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Message-ID: <b9f5c74a-acc5-42b4-bb7e-0b4f487486c6@bytedance.com>
Date: Fri, 25 Oct 2024 15:12:03 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Chen Ridong <chenridong@...weicloud.com>
Cc: akpm@...ux-foundation.org, david@...morbit.com, roman.gushchin@...ux.dev,
muchun.song@...ux.dev, anshuman.khandual@....com, vbabka@...e.cz,
kirill@...temov.name, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
chenridong@...wei.com, wangweiyang2@...wei.com
Subject: Re: [PATCH v3] mm: shrinker: avoid memleak in alloc_shrinker_info
On 2024/10/25 14:09, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
>
> 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}")
Again, please:
Cc: stable@...r.kernel.org
I think Andrew can help add that. ;)
Thanks!
> Signed-off-by: Chen Ridong <chenridong@...wei.com>
> Acked-by: Qi Zheng <zhengqi.arch@...edance.com>
> Acked-by: Roman Gushchin <roman.gushchin@...ux.dev>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> mm/shrinker.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/mm/shrinker.c b/mm/shrinker.c
> index dc5d2a6fcfc4..4a93fd433689 100644
> --- a/mm/shrinker.c
> +++ b/mm/shrinker.c
> @@ -76,19 +76,21 @@ void free_shrinker_info(struct mem_cgroup *memcg)
>
> int alloc_shrinker_info(struct mem_cgroup *memcg)
> {
> - struct shrinker_info *info;
> int nid, ret = 0;
> int array_size = 0;
>
> mutex_lock(&shrinker_mutex);
> array_size = shrinker_unit_size(shrinker_nr_max);
> for_each_node(nid) {
> - info = kvzalloc_node(sizeof(*info) + array_size, GFP_KERNEL, nid);
> + struct shrinker_info *info = kvzalloc_node(sizeof(*info) + array_size,
> + GFP_KERNEL, nid);
> if (!info)
> goto err;
> info->map_nr_max = shrinker_nr_max;
> - if (shrinker_unit_alloc(info, NULL, nid))
> + if (shrinker_unit_alloc(info, NULL, nid)) {
> + kvfree(info);
> goto err;
> + }
> rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);
> }
> mutex_unlock(&shrinker_mutex);
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