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[Bug 1423672] Re: ext4_mb_generate_buddy:756: group N, block bitmap and bg descriptor inconsistent: X vs Y

To: kernel-packages@xxxxxxxxxxxxxxxxxxx
From: Simon Déziel <1423672@xxxxxxxxxxxxxxxxxx>
Date: Wed, 25 May 2016 17:43:38 -0000
Reply-to: Bug 1423672 <1423672@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx
Louie, https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818502#22
provides a simple way to reproduce. If you could give it a try that
would be appreciated.

FYI, when my hypervisor was running Trusty (3.13), the problem was
reproducible on fresh VMs with brand new ext4 FSes, so hopefully that
will be easy to reproduce for you.

-- 
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https://bugs.launchpad.net/bugs/1423672

Title:
  ext4_mb_generate_buddy:756: group N, block bitmap and bg descriptor
  inconsistent: X vs Y

Status in Linux:
  Unknown
Status in linux package in Ubuntu:
  Confirmed
Status in linux-lts-utopic package in Ubuntu:
  Invalid
Status in linux source package in Trusty:
  Fix Committed
Status in linux-lts-utopic source package in Trusty:
  Fix Committed
Status in linux package in Debian:
  Confirmed

Bug description:
   SRU Justification:

      Impact: Users of VMs running 3.13/3.16 and ext4 can experience data corruption in the guest.
      Fix: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?h=7dec5603b6b8dc4c3e1c65d318bd2a5a8c62a424
      Testcase: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=818502#22

  --

  I noticed that one of my VM had this "dmesg -T" output:

