Bug 76421

Summary: Hang on deletion
Product: File System Reporter: Joshua McKinney (bugzilla)
Component: btrfsAssignee: Josef Bacik (josef)
Status: RESOLVED CODE_FIX    
Severity: normal CC: alan, boatingbum23, cedricde, dsterba, evetsso, joe, lukas.karas, m+kernel-bugs, martin, net147, ray.maslinski, stijn+bugs, szg00000, thonaldo
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 3.14.4-1-ARCH Subsystem:
Regression: No Bisected commit-id:

Description Joshua McKinney 2014-05-18 16:23:54 UTC 
Perceived issue: SABNZBD hangs, requires restart.
Diagnosis shows the following in my system log at the time of hang.
Happens more than once.

Log:

[ 5883.464766] INFO: task SABnzbd.py:994 blocked for more than 120 seconds.
[ 5883.464906]       Not tainted 3.14.4-1-ARCH #1
[ 5883.464989] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 5883.465130] SABnzbd.py      D ffff880196d1f5c0     0   994      1 0x00000000
[ 5883.465140]  ffff8800765c9ce8 0000000000000082 0000005000000002 ffff880196d1f5c0
[ 5883.465148]  00000000000146c0 ffff8800765c9fd8 00000000000146c0 ffff880196d1f5c0
[ 5883.465156]  00000000ffffffef ffff880177d9a000 ffffffffa02d0dbc ffff8800765c9c50
[ 5883.465163] Call Trace:
[ 5883.465218]  [<ffffffffa02d0dbc>] ? __set_extent_bit+0x45c/0x550 [btrfs]
[ 5883.465252]  [<ffffffffa02d03c3>] ? free_extent_state+0x43/0xc0 [btrfs]
[ 5883.465284]  [<ffffffffa02d0dbc>] ? __set_extent_bit+0x45c/0x550 [btrfs]
[ 5883.465295]  [<ffffffff810b3ba4>] ? __wake_up+0x44/0x50
[ 5883.465304]  [<ffffffff8150b729>] schedule+0x29/0x70
[ 5883.465335]  [<ffffffffa02d1cd2>] lock_extent_bits+0x152/0x1e0 [btrfs]
[ 5883.465344]  [<ffffffff810b4020>] ? __wake_up_sync+0x20/0x20
[ 5883.465375]  [<ffffffffa02bfa59>] btrfs_evict_inode+0x139/0x520 [btrfs]
[ 5883.465387]  [<ffffffff811d5a80>] evict+0xb0/0x1c0
[ 5883.465394]  [<ffffffff811d6335>] iput+0xf5/0x1a0
[ 5883.465402]  [<ffffffff811ca9c5>] do_unlinkat+0x1b5/0x300
[ 5883.465411]  [<ffffffff8117899c>] ? vm_munmap+0x4c/0x60
[ 5883.465418]  [<ffffffff811cb986>] SyS_unlink+0x16/0x20
[ 5883.465427]  [<ffffffff81517769>] system_call_fastpath+0x16/0x1b

Filesystem:
# btrfs filesystem show
Btrfs v3.14.1

running Data RAID, sys/meta RAID10 on 5x4TB. SABNzbd is a usenet download program, so the file attempting to be deleted was possibly large (>GB)

Recently updated to 3.14 kernel provided in arch linux. I haven't seen this issue before the last couple of days.

Happy to provide more info if necessary.
Comment 1 Chris 2014-05-21 01:21:13 UTC 
I have been having a similar problem for the last week. 

I can create files until the disks are filled and they are fine and mounted R/W until I delete the files, at which point they get mounted Read Only. 

I am running a Raid 10 with a pair of 1TB and 3TB disks. 

Attached is my dmesg log. 

