> On Tue, Apr 26, 2011 at 2:38 PM, KOSAKI Motohiro > <[email protected]> wrote: > >> When memory pressure is high, virtio ballooning will probably cause oom > >> killing. > >> Even if alloc_page with GFP_NORETRY itself does not directly trigger oom it > >> will make memory becoming low then memory alloc of other processes will > >> trigger > >> oom killing. It is not desired behaviour. > >> > >> Here disable oom killer in fill_balloon to address this issue. > >> > >> Signed-off-by: Dave Young <[email protected]> > >> --- > >> drivers/virtio/virtio_balloon.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> --- linux-2.6.orig/drivers/virtio/virtio_balloon.c 2010-10-13 > >> 10:14:38.000000000 +0800 > >> +++ linux-2.6/drivers/virtio/virtio_balloon.c 2011-04-26 > >> 11:38:43.979785141 +0800 > >> @@ -25,6 +25,7 @@ > >> #include <linux/freezer.h> > >> #include <linux/delay.h> > >> #include <linux/slab.h> > >> +#include <linux/oom.h> > >> > >> struct virtio_balloon > >> { > >> @@ -102,6 +103,7 @@ static void fill_balloon(struct virtio_b > >> /* We can only do one array worth at a time. */ > >> num = min(num, ARRAY_SIZE(vb->pfns)); > >> > >> + oom_killer_disable(); > > > > I think this patch need proper comment at least. My first impression > > is, "Hm, __GFP_NORETRY should prevent oom, why is this necessary?". > > So, this actually prevent _another_ thread call out_of_memory(). > > Thanks, will fix. > > > Also, Here doesn't have any exclusion against hibernation (ie another > > oom_killer_disable() callsite). It should be described why lock is > > unnecessary. > > Good catch, but lock should better be handled in oom_killer_disable > function itself, > What do you think? > > For oom killer multi user there's more problem, if process A disable > oom killer then Process B enable oom killer, it is not A want to see, > Any thoughts?
If baloon and hibernation don't have any implicit exclusion, you are right. Sorry, I don't virtio internal. please don't ask me. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
