[PATCH] mm: Fix potential memory leak in sys_swapon

[Miaohe Lin]

If we failed to drain inode, we would forget to free the swap address space
allocated by init_swap_address_space() above.

Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
Signed-off-by: Miaohe Lin <linmia...@huawei.com>
---
 mm/swapfile.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 2b0c5fc1b0e6..4522b458a814 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3342,7 +3342,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, 
int, swap_flags)
        error = inode_drain_writes(inode);
        if (error) {
                inode->i_flags &= ~S_SWAPFILE;
-               goto bad_swap_unlock_inode;
+               goto free_swap_address_space;
        }
 
        mutex_lock(&swapon_mutex);
@@ -3367,6 +3367,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, 
int, swap_flags)
 
        error = 0;
        goto out;
+free_swap_address_space:
+       exit_swap_address_space(p->type);
 bad_swap_unlock_inode:
        inode_unlock(inode);
 bad_swap:
-- 
2.19.1