[ 1022.660808] WARNING: CPU: 1 PID: 2225 at fs/btrfs/super.c:257 __btrfs_abort_transaction+0x50/0x110 [btrfs]()
[ 1022.660814] Modules linked in: fuse btrfs kvm_amd kvm crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel radeon mousedev raid6_pq aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper cryptd microcode psmouse pcspkr serio_raw k10temp xor snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec_hdmi i2c_piix4 snd_hda_intel r8169 ttm mii snd_hda_codec drm_kms_helper tpm_tis snd_hwdep tpm snd_pcm drm snd_timer snd hwmon soundcore i2c_algo_bit i2c_core shpchp acpi_cpufreq processor fglrx(PO) evdev mac_hid amd_iommu_v2 button ext4 crc16 mbcache jbd2 sd_mod crc_t10dif crct10dif_common hid_generic usbhid hid atkbd libps2 sata_via ehci_pci ohci_pci ohci_hcd xhci_hcd ehci_hcd usbcore usb_common i8042 serio ahci libahci libata scsi_mod
[ 1022.660902] CPU: 1 PID: 2225 Comm: btrfs Tainted: P        W  O 3.14.4-1-ARCH #1
[ 1022.660968]  [<ffffffffa0fe2040>] __btrfs_abort_transaction+0x50/0x110 [btrfs]
[ 1022.660985]  [<ffffffffa0ff4aa6>] __btrfs_free_extent+0x136/0xa90 [btrfs]
[ 1022.661006]  [<ffffffffa1058d79>] ? btrfs_merge_delayed_refs+0x449/0x470 [btrfs]
[ 1022.661024]  [<ffffffffa1057b62>] ? find_ref_head.constprop.4+0x62/0x90 [btrfs]
[ 1022.661040]  [<ffffffffa0ffa046>] __btrfs_run_delayed_refs+0x916/0x1270 [btrfs]
[ 1022.661062]  [<ffffffffa102aefb>] ? release_extent_buffer+0x2b/0xd0 [btrfs]
[ 1022.661080]  [<ffffffffa0ffe8eb>] btrfs_run_delayed_refs.part.52+0x7b/0x260 [btrfs]
[ 1022.661097]  [<ffffffffa0ffeae7>] btrfs_run_delayed_refs+0x17/0x20 [btrfs]
[ 1022.661116]  [<ffffffffa10101a3>] __btrfs_end_transaction+0x243/0x380 [btrfs]
[ 1022.661135]  [<ffffffffa1010374>] btrfs_defrag_root+0x74/0xe0 [btrfs]
[ 1022.661155]  [<ffffffffa104457f>] btrfs_ioctl_defrag+0x13f/0x180 [btrfs]
[ 1022.661174]  [<ffffffffa1046617>] btrfs_ioctl+0x1a27/0x2a80 [btrfs]
[ 1022.661246] BTRFS: error (device sda) in __btrfs_free_extent:5756: errno=-5 IO failure
[ 1022.661256] BTRFS: error (device sda) in btrfs_run_delayed_refs:2714: errno=-5 IO failure
Comment 2 Thomas 2014-06-20 15:17:18 UTC 
I am also affected by the original issue.

Again, it is triggered when SABnzbd deletes, but my setup is much simpler: A single 250GB SSD with btrfs, no RAID. The machine is running ArchLinux and the problem started with 3.14 (IIRC) and still occurs in 3.15.1.

To be more precise: There is a folder with ~140 files inside (each ~50 MB in size). Upon deleting this folder (or the files therein), the error message below appears. The folder still exists, but it is empty (as it should be) and the program hangs until I restart the machine.

The log looks as follows:

