linux-kernel - [PATCH v6 14/16] mm: memcontrol: fix cannot alloc the maximum memcg ID

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Message-Id: <20220228122126.37293-15-songmuchun@bytedance.com>
Date:   Mon, 28 Feb 2022 20:21:24 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     willy@...radead.org, akpm@...ux-foundation.org, hannes@...xchg.org,
        mhocko@...nel.org, vdavydov.dev@...il.com, shakeelb@...gle.com,
        roman.gushchin@...ux.dev, shy828301@...il.com, alexs@...nel.org,
        richard.weiyang@...il.com, david@...morbit.com,
        trond.myklebust@...merspace.com, anna.schumaker@...app.com,
        jaegeuk@...nel.org, chao@...nel.org, kari.argillander@...il.com,
        vbabka@...e.cz
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-nfs@...r.kernel.org,
        zhengqi.arch@...edance.com, duanxiongchun@...edance.com,
        fam.zheng@...edance.com, smuchun@...il.com,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH v6 14/16] mm: memcontrol: fix cannot alloc the maximum memcg ID

The idr_alloc() does not include @max ID. So in the current implementation,
the maximum memcg ID is 65534 instead of 65535. It seems a bug. So fix this.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/memcontrol.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 809dfa4b2abc..cbe6f9bb37bb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5029,8 +5029,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 		return ERR_PTR(error);
 
 	memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
-				 1, MEM_CGROUP_ID_MAX,
-				 GFP_KERNEL);
+				 1, MEM_CGROUP_ID_MAX + 1, GFP_KERNEL);
 	if (memcg->id.id < 0) {
 		error = memcg->id.id;
 		goto fail;
-- 
2.11.0