs[prio] != default_compressor) - kfree(zram->comp_algs[prio]); - zram->comp_algs[prio] = alg; -} - -static ssize_t comp_algorithm_store(struct device *dev, - struct device_attribute *attr, const char *buf, size_t len) +static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf) { - struct zram *zram = dev_to_zram(dev); char *compressor; size_t sz;

@@ -1032,10 +1029,93 @@ static ssize_t comp_algorithm_store(struct device *dev, return -EBUSY; }

- comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, compressor); + comp_algorithm_set(zram, prio, compressor); up_write(&zram->init_lock); - return len; + return 0; +} + +static ssize_t comp_algorithm_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct zram *zram = dev_to_zram(dev); + + return __comp_algorithm_show(zram, ZRAM_PRIMARY_COMP, buf); +} + +static ssize_t comp_algorithm_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct zram *zram = dev_to_zram(dev); + int ret; + + ret = __comp_algorithm_store(zram, ZRAM_PRIMARY_COMP, buf); + return ret ? ret : len; +} + +#ifdef CONFIG_ZRAM_MULTI_COMP +static ssize_t recomp_algorithm_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct zram *zram = dev_to_zram(dev); + ssize_t sz = 0; + u32 prio; + + for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) { + if (!zram->comp_algs[prio]) + continue; + + sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2, "#%d: ", prio); + sz += __comp_algorithm_show(zram, prio, buf + sz); + } + + return sz; +} + +static ssize_t recomp_algorithm_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t len) +{ + struct zram *zram = dev_to_zram(dev); + int prio = ZRAM_SECONDARY_COMP; + char *args, *param, *val; + char *alg = NULL; + int ret; + + args = skip_spaces(buf); + while (*args) { + args = next_arg(args, &param, &val); + + if (!*val) + return -EINVAL; + + if (!strcmp(param, "algo")) { + alg = val; + continue; + } + + if (!strcmp(param, "priority")) { + ret = kstrtoint(val, 10, &prio); + if (ret) + return ret; + continue; + } + } + + if (!alg) + return -EINVAL; + + if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) + return -EINVAL; + + ret = __comp_algorithm_store(zram, prio, alg); + return ret ? ret : len; } +#endif

static ssize_t compact_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) @@ -1888,6 +1968,9 @@ static DEVICE_ATTR_WO(writeback); static DEVICE_ATTR_RW(writeback_limit); static DEVICE_ATTR_RW(writeback_limit_enable); #endif +#ifdef CONFIG_ZRAM_MULTI_COMP +static DEVICE_ATTR_RW(recomp_algorithm); +#endif

static struct attribute *zram_disk_attrs[] = { &dev_attr_disksize.attr, @@ -1911,6 +1994,9 @@ static struct attribute *zram_disk_attrs[] = { &dev_attr_bd_stat.attr, #endif &dev_attr_debug_stat.attr, +#ifdef CONFIG_ZRAM_MULTI_COMP + &dev_attr_recomp_algorithm.attr, +#endif NULL, };

@@ -2003,7 +2089,7 @@ static int zram_add(void) blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES, zram->disk->queue); device_add_disk(NULL, zram->disk, zram_disk_attr_groups);

- zram->comp_algs[ZRAM_PRIMARY_COMP] = default_compressor; + comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);

zram_debugfs_register(zram); pr_info("Added device: %s\n", zram->disk->disk_name);

From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 84b33bf7888975d28c0e57011b75c445279c60ec category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Allow zram to recompress (using secondary compression streams) pages.

Re-compression algorithms (we support up to 3 at this stage) are selected via recomp_algorithm:

echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm

Please read documentation for more details.