[17874.289727] INFO: task SABnzbd.py:682 blocked for more than 120 seconds.
[17874.289731]       Tainted: G           O  3.15.1-1-ARCH #1
[17874.289731] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[17874.289733] SABnzbd.py      D 0000000000000001     0   682      1 0x00000000
[17874.289735]  ffff88020faa7ce0 0000000000000082 ffff88020f91d180 0000000000014700
[17874.289737]  ffff88020faa7fd8 0000000000014700 ffff88020f91d180 00000000ffffffef
[17874.289739]  ffff88008b2f2de0 ffffffffa08316bc ffff88020faa7c48 ffffffffa0830c73
[17874.289740] Call Trace:
[17874.289759]  [<ffffffffa08316bc>] ? __set_extent_bit+0x45c/0x550 [btrfs]
[17874.289766]  [<ffffffffa0830c73>] ? free_extent_state+0x43/0xc0 [btrfs]
[17874.289771]  [<ffffffffa08316bc>] ? __set_extent_bit+0x45c/0x550 [btrfs]
[17874.289775]  [<ffffffff81509a19>] schedule+0x29/0x70
[17874.289781]  [<ffffffffa083261d>] lock_extent_bits+0x19d/0x200 [btrfs]
[17874.289783]  [<ffffffff810b1bd0>] ? __wake_up_sync+0x20/0x20
[17874.289791]  [<ffffffffa08200f9>] btrfs_evict_inode+0x139/0x520 [btrfs]
[17874.289794]  [<ffffffff811cf754>] evict+0xb4/0x1a0
[17874.289796]  [<ffffffff811cffe5>] iput+0xf5/0x1a0
[17874.289798]  [<ffffffff811c4165>] do_unlinkat+0x1b5/0x300
[17874.289801]  [<ffffffff81174d2c>] ? vm_munmap+0x4c/0x60
[17874.289803]  [<ffffffff811c5226>] SyS_unlink+0x16/0x20
[17874.289805]  [<ffffffff815159a9>] system_call_fastpath+0x16/0x1b
Comment 3 Joe Peterson 2014-07-10 03:48:33 UTC 
I just got the same problem while trying to "rm -rf" a large directory tree. I am running kernel 3.15.3-1-ARCH. Here's the trace:

Jul  9 20:07:42 nova kernel: sed             D 0000000000000002     0 23893     
 1 0x00000004
Jul  9 20:07:42 nova kernel:  ffff8800036a3ba0 0000000000000086 ffff880110df32f0
 0000000000014700
Jul  9 20:07:42 nova kernel:  ffff8800036a3fd8 0000000000014700 ffff880110df32f0
 00000000ffffffef
Jul  9 20:07:42 nova kernel:  ffff88006bc76c00 ffffffffa02666fc ffff8800036a3b08
 ffffffffa0265cb3
Jul  9 20:07:42 nova kernel: Call Trace:
Jul  9 20:07:42 nova kernel:  [<ffffffffa02666fc>] ? __set_extent_bit+0x45c/0x55
0 [btrfs]
Jul  9 20:07:42 nova kernel:  [<ffffffffa0265cb3>] ? free_extent_state+0x43/0xc0
 [btrfs]
Jul  9 20:07:42 nova kernel:  [<ffffffffa02666fc>] ? __set_extent_bit+0x45c/0x55
0 [btrfs]
Jul  9 20:07:42 nova kernel:  [<ffffffff81509ef9>] schedule+0x29/0x70
Jul  9 20:07:42 nova kernel:  [<ffffffffa026765d>] lock_extent_bits+0x19d/0x200 
[btrfs]
Jul  9 20:07:42 nova kernel:  [<ffffffff810b1c10>] ? __wake_up_sync+0x20/0x20
Jul  9 20:07:42 nova kernel:  [<ffffffffa0255149>] btrfs_evict_inode+0x139/0x520
 [btrfs]
Jul  9 20:07:42 nova kernel:  [<ffffffff811cf974>] evict+0xb4/0x1a0
Jul  9 20:07:42 nova kernel:  [<ffffffff811d0205>] iput+0xf5/0x1a0
Jul  9 20:07:42 nova kernel:  [<ffffffff811cb8b8>] __dentry_kill+0x1a8/0x200
Jul  9 20:07:42 nova kernel:  [<ffffffff811cb9d8>] dput+0xc8/0x1c0
Jul  9 20:07:42 nova kernel:  [<ffffffff811c5c09>] SyS_renameat2+0x389/0x540
Jul  9 20:07:42 nova kernel:  [<ffffffff81199769>] ? kmem_cache_free+0x199/0x1d0
Jul  9 20:07:42 nova kernel:  [<ffffffff81174edc>] ? vm_munmap+0x4c/0x60
Jul  9 20:07:42 nova kernel:  [<ffffffff811c5dfe>] SyS_rename+0x1e/0x20
Jul  9 20:07:42 nova kernel:  [<ffffffff81515ee9>] system_call_fastpath+0x16/0x1
b

Hope this is of help. Please advise if I can provide further info.
Comment 4 Joe Peterson 2015-01-27 21:20:05 UTC 
I just got this again, doing a similar operation (a build of Chromium from source). Again, I could not remove the "src" dir (hung while attempting). I am now at kernel 3.18.2-2-ARCH. So the problem persists.

