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From: Christoph Paasch <christoph.paasch@uclouvain.be>
To: virtualization@lists.linux-foundation.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Kmemleak: false-positive in vring_add_indirect ?
Date: Wed, 2 Oct 2013 22:20:47 +0200	[thread overview]
Message-ID: <20131002202047.GA7419@cpaasch-mac> (raw)

Hello,

I have been hunting a memory-leak warning in vring_add_indirect:

unreferenced object 0xffff88003d467e20 (size 32):
  comm "softirq", pid 0, jiffies 4295197765 (age 6.364s)
  hex dump (first 32 bytes):
    28 19 bf 3d 00 00 00 00 0c 00 00 00 01 00 01 00  (..=............
    02 dc 51 3c 00 00 00 00 56 00 00 00 00 00 00 00  ..Q<....V.......
  backtrace:
    [<ffffffff8152db19>] kmemleak_alloc+0x59/0xc0
    [<ffffffff81102e93>] __kmalloc+0xf3/0x180
    [<ffffffff812db5d6>] vring_add_indirect+0x36/0x280
    [<ffffffff812dc59f>] virtqueue_add_outbuf+0xbf/0x4e0
    [<ffffffff813a8b30>] start_xmit+0x1a0/0x3b0
    [<ffffffff81445861>] dev_hard_start_xmit+0x2d1/0x4d0
    [<ffffffff81460052>] sch_direct_xmit+0xf2/0x1c0
    [<ffffffff81445c28>] dev_queue_xmit+0x1c8/0x460
    [<ffffffff814e3187>] ip6_finish_output2+0x1d7/0x470
    [<ffffffff814e34b0>] ip6_finish_output+0x90/0xb0
    [<ffffffff814e3507>] ip6_output+0x37/0xb0
    [<ffffffff815021eb>] igmp6_send+0x2db/0x470
    [<ffffffff81502645>] igmp6_timer_handler+0x95/0xa0
    [<ffffffff8104b57c>] call_timer_fn+0x2c/0x90
    [<ffffffff8104b7ba>] run_timer_softirq+0x1da/0x1f0
    [<ffffffff81045721>] __do_softirq+0xd1/0x1b0

May it be that the allocated memory within vring_add_indirect should be marked
as kmemleak_ignore(), because it is mapped from a virtual to a physical
address and thus kmemleak cannot detect that the memory is actually still
being referenced.


Thanks for your help,
Christoph

             reply	other threads:[~2013-10-02 20:20 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-02 20:20 Christoph Paasch [this message]
2013-10-03 23:59 ` Kmemleak: false-positive in vring_add_indirect ? Rusty Russell
2013-10-04  7:23   ` Christoph Paasch
2013-10-07  9:22     ` Rusty Russell

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