On Mon, Apr 06, 2020 at 08:54:07AM -0400, Yafang Shao wrote: > When I run my memcg testcase which creates lots of memcgs, I found > there're unexpected out of memory logs while there're still enough > available free memory. The error log is, > mkdir: cannot create directory 'foo.65533': Cannot allocate memory > > The reason is when we try to create more than MEM_CGROUP_ID_MAX memcgs, an > -ENOMEM errno will be set by mem_cgroup_css_alloc(), but the right errno > should be -ENOSPC, as explained above the function idr_alloc(). I think idr_alloc() is wrong. I think the right errno to return here is EBUSY "Device or resource busy". > -static struct mem_cgroup *mem_cgroup_alloc(void) > +static struct mem_cgroup *mem_cgroup_alloc(long *error) The normal way to do this is to return an ERR_PTR(). See include/linux/err.h.
