This is a Linux Dom0 crash on x86 (Dell PowerEdge R320, Xeon E5-2450),
CC'ing relevant people. As you can see from the links below the crash
is:

[ 253.619326] Call Trace:
[ 253.619330] <IRQ>
[ 253.619332] [<ffffffff815d7c25>] ? skb_copy_ubufs+0xa5/0x230
[ 253.619347] [<ffffffff815e8525>] __netif_receive_skb_core+0x6f5/0x940
[ 253.619353] [<ffffffff815e8788>] __netif_receive_skb+0x18/0x60
[ 253.619360] [<ffffffff815e87f8>] netif_receive_skb_internal+0x28/0x90
[ 253.619366] [<ffffffff815e91f5>] napi_gro_frags+0x125/0x1a0
[ 253.619378] [<ffffffffa01b1173>] mlx4_en_process_rx_cq+0x753/0xb50 [mlx4_en]
[ 253.619387] [<ffffffffa01b1657>] mlx4_en_poll_rx_cq+0x97/0x160 [mlx4_en]
[ 253.619393] [<ffffffff815e8bcd>] net_rx_action+0x13d/0x2f0
[ 253.619400] [<ffffffff8109fdea>] __do_softirq+0xda/0x1f0
[ 253.619406] [<ffffffff810a013d>] irq_exit+0x9d/0xb0
[ 253.619412] [<ffffffff813e3825>] xen_evtchn_do_upcall+0x35/0x50
[ 253.619420] [<ffffffff816c7bce>] xen_do_hypervisor_callback+0x1e/0x40
[ 253.619423] <EOI>
[ 253.619426] [<ffffffff811a7870>] ? shrink_dcache_for_umount+0x90/0x90
[ 253.619437] [<ffffffff811a7ad9>] ? d_alloc_pseudo+0x9/0x10
[ 253.619443] [<ffffffff815cbbed>] ? sock_alloc_file+0x4d/0x120
[ 253.619448] [<ffffffff815cdf78>] ? SYSC_accept4+0xb8/0x200
[ 253.619454] [<ffffffff811d0377>] ? SyS_epoll_wait+0x87/0xe0
[ 253.619459] [<ffffffff815cf5c9>] ? SyS_accept4+0x9/0x10
[ 253.619465] [<ffffffff816c630d>] ? system_call_fastpath+0x16/0x1b
[ 253.619469] Code: 4e 48 83 c4 08 5b 5d c3 66 0f 1f 44 00 00 e8 6b fc
ff ff eb e1 90 90 90 90 90 90 90 90 90 48 89 f8 48 89 d1 48 c1 e9 03 83
e2 07 <f3
> 48 a5 89 d1 f3 a4 c3 20 4c 8b 06 4c 8b 4e 08 4c 8b 56 10 4c
[ 253.619513] RIP [<ffffffff81318b0d>] __memcpy+0xd/0x110
[ 253.619520] RSP <ffff88006b823c60>
[ 253.619524] ---[ end trace ba5d35a466b03856 ]---

On Tue, 28 Jul 2015, Christoffer Dall wrote:
> On Tue, Jul 28, 2015 at 4:55 PM, Ian Campbell <ian.campbell@citrix.com> wrote:
>       On Tue, 2015-07-28 at 10:50 -0400, Konrad Rzeszutek Wilk wrote:
>       > On Tue, Jul 28, 2015 at 03:09:31PM +0200, Christoffer Dall wrote:
>       > > Hi,
>       > >
>       > > I've been doing some performance comparisons lately, and wanted to
>       > > compare
>       > > the performance overhead of using Xen with apache bench, but
>       > > unfortunately
>       > > the Dom0 kernel crashes when hitting it with ab from a remote machine.
>       > > Most other workloads seem to be stable, however, I do see similar
>       > > crashes
>       > > if hitting Dom0 mysql with a mysql benchmark with a high level of
>       > > parallelism.
>       > >
>       > > I use a 10G Mellanox MX354A Dual port FDR CX3 adapter for networking on
>       > > a
>       > > Dell PowerEdge R320 system with a Xeon E5-2450 and 16 GB of RAM.
>       > >
>       > > Interestingly, we had a similarly looking issue on arm64 recently, but
>       > > that
>       > > was fixed with an APM-soecific fix to the hypervisor, so I am guessing
>       > > this
>       > > is unrelated, see:
>       > > http://lists.xenproject.org/archives/html/xen-devel/2015
>       > > -03/msg02731.html
>       > > and the fix:
>       > > http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=50dcb3de603927db2fd
>       > > 87ba09e29c817415aaa44
>       > >
>       > > I have tried with several Linux versions, v3.13, v3.18, v4.0-rc4, and
>       > > v4.1,
>       > > same issue.  I have tried with Xen 4.5-0 release, and the Ubuntu
>       > > packaged
>       > > Xen 4.4 release, same issue.
>       > >
>       > > Examples of crash:
>       > > http://pastebin.ubuntu.com/11953498/
>       > > http://pastebin.ubuntu.com/11953443/
>       >
>       > 4.0-rc4?
>       >
>       > Have you tried 4.1?
>
> According to the previous paragraph, yes he has.
>
> yes, I have.  Just for clarify, I used 4.0-rc4 because that's a branch which contained arm64 PCI support and has
> been used for other measurements, so this was simply my 'working tree'.