Messages in this thread | | | Date | Fri, 11 Apr 2008 10:17:35 +0530 | From | Balbir Singh <> | Subject | Re: [-mm] Add an owner to the mm_struct (v9) |
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KAMEZAWA Hiroyuki wrote: > On Fri, 11 Apr 2008 09:57:06 +0530 > Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > >> KAMEZAWA Hiroyuki wrote: >>> maybe I don't undestand correctlly... >>> >>> On Thu, 10 Apr 2008 14:46:02 +0530 >>> Balbir Singh <balbir@linux.vnet.ibm.com> wrote: >>> >>>> >>>> +config MM_OWNER >>>> + bool >>>> + >>> no default is ok here ? what value will this have if not selected ? >>> I'm sorry if I misunderstand Kconfig. >>> >> The way this works is >> >> If I select memory resource controller, CONFIG_MM_OWNER is set to y, else it >> does not even show up in the .config >> > ok, sorry for noise. >
No problem at all, please feel free to question anything.
>>>> + /* >>>> + * Search through everything else. We should not get >>>> + * here often >>>> + */ >>>> + do_each_thread(g, c) { >>>> + if (c->mm == mm) >>>> + goto assign_new_owner; >>>> + } while_each_thread(g, c); >>>> + >>> Again, do_each_thread() is suitable here ? >>> for_each_process() ? >>> >> do_each_thread(), while_each_thread() walks all processes and threads of those >> processes in the system. It is a common pattern used in the kernel (see >> try_to_freeze_tasks() or oom_kill_task() for example). >> > > What you want is finding a thread which has the "mm_struct". Why search all > threads ? I think you only have to search processes(i.e. thread-group-leaders). > > try_to_freeze_tasks()/oom_kill_task() have to chase all threads because > it have to check flags in task_structs in a process. >
Good question. It is possible that clone() was called with CLONE_VM without CLONE_THREAD. In which case we have threads sharing the VM without a thread group leader. Please see zap_threads() for a similar search pattern.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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