I am also using a very simple filesystem (plain btrfs on SSD drive, no RAID).

Anything we can do to help debug?



Jan 27 13:32:36 nova kernel: sed             D 0000000000000000     0  6344      1 0x00000004
Jan 27 13:32:36 nova kernel:  ffff88017ab83b68 0000000000000086 ffff88022f21c670 0000000000013640
Jan 27 13:32:36 nova kernel:  ffff88017ab83fd8 0000000000013640 ffff880076ca3250 ffff88022f21c670
Jan 27 13:32:36 nova kernel:  ffff88017ab83ab8 ffffffffa02143ca 0000000000000fff 00000000ffffffef
Jan 27 13:32:36 nova kernel: Call Trace:
Jan 27 13:32:36 nova kernel:  [<ffffffffa02143ca>] ? free_extent_state+0x4a/0xd0 [btrfs]
Jan 27 13:32:36 nova kernel:  [<ffffffffa0214e0f>] ? __set_extent_bit+0x46f/0x560 [btrfs]
Jan 27 13:32:36 nova kernel:  [<ffffffff81550b59>] schedule+0x29/0x70
Jan 27 13:32:36 nova kernel:  [<ffffffffa0215cbb>] lock_extent_bits+0x1ab/0x220 [btrfs]
Jan 27 13:32:36 nova kernel:  [<ffffffff810b2e30>] ? __wake_up_sync+0x20/0x20
Jan 27 13:32:36 nova kernel:  [<ffffffffa0203152>] btrfs_evict_inode+0x162/0x550 [btrfs]
Jan 27 13:32:36 nova kernel:  [<ffffffff811eab68>] evict+0xb8/0x1b0
Jan 27 13:32:36 nova kernel:  [<ffffffff811eb405>] iput+0xf5/0x1a0
Jan 27 13:32:36 nova kernel:  [<ffffffff811e69f8>] __dentry_kill+0x188/0x200
Jan 27 13:32:36 nova kernel:  [<ffffffff811e6b38>] dput+0xc8/0x1c0
Jan 27 13:32:36 nova kernel:  [<ffffffff811e0b29>] SyS_renameat2+0x429/0x5f0
Jan 27 13:32:36 nova kernel:  [<ffffffff8118c117>] ? vma_rb_erase+0x147/0x260
Jan 27 13:32:36 nova kernel:  [<ffffffff811e0d2e>] SyS_rename+0x1e/0x20
Jan 27 13:32:36 nova kernel:  [<ffffffff81554ca9>] system_call_fastpath+0x12/0x17
Comment 5 Stijn Tintel 2015-03-17 10:03:32 UTC 
Ran into this on a BTRFS RAID6 on 6x2TB LUKS encrypted drives. Kernel 3.19.0. The filesystem was created on a 3.19.0-rc6 kernel, with btrfs-progs-3.18.2, -O skinny-metadata,no-holes.

