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

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Friday, June 27, 2014, 4:15:30 PM, you wrote:

> 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.

I think it could be related to this in xl dmesg (sorry .. somehow didn't notice 
it before):

(XEN) [2014-06-29 09:43:48.956] mm.c:1215:d0v0 Global bit is set to kernel page 
7fe8d2ffb9
(XEN) [2014-06-29 09:43:48.956] mm.c:766:d0v0 Bad L1 flags 400000
(XEN) [2014-06-29 09:43:48.956] mm.c:1222:d0v0 Failure in alloc_l1_table: entry 
3
(XEN) [2014-06-29 09:43:48.956] mm.c:2100:d0v0 Error while validating mfn 
5469ad (pfn 59850) for type 1000000000000000: caf=8000000000000003 
taf=1000000000000001
(XEN) [2014-06-29 09:43:48.956] mm.c:2996:d0v0 Error while pinning mfn 5469ad


>> 
>> -boris
>> 
>> 
>> 



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