We support several recompression modes:

1) IDLE pages recompression is activated by `idle` mode

echo "type=idle" > /sys/block/zram0/recompress

2) Since there may be many idle pages user-space may pass a size threshold value (in bytes) and we will recompress pages only of equal or greater size:

echo "threshold=888" > /sys/block/zram0/recompress

3) HUGE pages recompression is activated by `huge` mode

echo "type=huge" > /sys/block/zram0/recompress

4) HUGE_IDLE pages recompression is activated by `huge_idle` mode

echo "type=huge_idle" > /sys/block/zram0/recompress

[senozhatsky@chromium.org: we should always zero out err variable in recompress loop[ Link: https://lkml.kernel.org/r/20221110143423.3250790-1-senozhatsky@chromium.org Link: https://lkml.kernel.org/r/20221109115047.2921851-5-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Nathan Chancellor nathan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org

Conflicts: drivers/block/zram/zram_drv.h

Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/block/zram/Kconfig | 9 ++ drivers/block/zram/zram_drv.c | 264 +++++++++++++++++++++++++++++++++- drivers/block/zram/zram_drv.h | 7 + 3 files changed, 277 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig index fe7a4b7d30cf..a23139b7e9c5 100644 --- a/drivers/block/zram/Kconfig +++ b/drivers/block/zram/Kconfig @@ -37,3 +37,12 @@ config ZRAM_MEMORY_TRACKING /sys/kernel/debug/zram/zramX/block_state.

See Documentation/admin-guide/blockdev/zram.rst for more information. + +config ZRAM_MULTI_COMP + bool "Enable multiple compression streams" + depends on ZRAM + help + This will enable multi-compression streams, so that ZRAM can + re-compress pages using a potentially slower but more effective + compression algorithm. Note, that IDLE page recompression + requires ZRAM_MEMORY_TRACKING. diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 4ebd60a1ae37..2535702add00 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -157,6 +157,25 @@ static inline bool is_partial_io(struct bio_vec *bvec) } #endif

+static inline void zram_set_priority(struct zram *zram, u32 index, u32 prio) +{ + prio &= ZRAM_COMP_PRIORITY_MASK; + /* + * Clear previous priority value first, in case if we recompress + * further an already recompressed page + */ + zram->table[index].flags &= ~(ZRAM_COMP_PRIORITY_MASK << + ZRAM_COMP_PRIORITY_BIT1); + zram->table[index].flags |= (prio << ZRAM_COMP_PRIORITY_BIT1); +} + +static inline u32 zram_get_priority(struct zram *zram, u32 index) +{ + u32 prio = zram->table[index].flags >> ZRAM_COMP_PRIORITY_BIT1; + + return prio & ZRAM_COMP_PRIORITY_MASK; +} + /* * Check if request is within bounds and aligned on zram logical blocks. */ @@ -1285,6 +1304,11 @@ static void zram_free_page(struct zram *zram, size_t index) atomic64_dec(&zram->stats.huge_pages); }

+ if (zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE)) + zram_clear_flag(zram, index, ZRAM_INCOMPRESSIBLE); + + zram_set_priority(zram, index, 0); + if (zram_test_flag(zram, index, ZRAM_WB)) { zram_clear_flag(zram, index, ZRAM_WB); free_block_bdev(zram, zram_get_element(zram, index)); @@ -1345,6 +1369,7 @@ static int zram_read_from_zspool(struct zram *zram, struct page *page, unsigned long handle; unsigned int size; void *src, *dst; + u32 prio; int ret;

handle = zram_get_handle(zram, index); @@ -1361,8 +1386,10 @@ static int zram_read_from_zspool(struct zram *zram, struct page *page,

size = zram_get_obj_size(zram, index);

- if (size != PAGE_SIZE) - zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]); + if (size != PAGE_SIZE) { + prio = zram_get_priority(zram, index); + zstrm = zcomp_stream_get(zram->comps[prio]); + }

src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) { @@ -1374,7 +1401,7 @@ static int zram_read_from_zspool(struct zram *zram, struct page *page, dst = kmap_atomic(page); ret = zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst); - zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]); + zcomp_stream_put(zram->comps[prio]); } zs_unmap_object(zram->mem_pool, handle); return ret; @@ -1599,6 +1626,235 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, return ret; }

