On 2012/12/12 19:23, Michal Hocko wrote: > On Wed 12-12-12 18:44:13, Xishi Qiu wrote: >> On 2012/12/12 18:19, Michal Hocko wrote: >> >>> On Wed 12-12-12 16:25:59, Jianguo Wu wrote: >>>> Build kernel with CONFIG_HUGETLBFS=y,CONFIG_HUGETLB_PAGE=y >>>> and CONFIG_CGROUP_HUGETLB=y, then specify hugepagesz=xx boot option, >>>> system will boot fail. >>>> >>>> This failure is caused by following code path: >>>> setup_hugepagesz >>>> hugetlb_add_hstate >>>> hugetlb_cgroup_file_init >>>> cgroup_add_cftypes >>>> kzalloc <--slab is *not available* yet >>>> >>>> For this path, slab is not available yet, so memory allocated will be >>>> failed, and cause WARN_ON() in hugetlb_cgroup_file_init(). >>>> >>>> So I move hugetlb_cgroup_file_init() into hugetlb_init(). >>> >>> I do not think this is a good idea. hugetlb_init is in __init section as >>> well so what guarantees that the slab is initialized by then? Isn't this >>> just a good ordering that makes this working? >> >> Hi Michal, >> >> __initcall functions will be called in >> start_kernel() >> rest_init() // -> slab is already >> kernel_init() >> kernel_init_freeable() >> do_basic_setup() >> do_initcalls() >> >> and setup_hugepagesz() will be called in >> start_kernel() >> parse_early_param() // -> before mm_init() -> kmem_cache_init() >> >> Is this right? > > Yes this is right. I just noticed that kmem_cache_init_late is an __init > function as well and didn't realize it is called directly. Sorry about > the confusion. > Anyway I still think it would be a better idea to move the call into the > hugetlb_cgroup_create callback where it is more logical IMO but now that Hi Michal, Thanks for your review and comments:). hugetlb_cgroup_create is a callback of hugetlb_subsys, and hugetlb_cgroup_file_init add h->cgroup_files to hugetlb_subsys, so we cann't move hugetlb_cgroup_file_init into hugetlb_cgroup_create, right? Thanks, Jianguo wu > I'm looking at other controllers (blk and kmem.tcp) they all do this from > init calls as well. So it doesn't make sense to have hugetlb behave > differently. > > So > Acked-by: Michal Hocko <mhocko@xxxxxxx> > > Thanks! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>