[PATCH v2] mm: shrinker: avoid memleak in alloc_shrinker_info

[Chen Ridong <chenridong@xxxxxxxxxxxxxxx>]

From: Chen Ridong <chenridong@xxxxxxxxxx>

A memleak was found as bellow:

unreferenced object 0xffff8881010d2a80 (size 32):
  comm "mkdir", pid 1559, jiffies 4294932666
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  @...............
  backtrace (crc 2e7ef6fa):
    [<ffffffff81372754>] __kmalloc_node_noprof+0x394/0x470
    [<ffffffff813024ab>] alloc_shrinker_info+0x7b/0x1a0
    [<ffffffff813b526a>] mem_cgroup_css_online+0x11a/0x3b0
    [<ffffffff81198dd9>] online_css+0x29/0xa0
    [<ffffffff811a243d>] cgroup_apply_control_enable+0x20d/0x360
    [<ffffffff811a5728>] cgroup_mkdir+0x168/0x5f0
    [<ffffffff8148543e>] kernfs_iop_mkdir+0x5e/0x90
    [<ffffffff813dbb24>] vfs_mkdir+0x144/0x220
    [<ffffffff813e1c97>] do_mkdirat+0x87/0x130
    [<ffffffff813e1de9>] __x64_sys_mkdir+0x49/0x70
    [<ffffffff81f8c928>] do_syscall_64+0x68/0x140
    [<ffffffff8200012f>] entry_SYSCALL_64_after_hwframe+0x76/0x7e

In the alloc_shrinker_info function, when shrinker_unit_alloc return
err, the info won't be freed. Just fix it.

Fixes: 307bececcd12 ("mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}")
Signed-off-by: Chen Ridong <chenridong@xxxxxxxxxx>
---
 mm/shrinker.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/shrinker.c b/mm/shrinker.c
index dc5d2a6fcfc4..92270413190d 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -97,6 +97,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg)
 
 err:
 	mutex_unlock(&shrinker_mutex);
+	kvfree(info);
 	free_shrinker_info(memcg);
 	return -ENOMEM;
 }
-- 
2.34.1