f2fs: avoid double lock for cp_rwsem

The __f2fs_add_link is covered by cp_rwsem all the time. This calls init_inode_metadata, which conducts some acl operations including memory allocation with GFP_KERNEL previously. But, under memory pressure, f2fs_write_data_page can be called, which also grabs cp_rwsem too. In this case, this incurs a deadlock pointed by Chao. Thread kerneltoast#1 Thread kerneltoast#2 down_read down_write down_read -> here down_read should wait forever. Reviewed-by: Chao Yu <[email protected]> Signed-off-by: Jaegeuk Kim <[email protected]>
tmimsk · Jan 12, 2015 · 436d931 · 436d931
1 parent fc5e466
commit 436d931
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
@@ -62,7 +62,7 @@ static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size)
 	if (count == 0)
 		return NULL;
 
-	acl = posix_acl_alloc(count, GFP_KERNEL);
+	acl = posix_acl_alloc(count, GFP_NOFS);
 	if (!acl)
 		return ERR_PTR(-ENOMEM);
 
@@ -116,7 +116,7 @@ static void *f2fs_acl_to_disk(const struct posix_acl *acl, size_t *size)
 	int i;
 
 	f2fs_acl = kmalloc(sizeof(struct f2fs_acl_header) + acl->a_count *
-			sizeof(struct f2fs_acl_entry), GFP_KERNEL);
+			sizeof(struct f2fs_acl_entry), GFP_NOFS);
 	if (!f2fs_acl)
 		return ERR_PTR(-ENOMEM);