2020-05-02 02:05:53

by Barry Song

[permalink] [raw]
Subject: [PATCH 0/1] mm/zswap: move to use crypto_acomp APIs

Hi Seth, Dan, Vitaly, Herbert,

Using crypto_comp APIs, zswap is not able to use the hardware accelators which
are only ported to cryto_acomp nowadays. So Mahipal Challa tried to solve this
problem by the below patch a long time ago:
mm: zswap - Add crypto acomp/scomp framework support [1]

At that time, the test was based on acomp with scomp backend. It was not a real
async platform. On a platform with real acomp support like hisilicon-zip, the
patch will lead to serious "sleep on atomic" issues.

To leverage the power of hardware accelerator, right now, I am sending a new patch
which will remove the atomic context and permit crypto to sleep in zswap.

Literally, using an async compressor, people can dynamically allocate acomp_req and
queue those requests to acrytp drivers, and finally use the callback to notify
the completion of compression/decompression. but this will require dynamic memory
allocation and various synchronizations in zswap, and it is too complex.

Alternatively, this patch pre-allocates the acomp_req with the same number of CPUs.
For each acomp_req, one mutex and one wait are bound with it. The mutex is used
for the race protection of the acomp_req and other percpu resources. Even though
the preempt-disabled atomic context is replaced by sleepable context, threads
might migrate, but the mutex can still protect the race between CPUs for same
resources.

Tested on hisilicon zip driver on a SMP enviorment and on lz4 scomp-based acomp
as well. To use scomp-based acomp, another patch I sent before is needed:
crypto: acomp - search acomp with scomp backend in crypto_has_acomp [2]

[1] https://www.spinics.net/lists/linux-mm/msg122455.html
[2] https://marc.info/?l=linux-crypto-vger&m=158822346227760&w=2

Barry Song (1):
mm/zswap: move to use crypto_acomp API for hardware acceleration

mm/zswap.c | 150 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 108 insertions(+), 42 deletions(-)

--
2.23.0



2020-05-02 02:05:53

by Barry Song

[permalink] [raw]
Subject: [PATCH 1/1] mm/zswap: move to use crypto_acomp API for hardware acceleration

right now, new drivers are adapted to crypto_acomp APIs rather than crypto_comp
APIs. Tradiontal compressors like lz4,lzo etc have been wrapped into acomp via
scomp backend as well.
To use the new hardware acceleration for compression, zswap should move to use
acomp APIs. Platforms without async accelerators can still work through scomp.

Signed-off-by: Barry Song <[email protected]>
---
mm/zswap.c | 150 ++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 108 insertions(+), 42 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index fbb782924ccc..44a982632deb 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -24,8 +24,10 @@
#include <linux/rbtree.h>
#include <linux/swap.h>
#include <linux/crypto.h>
+#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/zpool.h>
+#include <crypto/acompress.h>

#include <linux/mm_types.h>
#include <linux/page-flags.h>
@@ -127,9 +129,16 @@ module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
* data structures
**********************************/

+struct crypto_acomp_ctx {
+ struct crypto_acomp *acomp;
+ struct acomp_req *req;
+ struct crypto_wait wait;
+ struct mutex mutex;
+};
+
struct zswap_pool {
struct zpool *zpool;
- struct crypto_comp * __percpu *tfm;
+ struct crypto_acomp_ctx * __percpu *acomp_ctx;
struct kref kref;
struct list_head list;
struct work_struct release_work;
@@ -415,30 +424,59 @@ static int zswap_dstmem_dead(unsigned int cpu)
static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
- struct crypto_comp *tfm;
+ struct crypto_acomp *acomp;
+ struct acomp_req *req;
+ struct crypto_acomp_ctx *acomp_ctx;

- if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
+ if (WARN_ON(*per_cpu_ptr(pool->acomp_ctx, cpu)))
return 0;

- tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
- if (IS_ERR_OR_NULL(tfm)) {
- pr_err("could not alloc crypto comp %s : %ld\n",
- pool->tfm_name, PTR_ERR(tfm));
+ acomp_ctx = kzalloc(sizeof(*acomp_ctx), GFP_KERNEL);
+ if (IS_ERR_OR_NULL(acomp_ctx)) {
+ pr_err("Could not initialize acomp_ctx\n");
+ return -ENOMEM;
+ }
+ acomp = crypto_alloc_acomp(pool->tfm_name, 0, 0);
+ if (IS_ERR_OR_NULL(acomp)) {
+ pr_err("could not alloc crypto acomp %s : %ld\n",
+ pool->tfm_name, PTR_ERR(acomp));
+ return -ENOMEM;
+ }
+ acomp_ctx->acomp = acomp;
+
+ req = acomp_request_alloc(acomp_ctx->acomp);
+ if (IS_ERR_OR_NULL(req)) {
+ pr_err("could not alloc crypto acomp %s : %ld\n",
+ pool->tfm_name, PTR_ERR(acomp));
return -ENOMEM;
}
- *per_cpu_ptr(pool->tfm, cpu) = tfm;
+ acomp_ctx->req = req;
+
+ mutex_init(&acomp_ctx->mutex);
+ crypto_init_wait(&acomp_ctx->wait);
+ acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+ crypto_req_done, &acomp_ctx->wait);
+
+ *per_cpu_ptr(pool->acomp_ctx, cpu) = acomp_ctx;
+
return 0;
}

static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
- struct crypto_comp *tfm;
+ struct crypto_acomp_ctx *acomp_ctx;
+
+ acomp_ctx = *per_cpu_ptr(pool->acomp_ctx, cpu);
+ if (!IS_ERR_OR_NULL(acomp_ctx)) {
+ if (!IS_ERR_OR_NULL(acomp_ctx->req))
+ acomp_request_free(acomp_ctx->req);
+ if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
+ crypto_free_acomp(acomp_ctx->acomp);
+ kfree(acomp_ctx);
+ }
+ *per_cpu_ptr(pool->acomp_ctx, cpu) = NULL;

- tfm = *per_cpu_ptr(pool->tfm, cpu);
- if (!IS_ERR_OR_NULL(tfm))
- crypto_free_comp(tfm);
- *per_cpu_ptr(pool->tfm, cpu) = NULL;
return 0;
}

@@ -561,8 +599,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));

strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
- pool->tfm = alloc_percpu(struct crypto_comp *);
- if (!pool->tfm) {
+
+ pool->acomp_ctx = alloc_percpu(struct crypto_acomp_ctx *);
+ if (!pool->acomp_ctx) {
pr_err("percpu alloc failed\n");
goto error;
}
@@ -585,7 +624,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
return pool;

error:
- free_percpu(pool->tfm);
+ free_percpu(pool->acomp_ctx);
if (pool->zpool)
zpool_destroy_pool(pool->zpool);
kfree(pool);
@@ -596,14 +635,14 @@ static __init struct zswap_pool *__zswap_pool_create_fallback(void)
{
bool has_comp, has_zpool;

- has_comp = crypto_has_comp(zswap_compressor, 0, 0);
+ has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
if (!has_comp && strcmp(zswap_compressor,
CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
pr_err("compressor %s not available, using default %s\n",
zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
param_free_charp(&zswap_compressor);
zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
- has_comp = crypto_has_comp(zswap_compressor, 0, 0);
+ has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
}
if (!has_comp) {
pr_err("default compressor %s not available\n",
@@ -639,7 +678,7 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
zswap_pool_debug("destroying", pool);

cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
- free_percpu(pool->tfm);
+ free_percpu(pool->acomp_ctx);
zpool_destroy_pool(pool->zpool);
kfree(pool);
}
@@ -723,7 +762,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
}
type = s;
} else if (!compressor) {
- if (!crypto_has_comp(s, 0, 0)) {
+ if (!crypto_has_acomp(s, 0, 0)) {
pr_err("compressor %s not available\n", s);
return -ENOENT;
}
@@ -774,7 +813,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
* failed, maybe both compressor and zpool params were bad.
* Allow changing this param, so pool creation will succeed
* when the other param is changed. We already verified this
- * param is ok in the zpool_has_pool() or crypto_has_comp()
+ * param is ok in the zpool_has_pool() or crypto_has_acomp()
* checks above.
*/
ret = param_set_charp(s, kp);
@@ -876,7 +915,9 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
pgoff_t offset;
struct zswap_entry *entry;
struct page *page;
- struct crypto_comp *tfm;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
+
u8 *src, *dst;
unsigned int dlen;
int ret;
@@ -916,14 +957,21 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)

