Re: [Xen-devel] 3.16-rc2 WARNING: CPU: 0 PID: 0 at arch/x86/xen/multicalls.c:129 xen_mc_flush+0x1ab/0x1c0()

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Jun 26, 2014 at 12:16:43PM -0400, Boris Ostrovsky wrote:
> On 06/26/2014 07:57 AM, Sander Eikelenboom wrote:
> >Hi,
> >
> >Got the warning below on dom0 boot with a 3.16-rc2 kernel, doesn't seem to do
> >much immediate harm:
> >
> >[   12.723393] Calibrating delay loop (skipped), value calculated using 
> >timer frequency.. 6402.05 BogoMIPS (lpj=10667280)
> >[   12.723414] pid_max: default: 32768 minimum: 301
> >[   12.723433] ACPI: Core revision 20140424
> >[   12.740681] ACPI: All ACPI Tables successfully acquired
> >[   12.743145] ------------[ cut here ]------------
> >[   12.743170] WARNING: CPU: 0 PID: 0 at arch/x86/xen/multicalls.c:129 
> >xen_mc_flush+0x1ab/0x1c0()
> >[   12.743186] Modules linked in:
> >[   12.743196] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 
> >3.16.0-rc2-20140626+ #1
> >[   12.743209] Hardware name: MSI MS-7640/890FXA-GD70 (MS-7640)  , BIOS 
> >V1.8B1 09/13/2010
> >[   12.743223]  0000000000000009 ffffffff82203d88 ffffffff81afdba7 
> >ffffffff822184e0
> >[   12.743242]  0000000000000000 ffffffff82203dc8 ffffffff810bfdb2 
> >ffffffff81007858
> >[   12.743261]  0000000000000000 0000000000000001 0000000000000000 
> >ffff88005f60b120
> >[   12.743280] Call Trace:
> >[   12.743290]  [<ffffffff81afdba7>] dump_stack+0x46/0x58
> >[   12.743302]  [<ffffffff810bfdb2>] warn_slowpath_common+0x82/0xb0
> >[   12.743316]  [<ffffffff81007858>] ? pte_pfn_to_mfn+0x88/0xa0
> >[   12.743328]  [<ffffffff810bfdf5>] warn_slowpath_null+0x15/0x20
> >[   12.743341]  [<ffffffff81004b6b>] xen_mc_flush+0x1ab/0x1c0
> >[   12.743353]  [<ffffffff810072fd>] xen_alloc_pte+0x1ad/0x220
> >[   12.743364]  [<ffffffff8100886b>] ? xen_make_pte+0x1b/0x70
> >[   12.743378]  [<ffffffff81014a6f>] init_espfix_ap+0x22f/0x3f0
> >[   12.743392]  [<ffffffff8232079d>] init_espfix_bsp+0xee/0xf3
> >[   12.743404]  [<ffffffff82317ffe>] start_kernel+0x3d6/0x441
> >[   12.743416]  [<ffffffff82317a27>] ? set_init_arg+0x58/0x58
> >[   12.743428]  [<ffffffff82317608>] x86_64_start_reservations+0x2a/0x2c
> >[   12.743441]  [<ffffffff8231af8e>] xen_start_kernel+0x59b/0x59d
> >[   12.743468] ---[ end trace 20d3292a87f35842 ]---
> >[   12.743943] Dentry cache hash table entries: 262144 (order: 9, 2097152 
> >bytes)
> >[   12.744726] Inode-cache hash table entries: 131072 (order: 8, 1048576 
> >bytes)
> >[   12.745043] Mount-cache hash table entries: 4096 (order: 3, 32768 bytes)
> >[   12.745064] Mountpoint-cache hash table entries: 4096 (order: 3, 32768 
> >bytes)
> >[   12.745709] Initializing cgroup subsys freezer
> >[   12.745733] Initializing cgroup subsys blkio
> >
> >If you need more info / complete logs, give me a call.
> 
> This is caused by hpa's ESP fix for 16-bit programs leaking SP bits from
> 64-bit kernels (commit 3891a04aafd668686239349ea58f3314ea2af86b).
> 
> It's harmless in the sense that the only effect is that the workaround won't
> get enabled.

But oddly enough it only shows up on certain machines. I am wondering
if the issue is some E820 is not rounded up to a page size and we allocate
for the ESPFIX an not-4KB (ie, we cross-over) page. Hopefully the E820
will shed the light.

> 
> -boris
> 
> 
> 

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