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    SubjectRe: Memory overcommit
    On Wed, 28 Oct 2009 11:47:55 +0900 (JST)
    KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

    > > 2. I started out running my mlock test program as root (later
    > > switched to use "ulimit -l unlimited" first). But badness() reckons
    > > CAP_SYS_ADMIN or CAP_SYS_RESOURCE is a reason to quarter your points;
    > > and CAP_SYS_RAWIO another reason to quarter your points: so running
    > > as root makes you sixteen times less likely to be killed. Quartering
    > > is anyway debatable, but sixteenthing seems utterly excessive to me.
    > >
    > > I moved the CAP_SYS_RAWIO test in with the others, so it does no
    > > more than quartering; but is quartering appropriate anyway? I did
    > > wonder if I was right to be "subverting" the fine-grained CAPs in
    > > this way, but have since seen unrelated mail from one who knows
    > > better, implying they're something of a fantasy, that su and sudo
    > > are indeed what's used in the real world. Maybe this patch was okay.
    >
    > I agree quartering is debatable.
    > At least, killing quartering is worth for any user, and it can be push into -stable.
    >
    >
    >
    >
    > From 27331555366c908a93c2cdd780b77e421869c5af Mon Sep 17 00:00:00 2001
    > From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    > Date: Wed, 28 Oct 2009 11:28:39 +0900
    > Subject: [PATCH] oom: Mitigate suer-user's bonus of oom-score
    >
    > Currently, badness calculation code of oom contemplate following bonus.
    > - Super-user have quartering oom-score
    > - CAP_SYS_RAWIO process (e.g. database) also have quartering oom-score
    >
    > The problem is, Super-users have CAP_SYS_RAWIO too. Then, they have
    > sixteenthing bonus. it's obviously too excessive and meaningless.
    >
    > This patch fixes it.
    >
    > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

    I'll pick this up to my series.

    Thanks,
    -Kame

    > ---
    > mm/oom_kill.c | 13 +++++--------
    > 1 files changed, 5 insertions(+), 8 deletions(-)
    >
    > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
    > index ea2147d..40d323d 100644
    > --- a/mm/oom_kill.c
    > +++ b/mm/oom_kill.c
    > @@ -152,18 +152,15 @@ unsigned long badness(struct task_struct *p, unsigned long uptime)
    > /*
    > * Superuser processes are usually more important, so we make it
    > * less likely that we kill those.
    > - */
    > - if (has_capability_noaudit(p, CAP_SYS_ADMIN) ||
    > - has_capability_noaudit(p, CAP_SYS_RESOURCE))
    > - points /= 4;
    > -
    > - /*
    > - * We don't want to kill a process with direct hardware access.
    > + *
    > + * Plus, We don't want to kill a process with direct hardware access.
    > * Not only could that mess up the hardware, but usually users
    > * tend to only have this flag set on applications they think
    > * of as important.
    > */
    > - if (has_capability_noaudit(p, CAP_SYS_RAWIO))
    > + if (has_capability_noaudit(p, CAP_SYS_ADMIN) ||
    > + has_capability_noaudit(p, CAP_SYS_RESOURCE) ||
    > + has_capability_noaudit(p, CAP_SYS_RAWIO))
    > points /= 4;
    >
    > /*
    > --
    > 1.6.2.5
    >
    >
    >
    >
    >



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