On Fri, Jan 11, 2013 at 4:02 PM, Catalin Marinas <[email protected]>wrote:
> On Fri, Jan 11, 2013 at 01:51:43PM +0000, Alexandru Copot wrote: > > While doing simple IPv6 tests in KVM virtual machines, > > (add an IPv6 address to eth0) kmemleak complains about > > an unreferenced object: > > > > unreferenced object 0xffff88001e804120 (size 32): > > comm "softirq", pid 0, jiffies 4294900928 (age 631.544s) > > hex dump (first 32 bytes): > > 28 cb fd 1d 00 00 00 00 0c 00 00 00 01 00 01 00 (............... > > 02 d0 83 1d 00 00 00 00 6e 00 00 00 00 00 00 00 ........n....... > > backtrace: > > [<ffffffff815ed721>] kmemleak_alloc+0x21/0x50 > > [<ffffffff8111d0b0>] __kmalloc+0xe0/0x160 > > [<ffffffff81362b7c>] virtqueue_add_buf+0x1fc/0x3d0 > > [<ffffffff8140cbd3>] start_xmit+0x153/0x3a0 > > [<ffffffff8150887e>] dev_hard_start_xmit+0x21e/0x470 > > [<ffffffff815247ce>] sch_direct_xmit+0xfe/0x280 > > [<ffffffff81509014>] dev_queue_xmit+0x1f4/0x5d0 > > [<ffffffff81592e91>] ip6_finish_output2+0x101/0x450 > > [<ffffffff81595ae8>] ip6_finish_output+0x98/0x200 > > [<ffffffff81595ca1>] ip6_output+0x51/0x1b0 > > [<ffffffff815b51af>] mld_sendpack+0x19f/0x360 > > [<ffffffff815b59b4>] mld_ifc_timer_expire+0x194/0x290 > > [<ffffffff8104b794>] call_timer_fn+0x74/0xf0 > > [<ffffffff8104bb1b>] run_timer_softirq+0x18b/0x220 > > [<ffffffff81045f81>] __do_softirq+0xe1/0x1c0 > > [<ffffffff8160a4fc>] call_softirq+0x1c/0x30 > > > > Seems the function vring_add_indirect stores an array of > > struct vring_desc by using virt_to_phys and kmemleak > > doesn't track the pointer. > > > > The following patch can fix this. > > > > Signed-off-by: Alexandru Copot <[email protected]> > > CC: Daniel Baluta <[email protected]> > > --- > > drivers/virtio/virtio_ring.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index ffd7e7d..e0b591b 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -23,6 +23,7 @@ > > #include <linux/slab.h> > > #include <linux/module.h> > > #include <linux/hrtimer.h> > > +#include <linux/kmemleak.h> > > > > /* virtio guest is communicating with a virtual "device" that actually > runs on > > * a host processor. Memory barriers are used to control SMP effects. > */ > > @@ -140,6 +141,7 @@ static int vring_add_indirect(struct vring_virtqueue > *vq, > > desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); > > if (!desc) > > return -ENOMEM; > > + kmemleak_not_leak(desc); > > Please add a comment above this call in case people later wonder why > this annotation is needed. > > Thanks Cătălin. So, kememleak cannot handle this kind of pointer aliases? Also, I wonder if phys_to_virt(virt_to_phys(x)) == x holds true all the time. thanks, Daniel.
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