[261745.159447] INFO: task python2.7:4956 blocked for more than 120 seconds.
[261745.159452]       Not tainted 3.19.0-gentoo #1
[261745.159453] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[261745.159455] python2.7       D ffff8800df48bcc8     0  4956      1 0x00000000
[261745.159460]  ffff8800df48bcc8 ffff8800df48bcb8 0000000000009000 ffff88020b5a3120
[261745.159464]  ffff8800df48bfd8 ffff88014ca14088 0000000000029fff ffff8800120a0c60
[261745.159467]  ffff88014ca14088 ffff8800df48bc28 ffffffffa024bf45 ffff8800df48bc38
[261745.159470] Call Trace:
[261745.159510]  [<ffffffffa024bf45>] ? free_extent_state.part.34+0x25/0x40 [btrfs]
[261745.159528]  [<ffffffffa024c3d9>] ? free_extent_state+0x19/0x20 [btrfs]
[261745.159545]  [<ffffffffa024cc8e>] ? __set_extent_bit+0x3ae/0x510 [btrfs]
[261745.159550]  [<ffffffff814adcf4>] schedule+0x24/0x70
[261745.159566]  [<ffffffffa024da8a>] lock_extent_bits+0x18a/0x1e0 [btrfs]
[261745.159571]  [<ffffffff8107ed20>] ? wait_woken+0x80/0x80
[261745.159589]  [<ffffffffa023c90f>] btrfs_evict_inode+0x11f/0x4c0 [btrfs]
[261745.159598]  [<ffffffff8116458e>] evict+0xae/0x170
[261745.159602]  [<ffffffff81164d7b>] iput+0xeb/0x180
[261745.159605]  [<ffffffff8115a97b>] do_unlinkat+0x1bb/0x2e0
[261745.159608]  [<ffffffff8115b231>] SyS_unlink+0x11/0x20
[261745.159612]  [<ffffffff814b11d6>] system_call_fastpath+0x16/0x1b
Comment 6 martin 2015-03-21 16:00:25 UTC 
Hit this (or something similar) on Gentoo, 3.19.1, 2 separate machines. 100% triggerable when running emerge gentoo-sources. (installing the kernel source package). No RAID. 

[ 2162.243789] INFO: task emerge:19900 blocked for more than 120 seconds.
[ 2162.243799]       Not tainted 3.19.1-gentoo-ARCH #2
[ 2162.243802] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2162.243806] emerge          D ffff8800153e7cb8     0 19900   1403 0x00000000
[ 2162.243814]  ffff8800153e7cb8 ffff88000c1862c0 0000000000013e80 ffff8800153e7fd8
[ 2162.243820]  0000000000013e80 ffff88000c1809e0 ffff88000c1862c0 ffff8800206731b8
[ 2162.243826]  ffffffff8129949c ffff8800153e7c18 ffffffff81298a9a 000000000000ffff
[ 2162.243832] Call Trace:
[ 2162.243848]  [<ffffffff8129949c>] ? __set_extent_bit+0x44c/0x540
[ 2162.243855]  [<ffffffff81298a9a>] ? free_extent_state+0x4a/0xd0
[ 2162.243862]  [<ffffffff8129949c>] ? __set_extent_bit+0x44c/0x540
[ 2162.243870]  [<ffffffff8160fac9>] schedule+0x29/0x70
[ 2162.243877]  [<ffffffff8129a2dd>] lock_extent_bits+0x18d/0x1e0
[ 2162.243885]  [<ffffffff810aef60>] ? wait_woken+0x90/0x90
[ 2162.243891]  [<ffffffff81288052>] btrfs_evict_inode+0x152/0x520
[ 2162.243898]  [<ffffffff811ddfc8>] evict+0xb8/0x1b0
[ 2162.243903]  [<ffffffff811de855>] iput+0xf5/0x1a0
[ 2162.243910]  [<ffffffff811d346a>] do_unlinkat+0x1ba/0x330
[ 2162.243917]  [<ffffffff811e2a84>] ? mntput+0x24/0x40
[ 2162.243922]  [<ffffffff811ccb82>] ? path_put+0x22/0x30
[ 2162.243927]  [<ffffffff811c2033>] ? SyS_fchmodat+0x53/0xb0
[ 2162.243933]  [<ffffffff811d3eb6>] SyS_unlink+0x16/0x20
[ 2162.243939]  [<ffffffff81613729>] system_call_fastpath+0x12/0x17
Comment 7 Lukáš Karas 2015-04-08 13:36:54 UTC 
Kernel 4.0.0-rc6 is still affected by this bug. It occurs once per week on my machine. I use SSD (C400-MTFDDAK256M) disk formated with btrfs for root fs and home directory (with ecryptfs)...

