Re: [patch 7/7 -mm] oom: remove unnecessary code and cleanup

KOSAKI Motohiro
2010-02-15T08:31:44Z

> On Fri, 12 Feb 2010, KAMEZAWA Hiroyuki wrote:
>
> > > Remove the redundancy in __oom_kill_task() since:
> > >
> > > - init can never be passed to this function: it will never be PF_EXITING
> > > or selectable from select_bad_process(), and
> > >
> > > - it will never be passed a task from oom_kill_task() without an ->mm
> > > and we're unconcerned about detachment from exiting tasks, there's no
> > > reason to protect them against SIGKILL or access to memory reserves.
> > >
> > > Also moves the kernel log message to a higher level since the verbosity
> > > is not always emitted here; we need not print an error message if an
> > > exiting task is given a longer timeslice.
> > >
> > > Signed-off-by: David Rientjes <rientjes@google.com>
> >
> > If you say "never", it's better to add BUG_ON() rather than
> > if (!p->mm)...
> >
>
> As the description says, oom_kill_task() never passes __oom_kill_task() a
> task, p, where !p->mm, but it doesn't imply that p cannot detach its ->mm
> before __oom_kill_task() gets a chance to run. The point is that we don't
> really care about giving it access to memory reserves anymore since it's
> exiting and won't be allocating anything. Warning about that scenario is
> unnecessary and would simply spam the kernel log, a recall to the oom
> killer would no longer select this task in case the oom condition persists
> anyway.

I agree this description is correct and this code is unnecessary.
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

>
> > But yes, this patch seesm to remove unnecessary codes.
> > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> >
>
> Thanks!
>
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