Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1227065

Re: DEFINE_IDA causing memory leaks? (was Re: [PATCH 1/2] virtio: fix memory leak of virtio ida cache layers)

Show all headers | View raw

On Thu, 2015-09-17 at 08:33 +0300, Michael S. Tsirkin wrote:
> On Wed, Sep 16, 2015 at 07:29:17PM -0500, Suman Anna wrote:
> > The virtio core uses a static ida named virtio_index_ida for
> > assigning index numbers to virtio devices during registration.
> > The ida core may allocate some internal idr cache layers and
> > an ida bitmap upon any ida allocation, and all these layers are
> > truely freed only upon the ida destruction. The virtio_index_ida
> > is not destroyed at present, leading to a memory leak when using
> > the virtio core as a module and atleast one virtio device is
> > registered and unregistered.
> > 
> > Fix this by invoking ida_destroy() in the virtio core module
> > exit.
> > 
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Signed-off-by: Suman Anna <s-anna@ti.com>
> 
> Interesting.
> Will the same apply to e.g. sd_index_ida in drivers/scsi/sd.c
> or iscsi_sess_ida in drivers/scsi/scsi_transport_iscsi.c?
> 
> If no, why not?
> 
> One doesn't generally expect to have to free global variables.
> Maybe we should forbid DEFINE_IDA in modules?
> 
> James, could you comment on this please?

ida is Tejun's baby (cc'd).  However, it does look like without
ida_destroy() you will leave a cached ida->bitmap dangling because we're
trying to be a bit clever in ida_remove() so we cache the bitmap to
relieve ida_pre_get() of the burden if we would otherwise free it.

I don't understand why you'd want to forbid DEFINE_IDA ... all it does
is pre-initialise a usually static ida structure.  The initialised
structure will have a NULL bitmap cache that's allocated in the first
ida_pre_get() ... that all seems to work as expected and no different
from a dynamically allocated struct ida.  Or are you thinking because
ida_destory() doesn't set bitmap to NULL, it damages the reuse?  In
which case I'm not sure there's much benefit to making it reusable, but
I suppose we could by adding a memset into ida_destroy().

James

> > ---
> >  drivers/virtio/virtio.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > index b1877d73fa56..7062bb0975a5 100644
> > --- a/drivers/virtio/virtio.c
> > +++ b/drivers/virtio/virtio.c
> > @@ -412,6 +412,7 @@ static int virtio_init(void)
> >  static void __exit virtio_exit(void)
> >  {
> >  	bus_unregister(&virtio_bus);
> > +	ida_destroy(&virtio_index_ida);
> >  }
> >  core_initcall(virtio_init);
> >  module_exit(virtio_exit);
> > -- 
> > 2.5.0
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 




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

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/2] Fix memory leaks in virtio & remoteproc cores Suman Anna <s-anna@ti.com> - 2015-09-17 02:30 +0200
  [PATCH 2/2] remoteproc: fix memory leak of remoteproc ida cache layers Suman Anna <s-anna@ti.com> - 2015-09-17 02:30 +0200
  [PATCH 1/2] virtio: fix memory leak of virtio ida cache layers Suman Anna <s-anna@ti.com> - 2015-09-17 02:30 +0200
    DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio: fix  memory leak of virtio ida cache layers) "Michael S. Tsirkin" <mst@redhat.com> - 2015-09-17 07:40 +0200
      Re: DEFINE_IDA causing memory leaks? (was Re: [PATCH 1/2] virtio: fix  memory leak of virtio ida cache layers) Hannes Reinecke <hare@suse.de> - 2015-09-17 09:00 +0200
        Re: DEFINE_IDA causing memory leaks? (was Re: [PATCH 1/2] virtio: fix  memory leak of virtio ida cache layers) Suman Anna <s-anna@ti.com> - 2015-09-18 00:40 +0200
      Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-09-17 16:20 +0200
        Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) Tejun Heo <htejun@gmail.com> - 2015-09-17 17:20 +0200
        Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) "Michael S. Tsirkin" <mst@redhat.com> - 2015-09-17 18:10 +0200
          Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-09-17 18:50 +0200
            Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) Tejun Heo <htejun@gmail.com> - 2015-09-17 19:20 +0200
              Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) James Bottomley <James.Bottomley@HansenPartnership.com> - 2015-09-17 20:00 +0200
                Re: DEFINE_IDA causing memory leaks? (was  Re: [PATCH 1/2] virtio:  fix memory leak of virtio ida cache layers) Tejun Heo <htejun@gmail.com> - 2015-09-17 20:10 +0200

csiph-web