+#ifdef CONFIG_ZRAM_MULTI_COMP +/* + * This function will decompress (unless it's ZRAM_HUGE) the page and then + * attempt to compress it using provided compression algorithm priority + * (which is potentially more effective). + * + * Corresponding ZRAM slot should be locked. + */ +static int zram_recompress(struct zram *zram, u32 index, struct page *page, + u32 threshold, u32 prio, u32 prio_max) +{ + struct zcomp_strm *zstrm = NULL; + unsigned long handle_old; + unsigned long handle_new; + unsigned int comp_len_old; + unsigned int comp_len_new; + void *src, *dst; + int ret; + + handle_old = zram_get_handle(zram, index); + if (!handle_old) + return -EINVAL; + + comp_len_old = zram_get_obj_size(zram, index); + /* + * Do not recompress objects that are already "small enough". + */ + if (comp_len_old < threshold) + return 0; + + ret = zram_read_from_zspool(zram, page, index); + if (ret) + return ret; + + /* + * Iterate the secondary comp algorithms list (in order of priority) + * and try to recompress the page. + */ + for (; prio < prio_max; prio++) { + if (!zram->comps[prio]) + continue; + + /* + * Skip if the object is already re-compressed with a higher + * priority algorithm (or same algorithm). + */ + if (prio <= zram_get_priority(zram, index)) + continue; + + zstrm = zcomp_stream_get(zram->comps[prio]); + src = kmap_atomic(page); + ret = zcomp_compress(zstrm, src, &comp_len_new); + kunmap_atomic(src); + + if (ret) { + zcomp_stream_put(zram->comps[prio]); + return ret; + } + + /* Continue until we make progress */ + if (comp_len_new >= huge_class_size || + comp_len_new >= comp_len_old || + (threshold && comp_len_new >= threshold)) { + zcomp_stream_put(zram->comps[prio]); + continue; + } + + /* Recompression was successful so break out */ + break; + } + + /* + * We did not try to recompress, e.g. when we have only one + * secondary algorithm and the page is already recompressed + * using that algorithm + */ + if (!zstrm) + return 0; + + /* + * All secondary algorithms failed to re-compress the page in a way + * that would save memory, mark the object as incompressible so that + * we will not try to compress it again. + */ + if (comp_len_new >= huge_class_size || comp_len_new >= comp_len_old) { + zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE); + return 0; + } + + /* Successful recompression but above threshold */ + if (threshold && comp_len_new >= threshold) + return 0; + + /* + * No direct reclaim (slow path) for handle allocation and no + * re-compression attempt (unlike in __zram_bvec_write()) since + * we already have stored that object in zsmalloc. If we cannot + * alloc memory for recompressed object then we bail out and + * simply keep the old (existing) object in zsmalloc. + */ + handle_new = zs_malloc(zram->mem_pool, comp_len_new, + __GFP_KSWAPD_RECLAIM | + __GFP_NOWARN | + __GFP_HIGHMEM | + __GFP_MOVABLE); + if (IS_ERR_VALUE(handle_new)) { + zcomp_stream_put(zram->comps[prio]); + return PTR_ERR((void *)handle_new); + } + + dst = zs_map_object(zram->mem_pool, handle_new, ZS_MM_WO); + memcpy(dst, zstrm->buffer, comp_len_new); + zcomp_stream_put(zram->comps[prio]); + + zs_unmap_object(zram->mem_pool, handle_new); + + zram_free_page(zram, index); + zram_set_handle(zram, index, handle_new); + zram_set_obj_size(zram, index, comp_len_new); + zram_set_priority(zram, index, prio); + + atomic64_add(comp_len_new, &zram->stats.compr_data_size); + atomic64_inc(&zram->stats.pages_stored); + + return 0; +} + +#define RECOMPRESS_IDLE (1 << 0) +#define RECOMPRESS_HUGE (1 << 1) + +static ssize_t recompress_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + u32 mode = 0, threshold = 0, prio = ZRAM_SECONDARY_COMP; + unsigned long nr_pages = zram->disksize >> PAGE_SHIFT; + char *args, *param, *val; + unsigned long index; + struct page *page; + ssize_t ret; + + args = skip_spaces(buf); + while (*args) { + args = next_arg(args, &param, &val); + + if (!*val) + return -EINVAL; + + if (!strcmp(param, "type")) { + if (!strcmp(val, "idle")) + mode = RECOMPRESS_IDLE; + if (!strcmp(val, "huge")) + mode = RECOMPRESS_HUGE; + if (!strcmp(val, "huge_idle")) + mode = RECOMPRESS_IDLE | RECOMPRESS_HUGE; + continue; + } + + if (!strcmp(param, "threshold")) { + /* + * We will re-compress only idle objects equal or + * greater in size than watermark. + */ + ret = kstrtouint(val, 10, &threshold); + if (ret) + return ret; + continue; + } + } + + if (threshold >= PAGE_SIZE) + return -EINVAL; + + down_read(&zram->init_lock); + if (!init_done(zram)) { + ret = -EINVAL; + goto release_init_lock; + } + + page = alloc_page(GFP_KERNEL); + if (!page) { + ret = -ENOMEM; + goto release_init_lock; + } + + ret = len; + for (index = 0; index < nr_pages; index++) { + int err = 0; + + zram_slot_lock(zram, index); + + if (!zram_allocated(zram, index)) + goto next; + + if (mode & RECOMPRESS_IDLE && + !zram_test_flag(zram, index, ZRAM_IDLE)) + goto next; + + if (mode & RECOMPRESS_HUGE && + !zram_test_flag(zram, index, ZRAM_HUGE)) + goto next; + + if (zram_test_flag(zram, index, ZRAM_WB) || + zram_test_flag(zram, index, ZRAM_UNDER_WB) || + zram_test_flag(zram, index, ZRAM_SAME) || + zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE)) + goto next; + + err = zram_recompress(zram, index, page, threshold, + prio, ZRAM_MAX_COMPS); +next: + zram_slot_unlock(zram, index); + if (err) { + ret = err; + break; + } + + cond_resched(); + } + + __free_page(page); + +release_init_lock: + up_read(&zram->init_lock); + return ret; +} +#endif + /* * zram_bio_discard - handler on discard request * @index: physical block index in PAGE_SIZE units @@ -1999,6 +2255,7 @@ static DEVICE_ATTR_RW(writeback_limit_enable); #endif #ifdef CONFIG_ZRAM_MULTI_COMP static DEVICE_ATTR_RW(recomp_algorithm); +static DEVICE_ATTR_WO(recompress); #endif

