[Samba] CTDB/Kernel BUG

[Alex Crow]

Hi List,

We're currently seeing a kernel BUG in conjunction with CTDB.

This is on hosts running latest Centos 7.2 with Samba/CTDB from standard 
repos. Underlying FS is MooseFS backed by ZFS. Every so often, 
especially when CIFS activity is high (eg 100+ users loading or saving 
Windows profiles, we see a BUG in our logs:

Jun 20 16:31:13 metamora kernel: BUG: Bad page state in process 
ctdb_recovered  pfn:8c8e00
Jun 20 16:31:13 metamora kernel: page:ffffea0023238000 count:0 
mapcount:0 mapping:          (null) index:0x7ff509800
Jun 20 16:31:13 metamora kernel: page flags: 
0x2fffff00184008(uptodate|head|swapbacked|unevictable)
Jun 20 16:31:13 metamora kernel: page dumped because: 
PAGE_FLAGS_CHECK_AT_FREE flag(s) set
Jun 20 16:31:13 metamora kernel: bad because of flags:
Jun 20 16:31:13 metamora kernel: page flags: 0x100000(unevictable)
Jun 20 16:31:13 metamora kernel: Modules linked in: iptable_filter 
binfmt_misc fuse bonding iTCO_wdt iTCO_vendor_support mxm_wmi 
intel_powerclamp coretemp intel_rapl kvm_intel kvm crc32_pclmul 
ghash_clmulni_intel aesni_intel lrw gf128mul glue_helper ablk_helper 
cryptd pcspkr sb_edac edac_core i2c_i801 lpc_ich mfd_core mei_me mei ses 
enclosure sg ioatdma shpchp ipmi_ssif ipmi_si ipmi_msghandler wmi 
acpi_pad acpi_power_meter ip_tables xfs libcrc32c raid1 sd_mod 
crc_t10dif crct10dif_generic ast syscopyarea crct10dif_pclmul 
sysfillrect crct10dif_common sysimgblt crc32c_intel drm_kms_helper ttm 
drm ixgbe ahci igb libahci mpt3sas mdio libata ptp i2c_algo_bit 
raid_class pps_core i2c_core scsi_transport_sas dca dm_mirror 
dm_region_hash dm_log dm_mod zfs(POE) zunicode(POE) zavl(POE) 
zcommon(POE) znvpair(POE) spl(OE) zlib_deflate
Jun 20 16:31:13 metamora kernel:
Jun 20 16:31:13 metamora kernel: CPU: 23 PID: 13830 Comm: ctdb_recovered 
Tainted: P    B      OE  ------------ 3.10.0-327.13.1.el7.x86_64 #1
Jun 20 16:31:13 metamora kernel: Hardware name: Supermicro 
X10DRi/X10DRi, BIOS 2.0 12/28/2015
Jun 20 16:31:13 metamora kernel: ffffea0023238000 00000000888bd1fd 
ffff883d6a677c50 ffffffff8163571c
Jun 20 16:31:13 metamora kernel: ffff883d6a677c78 ffffffff81630935 
ffffea0023238000 0000000000000000
Jun 20 16:31:13 metamora kernel: 000fffff00000000 ffff883d6a677cc0 
ffffffff811711ad fff00000fe000000
Jun 20 16:31:13 metamora kernel: Call Trace:
Jun 20 16:31:13 metamora kernel: [<ffffffff8163571c>] dump_stack+0x19/0x1b
Jun 20 16:31:13 metamora kernel: [<ffffffff81630935>] 
bad_page.part.59+0xdf/0xfc
Jun 20 16:31:13 metamora kernel: [<ffffffff811711ad>] 
free_pages_prepare+0x16d/0x190
Jun 20 16:31:13 metamora kernel: [<ffffffff81171589>] 
free_compound_page+0x29/0x40
Jun 20 16:31:13 metamora kernel: [<ffffffff81176ddf>] 
__put_compound_page+0x1f/0x30
Jun 20 16:31:13 metamora kernel: [<ffffffff81176e51>] 
put_compound_page+0x31/0x170
Jun 20 16:31:13 metamora kernel: [<ffffffff81176fbc>] put_page+0x2c/0x40
Jun 20 16:31:13 metamora kernel: [<ffffffff811c8737>] 
migrate_misplaced_transhuge_page+0x5a7/0x6c0
Jun 20 16:31:13 metamora kernel: [<ffffffff811cadc2>] 
do_huge_pmd_numa_page+0x1d2/0x340
Jun 20 16:31:13 metamora kernel: [<ffffffff811971b4>] 
handle_mm_fault+0x5e4/0xf50
Jun 20 16:31:13 metamora kernel: [<ffffffff81230b84>] ? 
locks_free_lock+0x64/0x70
Jun 20 16:31:13 metamora kernel: [<ffffffff81233636>] ? 
fcntl_setlk+0x66/0x310
Jun 20 16:31:13 metamora kernel: [<ffffffff816413c0>] 
__do_page_fault+0x150/0x450
Jun 20 16:31:13 metamora kernel: [<ffffffff816416e3>] 
do_page_fault+0x23/0x80
Jun 20 16:31:13 metamora kernel: [<ffffffff8163d948>] page_fault+0x28/0x30

I am not sure if this is a real problem or is simply cosmetic.

Any help or suggestions would be much appreciated.

Software versions:

Linux metamora.ifa.net 3.10.0-327.18.2.el7.x86_64 #1 SMP Thu May 12 
11:03:55 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Installed Packages
Name        : ctdb
Arch        : x86_64
Version     : 4.2.10
Release     : 6.el7_2
Size        : 1.2 M

Installed Packages
Name        : samba
Arch        : x86_64
Version     : 4.2.10
Release     : 6.el7_2
Size        : 1.8 M

Installed Packages
Name        : zfs
Arch        : x86_64
Version     : 0.6.5.7
Release     : 1.el7.centos
Size        : 800 k

Installed Packages
Name        : moosefs-pro-client
Arch        : x86_64
Version     : 3.0.78
Release     : 1.rhsystemd
Size        : 595 k

Thanks,

Alex
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