mm: fix nr_rotate_swap leak in swapon() error case (7cbf3192) · Commits · 戴 / test

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: ("mm, swap: don't use VMA based swap readahead if HDD is used as swap") Signed-off-by:

mm/swapfile.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -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 @@ bad_swap:
		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);