static struct attribute *zram_disk_attrs[] = { @@ -2025,6 +2282,7 @@ static struct attribute *zram_disk_attrs[] = { &dev_attr_debug_stat.attr, #ifdef CONFIG_ZRAM_MULTI_COMP &dev_attr_recomp_algorithm.attr, + &dev_attr_recompress.attr, #endif NULL, }; diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index a3fcd6b21091..c56e216f928d 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -41,6 +41,9 @@ */ #define ZRAM_FLAG_SHIFT 24

+/* Only 2 bits are allowed for comp priority index */ +#define ZRAM_COMP_PRIORITY_MASK 0x3 + /* Flags for zram pages (table[page_no].flags) */ enum zram_pageflags { /* zram slot is locked */ @@ -50,6 +53,10 @@ enum zram_pageflags { ZRAM_UNDER_WB, /* page is under writeback */ ZRAM_HUGE, /* Incompressible page */ ZRAM_IDLE, /* not accessed page since last idle marking */ + ZRAM_INCOMPRESSIBLE, /* none of the algorithms could compress it */ + + ZRAM_COMP_PRIORITY_BIT1, /* First bit of comp priority index */ + ZRAM_COMP_PRIORITY_BIT2, /* Second bit of comp priority index */

__NR_ZRAM_PAGEFLAGS, };

From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 9fda785dbd14cfc7d874d00d2b007cb143aa48d0 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Re-phrase writeback BIO error comment.

