mm: fix nr_rotate_swap leak in swapon() error case
If swapon() fails after incrementing nr_rotate_swap, we don't decrement
it and thus effectively leak it. Make sure we decrement it if we
incremented it.
Link: http://lkml.kernel.org/r/b6fe6b879f17fa68eee6cbd876f459f6e5e33495.1526491581.git.osandov@fb.com
Fixes: 81a0298bdfab ("mm, swap: don't use VMA based swap readahead if HDD is used as swap")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index cc2cf04..78a015f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3112,6 +3112,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
unsigned long *frontswap_map = NULL;
struct page *page = NULL;
struct inode *inode = NULL;
+ bool inced_nr_rotate_swap = false;
if (swap_flags & ~SWAP_FLAGS_VALID)
return -EINVAL;
@@ -3215,8 +3216,10 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
cluster = per_cpu_ptr(p->percpu_cluster, cpu);
cluster_set_null(&cluster->index);
}
- } else
+ } else {
atomic_inc(&nr_rotate_swap);
+ inced_nr_rotate_swap = true;
+ }
error = swap_cgroup_swapon(p->type, maxpages);
if (error)
@@ -3307,6 +3310,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
vfree(swap_map);
kvfree(cluster_info);
kvfree(frontswap_map);
+ if (inced_nr_rotate_swap)
+ atomic_dec(&nr_rotate_swap);
if (swap_file) {
if (inode && S_ISREG(inode->i_mode)) {
inode_unlock(inode);