linux-kernel - Re: [PATCH v2] virtio_balloon: disable oom killer when fill balloon

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20110427110838.D178.A69D9226@jp.fujitsu.com>
Date:	Wed, 27 Apr 2011 11:06:45 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Dave Young <hidave.darkstar@...il.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	Minchan Kim <minchan.kim@...il.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH v2] virtio_balloon: disable oom killer when fill balloon

> On Wed, Apr 27, 2011 at 9:37 AM, Dave Young <hidave.darkstar@...il.com> wrote:
> > On Wed, Apr 27, 2011 at 7:33 AM, Minchan Kim <minchan.kim@...il.com> wrote:
> >> On Tue, Apr 26, 2011 at 6:39 PM, Dave Young <hidave.darkstar@...il.com> wrote:
> >>> On Tue, Apr 26, 2011 at 5:28 PM, Minchan Kim <minchan.kim@...il.com> wrote:
> >>>> Please resend this with [2/2] to linux-mm.
> >>>>
> >>>> On Tue, Apr 26, 2011 at 5:59 PM, Dave Young <hidave.darkstar@...il.com> 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.
> >>>>
> >>>> I can't understand why it is undesirable.
> >>>> Why do we have to handle it specially?
> >>>>
> >>>
> >>> Suppose user run some random memory hogging process while ballooning
> >>> it will be undesirable.
> >>
> >>
> >> In VM POV, kvm and random memory hogging processes are customers.
> >> If we handle ballooning specially with disable OOM, what happens other
> >> processes requires memory at same time? Should they wait for balloon
> >> driver to release memory?
> >>
> >> I don't know your point. Sorry.
> >> Could you explain your scenario in detail for justify your idea?
> >
> > What you said make sense I understand what you said now. Lets ignore
> > my above argue and see what I'm actually doing.
> >
> > I'm hacking with balloon driver to fit to short the vm migration time.
> >
> > while migrating host tell guest to balloon as much memory as it can, then start
> > migrate, just skip the ballooned pages, after migration done tell
> > guest to release the memory.
> >
> > In migration case oom is not I want to see and disable oom will be good.
> 
> BTW, if oom_killer_disabled is really not recommended to use I can
> switch back to oom_notifier way.

Could you please explain why you dislike oom_notifier and what problem
you faced? I haven't understand why oom_notifier is bad. probably my
less knowledge of balloon is a reason.



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/