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 <alex.mihai.c at gmail.com>
CC: Daniel Baluta <dbaluta at ixiacom.com>
---
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);
/* Transfer entries from the sg list into the indirect page */
for (i = 0; i < out; i++) {
--
1.8.1
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 <alex.mihai.c at gmail.com> > CC: Daniel Baluta <dbaluta at ixiacom.com> > --- > 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. -- Catalin
On Fri, Jan 11, 2013 at 4:02 PM, Catalin Marinas <catalin.marinas at arm.com>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 <alex.mihai.c at gmail.com> > > CC: Daniel Baluta <dbaluta at ixiacom.com> > > --- > > 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 C?t?lin. 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20130111/4dc9bb65/attachment-0001.html>
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 <alex.mihai.c at gmail.com>
CC: Daniel Baluta <dbaluta at ixiacom.com>
---
drivers/virtio/virtio_ring.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index ffd7e7d..730baa4 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. */
@@ -141,6 +142,11 @@ static int vring_add_indirect(struct vring_virtqueue *vq,
if (!desc)
return -ENOMEM;
+ /* This pointer is passed below by its physical address so
+ * kmemleak would show a false positive without it.
+ */
+ kmemleak_not_leak(desc);
+
/* Transfer entries from the sg list into the indirect page */
for (i = 0; i < out; i++) {
desc[i].flags = VRING_DESC_F_NEXT;
--
1.8.1