[libvirt] [PATCH] Don't fail lxc domain start when memory controller support is missing

[Guido Günther]

On Mon, Oct 18, 2010 at 10:11:51AM +0100, Daniel P. Berrange wrote:
> On Fri, Oct 15, 2010 at 06:05:10PM +0200, Guido Günther wrote:
> > On Fri, Oct 15, 2010 at 10:15:02AM +0200, Guido Günther wrote:
> > > Hi,
> > > starting of lxc domains currently fails if memory controller support is
> > > disabled in the kernel. Attached patch fixes this by ignoring the error
> > > in case the files don't exist in the cgroup filesystem. I didn't add the
> > > same exceptions for the recent hard and soft limit code since if somebody
> > > sets this values he probably wants them enforced. O.k. to apply?
> > In fact I missed one hunk. Here's a better patch with some commnents.
> >  -- Guido
> 
> > >From b0f6c1628a3654c8a49382cd5b29577fddfe3f1c Mon Sep 17 00:00:00 2001
> > From: =?UTF-8?q?Guido=20G=C3=BCnther?= <agx at sigxcpu.org>
> > Date: Fri, 15 Oct 2010 10:01:38 +0200
> > Subject: [PATCH] Don't fail lxc domain start when memory controller support is missing
> > 
> > Debian stock kernel has CONFIG_CGROUP_MEM_RES_CTLR disabled due to the
> > overhead [1]. Allow to start containers if the corresponding files in
> > the cgroup filesystem are missing. This fixes Debian bug #566180 [2].
> > 
> > [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=534964
> > [2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=566180
> > ---
> >  src/lxc/lxc_controller.c |    4 +++-
> >  src/lxc/lxc_driver.c     |   11 ++++++++---
> >  2 files changed, 11 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
> > index 20616b8..2a4f113 100644
> > --- a/src/lxc/lxc_controller.c
> > +++ b/src/lxc/lxc_controller.c
> > @@ -107,7 +107,9 @@ static int lxcSetContainerResources(virDomainDefPtr def)
> >          virReportSystemError(-rc,
> >                               _("Unable to set memory limit for domain %s"),
> >                               def->name);
> > -        goto cleanup;
> > +        /* Don't fail if we can't set memory due to lack of kernel support */
> > +        if (rc != -ENOENT)
> > +            goto cleanup;
> >      }
> >  
> >      if(def->mem.hard_limit) {
> > diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
> > index df814da..8085169 100644
> > --- a/src/lxc/lxc_driver.c
> > +++ b/src/lxc/lxc_driver.c
> > @@ -485,7 +485,7 @@ static int lxcDomainGetInfo(virDomainPtr dom,
> >      lxc_driver_t *driver = dom->conn->privateData;
> >      virDomainObjPtr vm;
> >      virCgroupPtr cgroup = NULL;
> > -    int ret = -1;
> > +    int ret = -1, rc;
> >  
> >      lxcDriverLock(driver);
> >      vm = virDomainFindByUUID(&driver->domains, dom->uuid);
> > @@ -515,10 +515,15 @@ static int lxcDomainGetInfo(virDomainPtr dom,
> >                       "%s", _("Cannot read cputime for domain"));
> >              goto cleanup;
> >          }
> > -        if (virCgroupGetMemoryUsage(cgroup, &(info->memory)) < 0) {
> > +        if ((rc = virCgroupGetMemoryUsage(cgroup, &(info->memory))) < 0) {
> >              lxcError(VIR_ERR_OPERATION_FAILED,
> >                       "%s", _("Cannot read memory usage for domain"));
> > -            goto cleanup;
> > +            if (rc == -ENOENT) {
> > +                /* Don't fail if we can't read memory usage due to a lack of
> > +                 * kernel support */
> > +                info->memory = 0;
> > +            } else
> > +                goto cleanup;
> >          }
> >      }
> 
> ACK
Pushed now. Thanks,
 -- Guido