Link: https://lkml.kernel.org/r/20221109115047.2921851-7-senozhatsky@chromium.org Reported-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/block/zram/zram_drv.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index a9b4dd68cccf..3f553ba0cc94 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -751,8 +751,12 @@ static ssize_t writeback_store(struct device *dev, zram_clear_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); /* - * Return last IO error unless every IO were - * not suceeded. + * BIO errors are not fatal, we continue and simply + * attempt to writeback the remaining objects (pages). + * At the same time we need to signal user-space that + * some writes (at least one, but also could be all of + * them) were not successful and we do so by returning + * the most recent BIO error. */ ret = err; continue;

From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 4942cf6ad07c487d24112ffbb27362f4e6b409b8 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Size class index comparison is powerful enough so we can remove object size comparisons.

Link: https://lkml.kernel.org/r/20221109115047.2921851-10-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/block/zram/zram_drv.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 81581ebe6611..07fbba6c35f2 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1697,9 +1697,7 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, comp_len_new);

/* Continue until we make progress */ - if (comp_len_new >= huge_class_size || - comp_len_new >= comp_len_old || - class_index_new >= class_index_old || + if (class_index_new >= class_index_old || (threshold && comp_len_new >= threshold)) { zcomp_stream_put(zram->comps[prio]); continue; @@ -1722,9 +1720,7 @@ static int zram_recompress(struct zram *zram, u32 index, struct page *page, * that would save memory, mark the object as incompressible so that * we will not try to compress it again. */ - if (comp_len_new >= huge_class_size || - comp_len_new >= comp_len_old || - class_index_new >= class_index_old) { + if (class_index_new >= class_index_old) { zram_set_flag(zram, index, ZRAM_INCOMPRESSIBLE); return 0; }

From: Sergey Senozhatsky senozhatsky@chromium.org

mainline inclusion from mainline-v6.2-rc1 commit 443dd798062c1549e790539e572cbda4b7a8df30 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I7TWVA CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

-------------------------------------------

Document user-space visible device attributes that are enabled by ZRAM_MULTI_COMP.

Link: https://lkml.kernel.org/r/20221109115047.2921851-12-senozhatsky@chromium.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org

Conflicts: Documentation/admin-guide/blockdev/zram.rst

Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- Documentation/admin-guide/blockdev/zram.rst | 81 +++++++++++++++++++++ 1 file changed, 81 insertions(+)

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index a70493928c3e..abb35811bd39 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -382,6 +382,87 @@ budget in next setting is user's job. If admin wants to measure writeback count in a certain period, he could know it via /sys/block/zram0/bd_stat's 3rd column.

+recompression +------------- + +With CONFIG_ZRAM_MULTI_COMP, zram can recompress pages using alternative +(secondary) compression algorithms. The basic idea is that alternative +compression algorithm can provide better compression ratio at a price of +(potentially) slower compression/decompression speeds. Alternative compression +algorithm can, for example, be more successful compressing huge pages (those +that default algorithm failed to compress). Another application is idle pages +recompression - pages that are cold and sit in the memory can be recompressed +using more effective algorithm and, hence, reduce zsmalloc memory usage. + +With CONFIG_ZRAM_MULTI_COMP, zram supports up to 4 compression algorithms: +one primary and up to 3 secondary ones. Primary zram compressor is explained +in "3) Select compression algorithm", secondary algorithms are configured +using recomp_algorithm device attribute. + +Example::: + + #show supported recompression algorithms + cat /sys/block/zramX/recomp_algorithm + #1: lzo lzo-rle lz4 lz4hc [zstd] + #2: lzo lzo-rle lz4 [lz4hc] zstd + +Alternative compression algorithms are sorted by priority. In the example +above, zstd is used as the first alternative algorithm, which has priority +of 1, while lz4hc is configured as a compression algorithm with priority 2. +Alternative compression algorithm's priority is provided during algorithms +configuration::: + + #select zstd recompression algorithm, priority 1 + echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm + + #select deflate recompression algorithm, priority 2 + echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm + +Another device attribute that CONFIG_ZRAM_MULTI_COMP enables is recompress, +which controls recompression. + +Examples::: + + #IDLE pages recompression is activated by `idle` mode + echo "type=idle" > /sys/block/zramX/recompress + + #HUGE pages recompression is activated by `huge` mode + echo "type=huge" > /sys/block/zram0/recompress + + #HUGE_IDLE pages recompression is activated by `huge_idle` mode + echo "type=huge_idle" > /sys/block/zramX/recompress + +The number of idle pages can be significant, so user-space can pass a size +threshold (in bytes) to the recompress knob: zram will recompress only pages +of equal or greater size::: + + #recompress all pages larger than 3000 bytes + echo "threshold=3000" > /sys/block/zramX/recompress + + #recompress idle pages larger than 2000 bytes + echo "type=idle threshold=2000" > /sys/block/zramX/recompress + +Recompression of idle pages requires memory tracking. + +During re-compression for every page, that matches re-compression criteria, +ZRAM iterates the list of registered alternative compression algorithms in +order of their priorities. ZRAM stops either when re-compression was +successful (re-compressed object is smaller in size than the original one) +and matches re-compression criteria (e.g. size threshold) or when there are +no secondary algorithms left to try. If none of the secondary algorithms can +successfully re-compressed the page such a page is marked as incompressible, +so ZRAM will not attempt to re-compress it in the future. + +This re-compression behaviour, when it iterates through the list of +registered compression algorithms, increases our chances of finding the +algorithm that successfully compresses a particular page. Sometimes, however, +it is convenient (and sometimes even necessary) to limit recompression to +only one particular algorithm so that it will not try any other algorithms. +This can be achieved by providing a algo=NAME parameter::: + + #use zstd algorithm only (if registered) + echo "type=huge algo=zstd" > /sys/block/zramX/recompress + memory tracking ===============

