[Xen-devel] Random Dom0 Warning when starting PV guest

[Hongming Xiao <xiaohm@xxxxxxxxx>]

Hello,

I'm getting some random kernel warnings on dom0 boot that I'm concerned about.  Here is some information for my host and guest machines. I got both xen and kernel from CentOS 6.8 xen4centos.

Dom0:

  - xen-4.6.1-11.el6.x86_64

  - kernel-3.18.34-20.el6.x86_64

PV Guest:

  - kernel-3.18.34-20.el6.x86_64

dmesg output:

------------[ cut here ]------------
WARNING: CPU: 9 PID: 7412 at arch/x86/xen/multicalls.c:129 xen_mc_flush+0x162/0x1c0()
Modules linked in: ipmi_watchdog dcdbas mpt3sas mpt2sas scsi_transport_sas raid_class mptctl mptbase ipmi_si dell_rbu xen_pciback xen_gntalloc drbd lru_cache libcrc32c ebt_ip ebtable_filter ebtables bridge stp llc ipt_REJECT nf_reject_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack iptable_filter ip_tables xt_limit ip6t_REJECT nf_reject_ipv6 ip6table_filter ip6_tables ipv6 ebt_limit blktap xen_netback xen_blkback xen_gntdev xen_evtchn xenfs xen_privcmd pcspkr sb_edac edac_core joydev shpchp sg tg3 ptp pps_core 8250_fintek ipmi_devintf ipmi_msghandler lpc_ich mei_me mei acpi_power_meter hwmon ext3 jbd mbcache sr_mod cdrom sd_mod ahci libahci megaraid_sas wmi mgag200 ttm drm_kms_helper dm_mirror dm_region_hash dm_log dm_mod [last unloaded: ipmi_si]
CPU: 9 PID: 7412 Comm: qldup_inv Not tainted 3.18.34-20.el6.x86_64 #1
Hardware name:    /086D43, BIOS 1.5.4 10/002/2015
 0000000000000000 ffff880028b9ba98 ffffffff81675c27 0000000000000000
 0000000000000081 ffff880028b9bad8 ffffffff81073c5c 0000000000000000
 ffff88003372a100 0000000000000000 0000000000000001 0000000000000001
Call Trace:
 [<ffffffff81675c27>] dump_stack+0x64/0x85
 [<ffffffff81073c5c>] warn_slowpath_common+0x8c/0xc0
 [<ffffffff81073caa>] warn_slowpath_null+0x1a/0x20
 [<ffffffff81005412>] xen_mc_flush+0x162/0x1c0
 [<ffffffff81005590>] __xen_mc_entry+0x120/0x190
 [<ffffffff810069ea>] xen_extend_mmu_update+0x7a/0x110
 [<ffffffff8100b4af>] xen_set_pte_at+0x15f/0x2c0
 [<ffffffff81193eec>] remap_pfn_range+0x36c/0x460
 [<ffffffff811e0b80>] ? cdev_put+0x30/0x30
 [<ffffffff813fcc23>] mmap_mem+0x103/0x110
 [<ffffffff8119c7f0>] mmap_region+0x3f0/0x630
 [<ffffffff8119ccfc>] do_mmap_pgoff+0x2cc/0x430
 [<ffffffff81181a0d>] vm_mmap_pgoff+0xad/0xe0
 [<ffffffff811bcd20>] ? kmem_cache_free+0xf0/0x280
 [<ffffffff8119a02e>] SyS_mmap_pgoff+0xee/0x200
 [<ffffffff8167ca1a>] sysenter_dispatch+0x7/0x21
---[ end trace 66b9f7abd0aed691 ]---
------------[ cut here ]------------
WARNING: CPU: 9 PID: 7412 at arch/x86/xen/multicalls.c:129 xen_mc_flush+0x162/0x1c0()
Modules linked in: ipmi_watchdog dcdbas mpt3sas mpt2sas scsi_transport_sas raid_class mptctl mptbase ipmi_si dell_rbu xen_pciback xen_gntalloc drbd lru_cache libcrc32c ebt_ip ebtable_filter ebtables bridge stp llc ipt_REJECT nf_reject_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack iptable_filter ip_tables xt_limit ip6t_REJECT nf_reject_ipv6 ip6table_filter ip6_tables ipv6 ebt_limit blktap xen_netback xen_blkback xen_gntdev xen_evtchn xenfs xen_privcmd pcspkr sb_edac edac_core joydev shpchp sg tg3 ptp pps_core 8250_fintek ipmi_devintf ipmi_msghandler lpc_ich mei_me mei acpi_power_meter hwmon ext3 jbd mbcache sr_mod cdrom sd_mod ahci libahci megaraid_sas wmi mgag200 ttm drm_kms_helper dm_mirror dm_region_hash dm_log dm_mod [last unloaded: ipmi_si]
CPU: 9 PID: 7412 Comm: qldup_inv Tainted: G        W      3.18.34-20.el6.x86_64 #1
Hardware name:    /086D43, BIOS 1.5.4 10/002/2015
 0000000000000000 ffff880028b9ba98 ffffffff81675c27 0000000000000000
 0000000000000081 ffff880028b9bad8 ffffffff81073c5c 0000000000000000
 ffff88003372a100 0000000000000000 0000000000000001 0000000000000001
Call Trace:
 [<ffffffff81675c27>] dump_stack+0x64/0x85
 [<ffffffff81073c5c>] warn_slowpath_common+0x8c/0xc0
 [<ffffffff81073caa>] warn_slowpath_null+0x1a/0x20
 [<ffffffff81005412>] xen_mc_flush+0x162/0x1c0
 [<ffffffff81005590>] __xen_mc_entry+0x120/0x190
 [<ffffffff810069ea>] xen_extend_mmu_update+0x7a/0x110
 [<ffffffff8100b4af>] xen_set_pte_at+0x15f/0x2c0
 [<ffffffff81193eec>] remap_pfn_range+0x36c/0x460
 [<ffffffff811e0b80>] ? cdev_put+0x30/0x30
 [<ffffffff813fcc23>] mmap_mem+0x103/0x110
 [<ffffffff8119c7f0>] mmap_region+0x3f0/0x630
 [<ffffffff8119ccfc>] do_mmap_pgoff+0x2cc/0x430
 [<ffffffff81181a0d>] vm_mmap_pgoff+0xad/0xe0
 [<ffffffff811bcd20>] ? kmem_cache_free+0xf0/0x280
 [<ffffffff8119a02e>] SyS_mmap_pgoff+0xee/0x200
 [<ffffffff8167ca1a>] sysenter_dispatch+0x7/0x21
---[ end trace 66b9f7abd0aed692 ]---

Any idea on what is going on and does this warning has any indication on any potential problem of the system?  I found a similar problem reported at https://lists.gt.net/xen/users/215518 but in that case the problem is reported in the guest instead of dom0. And, the solution mentioned there doesn't make any sense to me.  

Thanks in advance for looking into the problem.

Mike

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