On Tue 27-09-11 11:51:00, Rusty Russell wrote: > On Mon, 26 Sep 2011 13:05:59 +0200, Michal Hocko <mhocko@xxxxxxx> wrote: > > On Mon 26-09-11 19:58:50, Rusty Russell wrote: > > > On Mon, 26 Sep 2011 10:28:37 +0200, Michal Hocko <mhocko@xxxxxxx> wrote: > > > > On Fri 26-08-11 11:13:40, David Rientjes wrote: > > > > > I'd love to be able to do a thaw on a PF_FROZEN task in the oom killer > > > > > followed by a SIGKILL if that task is selected for oom kill without an > > > > > heuristic change. Not sure if that's possible, so we'll wait for Rafael > > > > > to chime in. > > > > > > > > We have discussed that with Rafael and it should be safe to do that. See > > > > the patch bellow. > > > > The only place I am not entirely sure about is run_guest > > > > (drivers/lguest/core.c). It seems that the code is able to cope with > > > > signals but it also calls lguest_arch_run_guest after try_to_freeze. > > > > > > Yes; if you want to kill things in the refrigerator(), then will a > > > > > > if (cpu->lg->dead || task_is_dead(current)) > > > break; > > > > > > Work? > > > > The task is not dead yet. We should rather check for pending signals. > > Can we just move try_to_freeze up before the pending signals check? > > Yep, that works. > > Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Thanks. The full patch bellow: --- >From c8b4f49ad85948b7362c50964d6c09f0e35a6537 Mon Sep 17 00:00:00 2001 From: Michal Hocko <mhocko@xxxxxxx> Date: Tue, 27 Sep 2011 08:56:03 +0200 Subject: [PATCH] lguest: move process freezing before pending signals check run_guest tries to freeze the current process after it has handled pending interrupts and before it calls lguest_arch_run_guest. This doesn't work nicely if the task has been killed while being frozen and when we want to handle that signal as soon as possible. Let's move try_to_freeze before we check for pending signal so that we can get out of the loop as soon as possible. Signed-off-by: Michal Hocko <mhocko@xxxxxxx> Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> --- drivers/lguest/core.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 2535933..e7dda91 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -232,6 +232,13 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) } } + /* + * All long-lived kernel loops need to check with this horrible + * thing called the freezer. If the Host is trying to suspend, + * it stops us. + */ + try_to_freeze(); + /* Check for signals */ if (signal_pending(current)) return -ERESTARTSYS; @@ -246,13 +253,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) try_deliver_interrupt(cpu, irq, more); /* - * All long-lived kernel loops need to check with this horrible - * thing called the freezer. If the Host is trying to suspend, - * it stops us. - */ - try_to_freeze(); - - /* * Just make absolutely sure the Guest is still alive. One of * those hypercalls could have been fatal, for example. */ -- 1.7.5.4 -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>