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>>> long error; >>> >>> - memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL); >>> + memcg = likely(memcg_cachep) ? >>> + kmem_cache_zalloc(memcg_cachep, GFP_KERNEL) : >>> + kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), >>> + GFP_KERNEL); >> Why are we testing for memcg_cachep=NULL? >> >>> @@ -5055,6 +5061,10 @@ static int __init mem_cgroup_init(void) >>> INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work, >>> drain_local_stock); >>> >>> + memcg_size = struct_size_t(struct mem_cgroup, nodeinfo, nr_node_ids); >>> + memcg_cachep = kmem_cache_create("mem_cgroup", memcg_size, 0, >>> + SLAB_PANIC | SLAB_HWCACHE_ALIGN, NULL); >> If it's because this allocation might have failed then let's not >> bother. If an __init-time allocation failed, this kernel is unusable >> anyway. >> >> +1 to Andrew's point. SLAB_PANIC is used here, so, memcg_cachep can't be >> NULL later. I see cgroup_init(in start_kernel) ahead of initcall( which in rest_init->kernel_init->...->initcall). So, root_mem_cgroup create use cachep will trigger NULL pointer access. Thanks, Huan