[118637.160102] INFO: task java:1655 blocked for more than 120 seconds.
[118637.160105]       Tainted: G        W       4.0.0-rc6 #1
[118637.160106] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[118637.160107] java            D ffff880118837c28     0  1655   6245 0x00000004
[118637.160110]  ffff880118837c28 ffff8802146149b0 ffff8801bd05e240 0000001018837c98
[118637.160112]  ffff880118837fd8 00000000ffffffef ffff880118837fd8 ffff88001022262c
[118637.160114]  ffff880010222610 0000000000001000 ffff8801bcb36290 ffff880118837c48
[118637.160115] Call Trace:
[118637.160121]  [<ffffffff81712e87>] schedule+0x37/0x90
[118637.160124]  [<ffffffff813051e2>] lock_extent_bits+0x202/0x240
[118637.160127]  [<ffffffff8109ae10>] ? wait_woken+0x90/0x90
[118637.160129]  [<ffffffff812f2b4f>] btrfs_evict_inode+0x14f/0x500
[118637.160131]  [<ffffffff811b87c3>] evict+0xb3/0x1a0
[118637.160133]  [<ffffffff811b914d>] iput+0x18d/0x200
[118637.160150]  [<ffffffffa03710f1>] ecryptfs_evict_inode+0x31/0x40 [ecryptfs]
[118637.160151]  [<ffffffff811b87c3>] evict+0xb3/0x1a0
[118637.160152]  [<ffffffff811b914d>] iput+0x18d/0x200
[118637.160154]  [<ffffffff811ad929>] do_unlinkat+0x159/0x370
[118637.160157]  [<ffffffff810117e5>] ? syscall_trace_enter_phase1+0x105/0x170
[118637.160160]  [<ffffffff81002d25>] ? do_notify_resume+0x95/0xa0
[118637.160161]  [<ffffffff811aed46>] SyS_unlink+0x16/0x20
[118637.160163]  [<ffffffff81716ff2>] system_call_fastpath+0x12/0x17
Comment 8 Steve Leung 2015-05-26 14:50:41 UTC 
Filipe just posted a patch that looks like it ought to solve this:

http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg43561.html
Comment 9 martin 2015-08-29 14:48:54 UTC 
Just happened with 4.1.4.
Again while installing a new version of kernel sources.

[165395.120530] INFO: task emerge:7472 blocked for more than 120 seconds.
[165395.120537]       Not tainted 4.1.4-gentoo-ARCH #1
[165395.120539] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[165395.120542] emerge          D ffff8800063cfc78     0  7472   6348 0x00000000
[165395.120549]  ffff8800063cfc78 ffff88003b783cc0 ffff880035988a20 00000000016a0085
[165395.120554]  ffff8800063d0000 ffff880007eb1b0c ffff880007eb1af0 0000000000001000
[165395.120558]  ffff8800395bba60 ffff8800063cfc98 ffffffff81632577 ffff880007eb1b0c
[165395.120563] Call Trace:
[165395.120573]  [<ffffffff81632577>] schedule+0x37/0x90
[165395.120578]  [<ffffffff812a5dbd>] lock_extent_bits+0x18d/0x1e0
[165395.120584]  [<ffffffff810b3e90>] ? wait_woken+0x90/0x90
[165395.120588]  [<ffffffff81293772>] btrfs_evict_inode+0x152/0x580
[165395.120593]  [<ffffffff811e5b78>] evict+0xb8/0x1b0
[165395.120596]  [<ffffffff811e64db>] iput+0x1bb/0x220
[165395.120600]  [<ffffffff811db023>] do_unlinkat+0x203/0x320
[165395.120605]  [<ffffffff811eaa94>] ? mntput+0x24/0x40
[165395.120610]  [<ffffffff811d4372>] ? path_put+0x22/0x30
[165395.120615]  [<ffffffff811c9893>] ? SyS_fchmodat+0x53/0xb0
[165395.120619]  [<ffffffff811db926>] SyS_unlink+0x16/0x20
[165395.120623]  [<ffffffff816371ae>] system_call_fastpath+0x12/0x71
Comment 10 Steve Leung 2015-09-04 05:42:11 UTC 
The patch I mentioned above was merged into 4.2-rc1, and so far on 4.2 (Arch Linux) I'm unable to reproduce this.

In earlier kernels I was able to reproduce this easily using sabnzbd, but so far so good.
Comment 11 martin 2015-09-05 14:59:58 UTC 
Hi, sorry, somehow I got the idea that it got merged as a bugfix...
Installed 4.2, emerged a couple of linux sources, no issues so far. 
Thanks.