From: David Miller <davem@davemloft.net>
To: vkuznets@redhat.com
Cc: netdev@vger.kernel.org, devel@linuxdriverproject.org,
linux-kernel@vger.kernel.org, kys@microsoft.com,
haiyangz@microsoft.com
Subject: Re: [PATCH net] hv_netvsc: Restore needed_headroom request
Date: Sat, 13 Feb 2016 06:05:07 -0500 (EST) [thread overview]
Message-ID: <20160213.060507.1405887572923400829.davem@davemloft.net> (raw)
In-Reply-To: <1454689748-29095-1-git-send-email-vkuznets@redhat.com>
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 5 Feb 2016 17:29:08 +0100
> Commit c0eb454034aa ("hv_netvsc: Don't ask for additional head room in the
> skb") got rid of needed_headroom setting for the driver. With the change I
> hit the following issue trying to use ptkgen module:
>
> [ 57.522021] kernel BUG at net/core/skbuff.c:1128!
> [ 57.522021] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
> ...
> [ 58.721068] Call Trace:
> [ 58.721068] [<ffffffffa0144e86>] netvsc_start_xmit+0x4c6/0x8e0 [hv_netvsc]
> ...
> [ 58.721068] [<ffffffffa02f87fc>] ? pktgen_finalize_skb+0x25c/0x2a0 [pktgen]
> [ 58.721068] [<ffffffff814f5760>] ? __netdev_alloc_skb+0xc0/0x100
> [ 58.721068] [<ffffffffa02f9907>] pktgen_thread_worker+0x257/0x1920 [pktgen]
>
> Basically, we're calling skb_cow_head(skb, RNDIS_AND_PPI_SIZE) and crash on
> if (skb_shared(skb))
> BUG();
>
> We probably need to restore needed_headroom setting (but shrunk to
> RNDIS_AND_PPI_SIZE as we don't need more) to request the required headroom
> space. In theory, it should not give us performance penalty.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Applied, thanks.
prev parent reply other threads:[~2016-02-13 11:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-05 16:29 Vitaly Kuznetsov
2016-02-10 10:05 ` Vitaly Kuznetsov
2016-02-10 11:14 ` David Miller
2016-02-13 11:05 ` David Miller [this message]
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