RE: ARM64/KVM: Bad page state in process iperf

[Bhushan Bharat]

> -----Original Message-----
> From: Marc Zyngier [mailto:marc.zyngier@xxxxxxx]
> Sent: Tuesday, December 15, 2015 3:50 PM
> To: Bhushan Bharat-R65777 <Bharat.Bhushan@xxxxxxxxxxxxx>;
> kvmarm@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: ARM64/KVM: Bad page state in process iperf
> 
> On 15/12/15 09:53, Bhushan Bharat wrote:
> > Hi Mark,
> >
> >> -----Original Message-----
> >> From: Marc Zyngier [mailto:marc.zyngier@xxxxxxx]
> >> Sent: Tuesday, December 15, 2015 3:05 PM
> >> To: Bhushan Bharat-R65777 <Bharat.Bhushan@xxxxxxxxxxxxx>;
> >> kvmarm@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux-arm-
> >> kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> >> Subject: Re: ARM64/KVM: Bad page state in process iperf
> >>
> >> On 15/12/15 03:46, Bhushan Bharat wrote:
> >>>
> >>> Hi All,
> >>>
> >>> I am running "iperf" in KVM guest on ARM64 machine and observing
> >>> below
> >> crash.
> >>>
> >>> =============================
> >>> $iperf -c 3.3.3.3 -P 4 -t 0 -i 5 -w 90k
> >>> ------------------------------------------------------------
> >>> Client connecting to 3.3.3.3, TCP port 5001 TCP window size:  180
> >>> KByte (WARNING: requested 90.0 KByte)
> >>> ------------------------------------------------------------
> >>> [  3] local 3.3.3.1 port 51131 connected with 3.3.3.3 port 5001 [
> >>> 6] local 3.3.3.1 port 51134 connected with 3.3.3.3 port 5001 [  5]
> >>> local
> >>> 3.3.3.1 port 51133 connected with 3.3.3.3 port 5001 [  4] local
> >>> 3.3.3.1 port 51132 connected with 3.3.3.3 port 5001
> >>> [   53.088567] random: nonblocking pool is initialized
> >>> [ ID] Interval       Transfer     Bandwidth
> >>> [  3]  0.0- 5.0 sec   638 MBytes  1.07 Gbits/sec
> >>> [  4] 35.0-40.0 sec  1.66 GBytes  2.85 Gbits/sec [  5] 40.0-45.0 sec
> >>> 1.11 GBytes  1.90 Gbits/sec [  4] 40.0-45.0 sec  1.16 GBytes  1.99
> >>> Gbits/sec
> >>> [   98.895207] BUG: Bad page state in process iperf  pfn:0a584
> >>> [   98.896164] page:ffff780000296100 count:-1 mapcount:0 mapping:
> >> (null) index:0x0
> >>> [   98.897436] flags: 0x0()
> >>> [   98.897885] page dumped because: nonzero _count
> >>> [   98.898640] Modules linked in:
> >>> [   98.899178] CPU: 0 PID: 1639 Comm: iperf Not tainted 4.1.8-00461-
> >> ge5431ad #141
> >>> [   98.900302] Hardware name: linux,dummy-virt (DT)
> >>> [   98.901014] Call trace:
> >>> [   98.901406] [<ffff800000096cac>] dump_backtrace+0x0/0x12c
> >>> [   98.902522] [<ffff800000096de8>] show_stack+0x10/0x1c
> >>> [   98.903441] [<ffff800000678dc8>] dump_stack+0x8c/0xdc
> >>> [   98.904202] [<ffff800000145480>] bad_page+0xc4/0x114
> >>> [   98.904945] [<ffff8000001487a4>]
> get_page_from_freelist+0x590/0x63c
> >>> [   98.905871] [<ffff80000014893c>]
> __alloc_pages_nodemask+0xec/0x794
> >>> [   98.906791] [<ffff80000059fc80>] skb_page_frag_refill+0x70/0xa8
> >>> [   98.907678] [<ffff80000059fcd8>] sk_page_frag_refill+0x20/0xd0
> >>> [   98.908550] [<ffff8000005edc04>] tcp_sendmsg+0x1f8/0x9a8
> >>> [   98.909368] [<ffff80000061419c>] inet_sendmsg+0x5c/0xd0
> >>> [   98.910178] [<ffff80000059bb44>] sock_sendmsg+0x14/0x58
> >>> [   98.911027] [<ffff80000059bbec>] sock_write_iter+0x64/0xbc
> >>> [   98.912119] [<ffff80000019b5b8>] __vfs_write+0xac/0x10c
> >>> [   98.913126] [<ffff80000019bcb8>] vfs_write+0x90/0x1a0
> >>> [   98.913963] [<ffff80000019c53c>] SyS_write+0x40/0xa0
> >>
> >> This looks quite bad, but I don't see anything here that links it to
> >> KVM (apart from being a guest). Do you have any indication that this
> >> is due to KVM misbehaving?
> >
> > I never observed this issue in host Linux but observed this issue always in
> guest Linux. This issue does not comes immediately after I run "iperf" but
> after some time.
> >
> >> I'd appreciate a few more details.
> >
> > We have a networking hardware and we are directly assigning the h/w to
> guest. When using the same networking hardware in host it always works as
> expected (tried 100s of times).
> > Also this issue is not observed when we have only one vCPU in guest but
> seen when we have SMP guest.
> 
> Can you reproduce the same issue without VFIO (using virtio, for example)?

With virtio I have not observed this issue.

> Is that platform VFIO? or PCI?

It is not vfio-pci and vfio-platform. It is vfio-fls-mc (some Freescale new hardware), similar to the lines of vfio-platform uses same set of VFIO APIs used by vfio-pci/platform. Do you think this can be some h/w specific issue.

Thanks
-Bharat

> 
> Thanks,
> 
> 	M.
> --
> Jazz is not dead. It just smells funny...
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