From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: 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. Link: https://lkml.kernel.org/r/20220228122126.37293-15-songmuchun@xxxxxxxxxxxxx Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Cc: Alex Shi <alexs@xxxxxxxxxx> Cc: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Cc: Chao Yu <chao@xxxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Fam Zheng <fam.zheng@xxxxxxxxxxxxx> Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Kari Argillander <kari.argillander@xxxxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Theodore Ts'o <tytso@xxxxxxx> Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxx> Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx> Cc: Yang Shi <shy828301@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/mm/memcontrol.c~mm-memcontrol-fix-cannot-alloc-the-maximum-memcg-id +++ a/mm/memcontrol.c @@ -5088,8 +5088,7 @@ static struct mem_cgroup *mem_cgroup_all 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; _
