add a flag to zpool, named is "can_sleep_mapped", and have it set true
for zbud/z3fold, set false for zsmalloc. Then zswap could go the current
path if the flag is true; and if it's false, copy data from src to a
temporary buffer, then unmap the handle, take the mutex, process the
buffer instead of src to avoid sleeping function called from atomic
context.
Signed-off-by: Tian Tao <tiantao6@xxxxxxxxxxxxx>
---
include/linux/zpool.h | 3 +++
mm/zpool.c | 13 +++++++++++++
mm/zswap.c | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
3 files changed, 61 insertions(+), 5 deletions(-)
diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 51bf430..e899701 100644
--- a/include/linux/zpool.h
+++ b/include/linux/zpool.h
@@ -73,6 +73,7 @@ u64 zpool_get_total_size(struct zpool *pool);
* @malloc: allocate mem from a pool.
* @free: free mem from a pool.
* @shrink: shrink the pool.
+ * @sleep_mapped: whether zpool driver can sleep during map.
* @map: map a handle.
* @unmap: unmap a handle.
* @total_size: get total size of a pool.
@@ -100,6 +101,7 @@ struct zpool_driver {
int (*shrink)(void *pool, unsigned int pages,
unsigned int *reclaimed);
+ bool sleep_mapped;
void *(*map)(void *pool, unsigned long handle,
enum zpool_mapmode mm);
void (*unmap)(void *pool, unsigned long handle);
@@ -112,5 +114,6 @@ void zpool_register_driver(struct zpool_driver *driver);
int zpool_unregister_driver(struct zpool_driver *driver);
bool zpool_evictable(struct zpool *pool);
+bool zpool_can_sleep_mapped(struct zpool *pool);
#endif
diff --git a/mm/zpool.c b/mm/zpool.c
index 3744a2d..5ed7120 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -23,6 +23,7 @@ struct zpool {
void *pool;
const struct zpool_ops *ops;
bool evictable;
+ bool can_sleep_mapped;
struct list_head list;
};
@@ -183,6 +184,7 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
zpool->pool = driver->create(name, gfp, ops, zpool);
zpool->ops = ops;
zpool->evictable = driver->shrink && ops && ops->evict;
+ zpool->can_sleep_mapped = driver->sleep_mapped;
if (!zpool->pool) {
pr_err("couldn't create %s pool\n", type);
@@ -393,6 +395,17 @@ bool zpool_evictable(struct zpool *zpool)
return zpool->evictable;
}
+/**
+ * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
+ * @zpool: The zpool to test
+ *
+ * Returns: true if zpool can sleep; false otherwise.
+ */
+bool zpool_can_sleep_mapped(struct zpool *zpool)
+{
+ return zpool->can_sleep_mapped;
+}
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Streetman <ddstreet@xxxxxxxx>");
MODULE_DESCRIPTION("Common API for compressed memory storage");
diff --git a/mm/zswap.c b/mm/zswap.c
index 182f6ad..67d4555 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -935,13 +935,20 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
struct scatterlist input, output;
struct crypto_acomp_ctx *acomp_ctx;
- u8 *src;
+ u8 *src, *tmp;
unsigned int dlen;
int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
+ if (!zpool_can_sleep_mapped(pool)) {
+
+ tmp = kmalloc(entry->length, GFP_ATOMIC);
+ if (!tmp)
+ return -ENOMEM;
+ }
+
/* extract swpentry from data */
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
swpentry = zhdr->swpentry; /* here */
@@ -979,6 +986,14 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
dlen = PAGE_SIZE;
src = (u8 *)zhdr + sizeof(struct zswap_header);
+ if (!zpool_can_sleep_mapped(pool)) {
+
+ memcpy(tmp, src, entry->length);
+ src = tmp;
+
+ zpool_unmap_handle(pool, handle);
+ }
+
mutex_lock(acomp_ctx->mutex);
sg_init_one(&input, src, entry->length);
sg_init_table(&output, 1);
@@ -1033,7 +1048,11 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
spin_unlock(&tree->lock);
end:
- zpool_unmap_handle(pool, handle);
+ if (zpool_can_sleep_mapped(pool))
+ zpool_unmap_handle(pool, handle);
+ else
+ kfree(tmp);
+
return ret;
}
@@ -1235,7 +1254,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
struct zswap_entry *entry;
struct scatterlist input, output;
struct crypto_acomp_ctx *acomp_ctx;
- u8 *src, *dst;
+ u8 *src, *dst, *tmp;
unsigned int dlen;
int ret;
@@ -1256,12 +1275,29 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
goto freeentry;
}
+ if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
+
+ tmp = kmalloc(entry->length, GFP_ATOMIC);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto freeentry;
+ }
+ }
+
/* decompress */
dlen = PAGE_SIZE;
src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
if (zpool_evictable(entry->pool->zpool))
src += sizeof(struct zswap_header);
+ if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
+
+ memcpy(tmp, src, entry->length);
+ src = tmp;
+
+ zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ }
+
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
mutex_lock(acomp_ctx->mutex);
sg_init_one(&input, src, entry->length);
@@ -1271,7 +1307,11 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
mutex_unlock(acomp_ctx->mutex);
- zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ if (zpool_can_sleep_mapped(entry->pool->zpool))
+ zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ else
+ kfree(tmp);
+
BUG_ON(ret);
freeentry:
@@ -1279,7 +1319,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
- return 0;
+ return ret;
}
/* frees an entry in zswap */
--
2.7.4
