From: Frederic Weisbecker <fweisbec@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Paul Menage <paul@paulmenage.org>, Li Zefan <lizf@cn.fujitsu.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Aditya Kali <adityakali@google.com>,
Oleg Nesterov <oleg@redhat.com>,
Kay Sievers <kay.sievers@vrfy.org>,
Tim Hockin <thockin@hockin.org>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH 08/12] cgroups: Pull up res counter charge failure interpretation to caller
Date: Fri, 9 Sep 2011 15:33:20 +0200 [thread overview]
Message-ID: <20110909133316.GB14072@somewhere.redhat.com> (raw)
In-Reply-To: <20110906152650.a2f33bbd.akpm@linux-foundation.org>
On Tue, Sep 06, 2011 at 03:26:50PM -0700, Andrew Morton wrote:
> On Tue, 6 Sep 2011 02:13:02 +0200
> Frederic Weisbecker <fweisbec@gmail.com> wrote:
>
> > res_counter_charge() always returns -ENOMEM when the limit is reached
> > and the charge thus can't happen.
> >
> > However it's up to the caller to interpret this failure and return
> > the appropriate error value. The task counter subsystem will need
> > to report the user that a fork() has been cancelled because of some
> > limit reached, not because we are too short on memory.
> >
> > Fix this by returning -1 when res_counter_charge() fails.
> >
> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > Cc: Paul Menage <paul@paulmenage.org>
> > Cc: Li Zefan <lizf@cn.fujitsu.com>
> > Cc: Johannes Weiner <hannes@cmpxchg.org>
> > Cc: Aditya Kali <adityakali@google.com>
> > Cc: Oleg Nesterov <oleg@redhat.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Kay Sievers <kay.sievers@vrfy.org>
> > Cc: Tim Hockin <thockin@hockin.org>
> > Cc: Tejun Heo <tj@kernel.org>
> > ---
> > kernel/res_counter.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> > index 4aaa790..45fa6fb 100644
> > --- a/kernel/res_counter.c
> > +++ b/kernel/res_counter.c
> > @@ -26,7 +26,7 @@ int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
> > {
> > if (counter->usage + val > counter->limit) {
> > counter->failcnt++;
> > - return -ENOMEM;
> > + return -1;
> > }
> >
> > counter->usage += val;
>
> This also affects the return value of your new and undocumented
> res_counter_charge_until().
>
> That's a bit of a hand-grenade which could lead to system calls
> returning -1 (ie: EPERM) to userspace.
Right. What about making it a boolean?
next prev parent reply other threads:[~2011-09-09 13:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-06 0:12 [PATCH 00/12 v4][RESEND] cgroups: Task counter subsystem Frederic Weisbecker
2011-09-06 0:12 ` [PATCH 01/12] cgroups: Add res_counter_write_u64() API Frederic Weisbecker
2011-09-06 0:12 ` [PATCH 02/12] cgroups: New resource counter inheritance API Frederic Weisbecker
2011-09-06 22:17 ` Andrew Morton
2011-09-08 13:25 ` Frederic Weisbecker
2011-09-06 0:12 ` [PATCH 03/12] cgroups: Add previous cgroup in can_attach_task/attach_task callbacks Frederic Weisbecker
2011-09-06 0:12 ` [PATCH 04/12] cgroups: New cancel_attach_task subsystem callback Frederic Weisbecker
2011-09-06 0:12 ` [PATCH 05/12] cgroups: Ability to stop res charge propagation on bounded ancestor Frederic Weisbecker
2011-09-06 0:13 ` [PATCH 06/12] cgroups: Add res counter common ancestor searching Frederic Weisbecker
2011-09-06 22:21 ` Andrew Morton
2011-09-09 12:31 ` Frederic Weisbecker
2011-09-06 0:13 ` [PATCH 07/12] res_counter: Allow charge failure pointer to be null Frederic Weisbecker
2011-09-06 0:13 ` [PATCH 08/12] cgroups: Pull up res counter charge failure interpretation to caller Frederic Weisbecker
2011-09-06 22:26 ` Andrew Morton
2011-09-09 13:33 ` Frederic Weisbecker [this message]
2011-09-09 15:17 ` Andrew Morton
2011-09-06 0:13 ` [PATCH 09/12] cgroups: Add a task counter subsystem Frederic Weisbecker
2011-09-06 22:40 ` Andrew Morton
2011-09-13 15:13 ` Frederic Weisbecker
2011-09-06 0:13 ` [PATCH 10/12] cgroups: Add documentation for " Frederic Weisbecker
2011-09-06 22:41 ` Andrew Morton
2011-09-13 17:35 ` Frederic Weisbecker
2011-09-06 0:13 ` [RFC PATCH 11/12] cgroups: Allow subsystems to cancel a fork Frederic Weisbecker
2011-09-15 21:09 ` Andrew Morton
2011-10-01 15:29 ` Frederic Weisbecker
2011-09-06 0:13 ` [RFC PATCH 12/12] cgroups: Convert task counter to use the subsys fork callback Frederic Weisbecker
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