From: Sergey Senozhatsky senozhatsky@chromium.org

Add a new flag to zram block state that shows if the page is incompressible: that none of the algorithm (including secondary ones) could compress it.

Link: https://lkml.kernel.org/r/20221109115047.2921851-14-senozhatsky@chromium.org Suggested-by: Minchan Kim minchan@kernel.org Signed-off-by: Sergey Senozhatsky senozhatsky@chromium.org Acked-by: Minchan Kim minchan@kernel.org Cc: Alexey Romanov avromanov@sberdevices.ru Cc: Nhat Pham nphamcs@gmail.com Cc: Nitin Gupta ngupta@vflare.org Cc: Suleiman Souhlal suleiman@google.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- Documentation/admin-guide/blockdev/zram.rst | 11 +++++++---- drivers/block/zram/zram_drv.c | 6 ++++-- 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst index bce2e4480652..3bfb9dc67976 100644 --- a/Documentation/admin-guide/blockdev/zram.rst +++ b/Documentation/admin-guide/blockdev/zram.rst @@ -478,10 +478,11 @@ pages of the process with*pagemap. If you enable the feature, you could see block state via /sys/kernel/debug/zram/zram0/block_state". The output is as follows::

- 300 75.033841 .wh.. - 301 63.806904 s.... - 302 63.806919 ..hi. - 303 62.801919 ....r + 300 75.033841 .wh... + 301 63.806904 s..... + 302 63.806919 ..hi.. + 303 62.801919 ....r. + 304 146.781902 ..hi.n

First column zram's block index. @@ -500,6 +501,8 @@ Third column idle page r: recompressed page (secondary compression algorithm) + n: + none (including secondary) of algorithms could compress it

First line of above example says 300th block is accessed at 75.033841sec and the block's state is huge so it is written back to the backing diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 1e56e5ff562d..7e706e3eab8d 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -929,14 +929,16 @@ static ssize_t read_block_state(struct file *file, char __user *buf,

ts = ktime_to_timespec64(zram->table[index].ac_time); copied = snprintf(kbuf + written, count, - "%12zd %12lld.%06lu %c%c%c%c%c\n", + "%12zd %12lld.%06lu %c%c%c%c%c%c\n", index, (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC, zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.', zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.', zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.', - zram_get_priority(zram, index) ? 'r' : '.'); + zram_get_priority(zram, index) ? 'r' : '.', + zram_test_flag(zram, index, + ZRAM_INCOMPRESSIBLE) ? 'n' : '.');

if (count <= copied) { zram_slot_unlock(zram, index);