On Wed, 2010-02-17 at 01:23 -0800, David Rientjes wrote: > On Wed, 17 Feb 2010, Minchan Kim wrote: > > > >> Okay. I can think it of slight penalization in this patch. > > >> But in current OOM logic, we try to kill child instead of forkbomb > > >> itself. My concern was that. > > > > > > We still do with my rewrite, that is handled in oom_kill_process(). The > > > forkbomb penalization takes place in badness(). > > > > > > I thought this patch is closely related to [patch 2/7]. > > I can move this discussion to [patch 2/7] if you want. > > Another guys already pointed out why we care child. > > > > We have _always_ tried to kill a child of the selected task first if it > has a seperate address space, patch 2 doesn't change that. It simply > tries to kill the child with the highest badness() score. So I mentioned following as. "Of course, It's not a part of your patch[2/7] which is good. It has been in there during long time. I hope we could solve that in this chance." > > > I said this scenario is BUGGY forkbomb process. It will fork + exec continuously > > if it isn't killed. How does user intervene to fix the system? > > System was almost hang due to unresponsive. > > > > The user would need to kill the parent if it should be killed. The > unresponsiveness in this example, however, is not a question of the oom > killer but rather the scheduler to provide interactivity to the user in > forkbomb scenarios. The oom killer should not create a policy that > unfairly biases tasks that fork a large number of tasks, however, to > provide interactivity since that task may be a vital system resource. As you said, scheduler(or something) can do it with much graceful than OOM killer. I agreed that. You wrote "Forkbomb detector" in your patch description. When I saw that, I thought we need more things to complete forkbomb detection. So I just suggested my humble idea to fix it in this chance. > > > For extreme example, > > User is writing some important document by OpenOffice and > > he decided to execute hackbench 1000000 process 1000000. > > > > Could user save his important office data without halt if we kill > > child continuously? > > I think this scenario can be happened enough if the user didn't know > > parameter of hackbench. > > > > So what exactly are you proposing we do in the oom killer to distinguish > between a user's mistake and a vital system resource? I'm personally much > more concerned with protecting system daemons that provide a service under > heavyload than protecting against forkbombs in the oom killer. I don't opposed that. As I said, I just wanted for OOM killer to be more smart to catch user's mistake. If I understand your opinion, You said, it's not role of OOM killer but scheduler. Okay. -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>