From: Balbir Singh and Li Zefan mm owner fix. This patch allows mm->owner to be NULL when mm_owner callback is called. Without this patch, (for example) you can see panic while you do migrate a set of task, which calls fork/exit. Signed-off-by: Balbir Singh Signed-off-by: Li Zefan Tested-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton --- mm/memrlimitcgroup.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff -puN mm/memrlimitcgroup.c~memrlimit-add-memrlimit-controller-accounting-and-control-mm_owner-fix mm/memrlimitcgroup.c --- a/mm/memrlimitcgroup.c~memrlimit-add-memrlimit-controller-accounting-and-control-mm_owner-fix +++ a/mm/memrlimitcgroup.c @@ -207,17 +207,23 @@ static void memrlimit_cgroup_mm_owner_ch struct mm_struct *mm = get_task_mm(p); BUG_ON(!mm); - memrcg = memrlimit_cgroup_from_cgrp(cgrp); - old_memrcg = memrlimit_cgroup_from_cgrp(old_cgrp); /* * If we don't have a new cgroup, we just uncharge from the old one. * It means that the task is going away */ - if (memrcg && - res_counter_charge(&memrcg->as_res, (mm->total_vm << PAGE_SHIFT))) - goto out; - res_counter_uncharge(&old_memrcg->as_res, (mm->total_vm << PAGE_SHIFT)); + if (cgrp) { + memrcg = memrlimit_cgroup_from_cgrp(cgrp); + if (res_counter_charge(&memrcg->as_res, + mm->total_vm << PAGE_SHIFT)) + goto out; + } + + if (old_cgrp) { + old_memrcg = memrlimit_cgroup_from_cgrp(old_cgrp); + res_counter_uncharge(&old_memrcg->as_res, + mm->total_vm <