case ZSWAP_SWAPCACHE_NEW: /* page is locked */
/* decompress */
+ acomp_ctx = *this_cpu_ptr(entry->pool->acomp_ctx);
+
dlen = PAGE_SIZE;
src = (u8 *)zhdr + sizeof(struct zswap_header);
- dst = kmap_atomic(page);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- ret = crypto_comp_decompress(tfm, src, entry->length,
- dst, &dlen);
- put_cpu_ptr(entry->pool->tfm);
- kunmap_atomic(dst);
+ dst = kmap(page);
+
+ mutex_lock(&acomp_ctx->mutex);
+ sg_init_one(&input, src, entry->length);
+ sg_init_one(&output, dst, dlen);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
+ ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
+ dlen = acomp_ctx->req->dlen;
+ mutex_unlock(&acomp_ctx->mutex);
+
+ kunmap(page);
BUG_ON(ret);
BUG_ON(dlen != PAGE_SIZE);

@@ -1004,7 +1052,8 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry, *dupentry;
- struct crypto_comp *tfm;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
int ret;
unsigned int hlen, dlen = PAGE_SIZE;
unsigned long handle, value;
@@ -1075,11 +1124,20 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,

/* compress */
dst = get_cpu_var(zswap_dstmem);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- src = kmap_atomic(page);
- ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
- kunmap_atomic(src);
- put_cpu_ptr(entry->pool->tfm);
+ acomp_ctx = *this_cpu_ptr(entry->pool->acomp_ctx);
+ put_cpu_var(zswap_dstmem);
+
+ mutex_lock(&acomp_ctx->mutex);
+
+ src = kmap(page);
+ sg_init_one(&input, src, PAGE_SIZE);
+ /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
+ sg_init_one(&output, dst, PAGE_SIZE * 2);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
+ ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
+ dlen = acomp_ctx->req->dlen;
+ kunmap(page);
+
if (ret) {
ret = -EINVAL;
goto put_dstmem;
@@ -1103,7 +1161,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
memcpy(buf, &zhdr, hlen);
memcpy(buf + hlen, dst, dlen);
zpool_unmap_handle(entry->pool->zpool, handle);
- put_cpu_var(zswap_dstmem);
+ mutex_unlock(&acomp_ctx->mutex);

/* populate entry */
entry->offset = offset;
@@ -1131,7 +1189,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
return 0;

put_dstmem:
- put_cpu_var(zswap_dstmem);
+ mutex_unlock(&acomp_ctx->mutex);
zswap_pool_put(entry->pool);
freepage:
zswap_entry_cache_free(entry);
@@ -1148,7 +1206,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
- struct crypto_comp *tfm;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
u8 *src, *dst;
unsigned int dlen;
int ret;
@@ -1175,11 +1234,18 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
if (zpool_evictable(entry->pool->zpool))
src += sizeof(struct zswap_header);
- dst = kmap_atomic(page);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
- put_cpu_ptr(entry->pool->tfm);
- kunmap_atomic(dst);
+ dst = kmap(page);
+
+ acomp_ctx = *this_cpu_ptr(entry->pool->acomp_ctx);
+ mutex_lock(&acomp_ctx->mutex);
+ sg_init_one(&input, src, entry->length);
+ sg_init_one(&output, dst, dlen);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
+ ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
+ dlen = acomp_ctx->req->dlen;
+ mutex_unlock(&acomp_ctx->mutex);
+
+ kunmap(page);
zpool_unmap_handle(entry->pool->zpool, entry->handle);
BUG_ON(ret);

--
2.23.0