From: Tian Tao
mainline inclusion
from mainline-5.12-rc1
commit fc6697a89f56d9773b2fbff718d4cf2a6d63379d
category: bugfix
issue: #I3ZXZF
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
-------------------------------------------------
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@hisilic...
[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@hisilic...: https://lkml.kernel.org/r/1611035683-12732-1-git-send-email-tiantao6@hisilic...
Link: https://lkml.kernel.org/r/1611035683-12732-2-git-send-email-tiantao6@hisilic...
Signed-off-by: Tian Tao
Signed-off-by: Nathan Chancellor
Signed-off-by: Colin Ian King
Reviewed-by: Vitaly Wool
Acked-by: Sebastian Andrzej Siewior
Reported-by: Mike Galbraith
Cc: Barry Song
Cc: Dan Streetman
Cc: Seth Jennings
Cc: Dan Carpenter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Chen Huang
Reviewed-by: Kefeng Wang
Signed-off-by: Chen Jun
Signed-off-by: Yu Changchun
---
include/linux/zpool.h | 3 +++
mm/zpool.c | 13 +++++++++++
mm/zswap.c | 50 +++++++++++++++++++++++++++++++++++++------
3 files changed, 60 insertions(+), 6 deletions(-)
diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 51bf43076165..e8997010612a 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 3744a2d1a624..5ed71207ced7 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 ");
MODULE_DESCRIPTION("Common API for compressed memory storage");
diff --git a/mm/zswap.c b/mm/zswap.c
index fbb782924ccc..4c6ce385c4e7 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -877,13 +877,19 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
struct zswap_entry *entry;
struct page *page;
struct crypto_comp *tfm;
- u8 *src, *dst;
+ u8 *src, *dst, *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 */
@@ -897,11 +903,19 @@ 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);
BUG_ON(offset != entry->offset);
+ 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);
+ }
+
/* try to allocate swap cache page */
switch (zswap_get_swap_cache_page(swpentry, &page)) {
case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
@@ -917,7 +931,6 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
case ZSWAP_SWAPCACHE_NEW: /* page is locked */
/* decompress */
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,
@@ -969,7 +982,11 @@ 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;
}
@@ -1149,7 +1166,7 @@ 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;
- u8 *src, *dst;
+ u8 *src, *dst, *tmp;
unsigned int dlen;
int ret;
@@ -1167,20 +1184,41 @@ 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);
+ }
+
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);
- 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:
@@ -1188,7 +1226,7 @@ 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 */
--
2.22.0
