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mm/zswap: add the flag can_sleep_mapped 

Patch series "Fix the compatibility of zsmalloc and zswap".

Patch #1 adds a flag to zpool, then zswap used to determine if zpool
drivers such as zbud/z3fold/zsmalloc will enter an atomic context after
mapping.

The difference between zbud/z3fold and zsmalloc is that zsmalloc requires
an atomic context that since its map function holds a preempt-disabled,
but zbud/z3fold don't require an atomic context.  So patch #2 sets flag
sleep_mapped to true indicating that zbud/z3fold can sleep after mapping.
zsmalloc didn't support sleep after mapping, so don't set that flag to
true.

This patch (of 2):

Add a flag to zpool, named is "can_sleep_mapped", and have it set true for
zbud/z3fold, not set this flag for zsmalloc, so its default value is
false.  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.

[natechancellor@gmail.com: add return value in zswap_frontswap_load]
  Link: https://lkml.kernel.org/r/20210121214804.926843-1-natechancellor@gmail.com
[tiantao6@hisilicon.com: fix potential memory leak]
  Link: https://lkml.kernel.org/r/1611538365-51811-1-git-send-email-tiantao6@hisilicon.com
[colin.king@canonical.com: fix potential uninitialized pointer read on tmp]
  Link: https://lkml.kernel.org/r/20210128141728.639030-1-colin.king@canonical.com
[tiantao6@hisilicon.com: fix variable 'entry' is uninitialized when used]
  Link: https://lkml.kernel.org/r/1611223030-58346-1-git-send-email-tiantao6@hisilicon.comLink: https://lkml.kernel.org/r/1611035683-12732-1-git-send-email-tiantao6@hisilicon.com

Link: https://lkml.kernel.org/r/1611035683-12732-2-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: Mike Galbraith <efault@gmx.de>
Cc: Barry Song <song.bao.hua@hisilicon.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
master
Tian Tao 2021-02-25 17:18:17 -08:00 committed by Linus Torvalds
parent c0c641d77b
commit fc6697a89f
3 changed files with 62 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/zpool.h
View File

@ -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

13
mm/zpool.c
View File

@ -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@ieee.org>");
MODULE_DESCRIPTION("Common API for compressed memory storage");

51
mm/zswap.c
View File

@ -935,13 +935,19 @@ 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 = NULL;
unsigned int dlen;
int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
if (!zpool_can_sleep_mapped(pool)) {
tmp = kmalloc(PAGE_SIZE, GFP_ATOMIC);
if (!tmp)
return -ENOMEM;
}
/* extract swpentry from data */
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
swpentry = zhdr->swpentry; /* here */
@ -955,6 +961,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
/* entry was invalidated */
spin_unlock(&tree->lock);
zpool_unmap_handle(pool, handle);
kfree(tmp);
return 0;
}
spin_unlock(&tree->lock);
@ -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 @@ fail:
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;
@ -1253,15 +1272,33 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
dst = kmap_atomic(page);
zswap_fill_page(dst, entry->value);
kunmap_atomic(dst);
ret = 0;
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 +1308,11 @@ 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 +1320,7 @@ freeentry:
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
return 0;
return ret;
}
/* frees an entry in zswap */