From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandru Copot Subject: [PATCH] virtio: suppress kmemleak false positive Date: Fri, 18 Jan 2013 13:54:21 +0200 Message-ID: <1358510061-12164-1-git-send-email-alex.mihai.c@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: rusty@rustcorp.com.au Cc: Daniel Baluta , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mst@redhat.com List-Id: virtualization@lists.linuxfoundation.org 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: [] kmemleak_alloc+0x21/0x50 [] __kmalloc+0xe0/0x160 [] virtqueue_add_buf+0x1fc/0x3d0 [] start_xmit+0x153/0x3a0 [] dev_hard_start_xmit+0x21e/0x470 [] sch_direct_xmit+0xfe/0x280 [] dev_queue_xmit+0x1f4/0x5d0 [] ip6_finish_output2+0x101/0x450 [] ip6_finish_output+0x98/0x200 [] ip6_output+0x51/0x1b0 [] mld_sendpack+0x19f/0x360 [] mld_ifc_timer_expire+0x194/0x290 [] call_timer_fn+0x74/0xf0 [] run_timer_softirq+0x18b/0x220 [] __do_softirq+0xe1/0x1c0 [] 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 CC: Daniel Baluta --- 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 #include #include +#include /* 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