  [Tue Feb 17 09:53:27 2015] systemd-udevd[5433]: starting version 204
  [Thu Feb 19 06:25:08 2015] EXT4-fs error (device vda1): ext4_mb_generate_buddy:756: group 5, block bitmap and bg descriptor inconsistent: 16446 vs 16445 free clusters
  [Thu Feb 19 06:25:09 2015] Aborting journal on device vda1-8.
  [Thu Feb 19 06:25:09 2015] EXT4-fs (vda1): Remounting filesystem read-only
  [Thu Feb 19 06:25:09 2015] ------------[ cut here ]------------
  [Thu Feb 19 06:25:09 2015] WARNING: CPU: 0 PID: 9946 at /build/buildd/linux-3.13.0/fs/ext4/ext4_jbd2.c:259 __ext4_handle_dirty_metadata+0x1a2/0x1c0()
  [Thu Feb 19 06:25:09 2015] Modules linked in: nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_tcpudp nf_conntrack_ipv4 nf_defrag_ipv4 xt_owner xt_conntrack nf_conntrack iptable_filter ip_tables x_tables serio_raw psmouse floppy
  [Thu Feb 19 06:25:09 2015] CPU: 0 PID: 9946 Comm: logrotate Not tainted 3.13.0-45-generic #74-Ubuntu
  [Thu Feb 19 06:25:09 2015] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  [Thu Feb 19 06:25:09 2015]  0000000000000009 ffff880003a11aa0 ffffffff81720eb6 0000000000000000
  [Thu Feb 19 06:25:09 2015]  ffff880003a11ad8 ffffffff810677cd ffff880000c41340 0000000000000000
  [Thu Feb 19 06:25:09 2015]  ffff88000a58e000 ffffffff81835280 0000000000001302 ffff880003a11ae8
  [Thu Feb 19 06:25:09 2015] Call Trace:
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81720eb6>] dump_stack+0x45/0x56
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810677cd>] warn_slowpath_common+0x7d/0xa0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810678aa>] warn_slowpath_null+0x1a/0x20
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126e862>] __ext4_handle_dirty_metadata+0x1a2/0x1c0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81246a5a>] ? ext4_dirty_inode+0x2a/0x60
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81277086>] ext4_free_blocks+0x646/0xbf0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810aacc5>] ? wake_up_bit+0x25/0x30
  [Thu Feb 19 06:25:09 2015]  [<ffffffff812685b5>] ext4_ext_rm_leaf+0x505/0x8f0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81267527>] ? __ext4_ext_check+0x197/0x370
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126ad00>] ? ext4_ext_remove_space+0xc0/0x7e0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126af5c>] ext4_ext_remove_space+0x31c/0x7e0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126d300>] ext4_ext_truncate+0xb0/0xe0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81244eb9>] ext4_truncate+0x379/0x3c0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81245a18>] ext4_evict_inode+0x408/0x4d0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d8f60>] evict+0xb0/0x1b0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d9775>] iput+0xf5/0x180
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d4698>] __dentry_kill+0x1a8/0x200
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d4795>] dput+0xa5/0x180
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811bf7e6>] __fput+0x176/0x260
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811bf91e>] ____fput+0xe/0x10
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810882f7>] task_work_run+0xa7/0xe0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81013ed7>] do_notify_resume+0x97/0xb0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81731c2a>] int_signal+0x12/0x17
  [Thu Feb 19 06:25:09 2015] ---[ end trace ebff9843d81b5c41 ]---
  [Thu Feb 19 06:25:09 2015] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
  [Thu Feb 19 06:25:09 2015] IP: [<ffffffff8125d4c1>] __ext4_error_inode+0x31/0x160
  [Thu Feb 19 06:25:09 2015] PGD 167067 PUD 161067 PMD 0
  [Thu Feb 19 06:25:09 2015] Oops: 0000 [#1] SMP
  [Thu Feb 19 06:25:09 2015] Modules linked in: nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_tcpudp nf_conntrack_ipv4 nf_defrag_ipv4 xt_owner xt_conntrack nf_conntrack iptable_filter ip_tables x_tables serio_raw psmouse floppy
  [Thu Feb 19 06:25:09 2015] CPU: 0 PID: 9946 Comm: logrotate Tainted: G        W     3.13.0-45-generic #74-Ubuntu
  [Thu Feb 19 06:25:09 2015] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  [Thu Feb 19 06:25:09 2015] task: ffff880009ac4800 ti: ffff880003a10000 task.ti: ffff880003a10000
  [Thu Feb 19 06:25:09 2015] RIP: 0010:[<ffffffff8125d4c1>]  [<ffffffff8125d4c1>] __ext4_error_inode+0x31/0x160
  [Thu Feb 19 06:25:09 2015] RSP: 0000:ffff880003a11a58  EFLAGS: 00010292
  [Thu Feb 19 06:25:09 2015] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000086
  [Thu Feb 19 06:25:09 2015] RDX: 0000000000001302 RSI: ffffffff81a6e81f RDI: 0000000000000000
  [Thu Feb 19 06:25:09 2015] RBP: ffff880003a11ae8 R08: ffffffff81a78568 R09: 0000000000000005
  [Thu Feb 19 06:25:09 2015] R10: 00000000ffffffe2 R11: ffff880003a117ce R12: 0000000000000086
  [Thu Feb 19 06:25:09 2015] R13: ffffffff81835280 R14: 0000000000001302 R15: ffffffff81a78568
  [Thu Feb 19 06:25:09 2015] FS:  00007f74eaca4840(0000) GS:ffff88000b800000(0000) knlGS:0000000000000000
  [Thu Feb 19 06:25:09 2015] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  [Thu Feb 19 06:25:09 2015] CR2: 0000000001de4000 CR3: 0000000009b45000 CR4: 00000000000006f0
  [Thu Feb 19 06:25:09 2015] Stack:
  [Thu Feb 19 06:25:09 2015]  ffff880003a11a60 0000000000000103 ebff9843d81b5c41 000000000000321e
  [Thu Feb 19 06:25:09 2015]  00000000000014d8 0000000000000092 000000000000020e ffff88000a58e000
  [Thu Feb 19 06:25:09 2015]  ffff880003a11ae8 ffffffff8126e372 ffffffff810677df ffff880000c41340
  [Thu Feb 19 06:25:09 2015] Call Trace:
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126e372>] ? ext4_journal_abort_handle+0x42/0xc0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810677df>] ? warn_slowpath_common+0x8f/0xa0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126e7cf>] __ext4_handle_dirty_metadata+0x10f/0x1c0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81277086>] ext4_free_blocks+0x646/0xbf0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810aacc5>] ? wake_up_bit+0x25/0x30
  [Thu Feb 19 06:25:09 2015]  [<ffffffff812685b5>] ext4_ext_rm_leaf+0x505/0x8f0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81267527>] ? __ext4_ext_check+0x197/0x370
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126ad00>] ? ext4_ext_remove_space+0xc0/0x7e0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126af5c>] ext4_ext_remove_space+0x31c/0x7e0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff8126d300>] ext4_ext_truncate+0xb0/0xe0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81244eb9>] ext4_truncate+0x379/0x3c0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81245a18>] ext4_evict_inode+0x408/0x4d0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d8f60>] evict+0xb0/0x1b0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d9775>] iput+0xf5/0x180
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d4698>] __dentry_kill+0x1a8/0x200
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811d4795>] dput+0xa5/0x180
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811bf7e6>] __fput+0x176/0x260
  [Thu Feb 19 06:25:09 2015]  [<ffffffff811bf91e>] ____fput+0xe/0x10
  [Thu Feb 19 06:25:09 2015]  [<ffffffff810882f7>] task_work_run+0xa7/0xe0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81013ed7>] do_notify_resume+0x97/0xb0
  [Thu Feb 19 06:25:09 2015]  [<ffffffff81731c2a>] int_signal+0x12/0x17
  [Thu Feb 19 06:25:09 2015] Code: 48 89 e5 41 57 4d 89 c7 41 56 41 89 d6 41 55 49 89 f5 48 c7 c6 1f e8 a6 81 41 54 49 89 cc 53 48 89 fb 48 83 ec 68 4c 89 4c 24 60 <48> 8b 47 28 48 8b 57 40 48 8b 80 f8 02 00 00 48 8b 40 68 89 90
  [Thu Feb 19 06:25:09 2015] RIP  [<ffffffff8125d4c1>] __ext4_error_inode+0x31/0x160
  [Thu Feb 19 06:25:09 2015]  RSP <ffff880003a11a58>
  [Thu Feb 19 06:25:09 2015] CR2: 0000000000000028
  [Thu Feb 19 06:25:10 2015] ---[ end trace ebff9843d81b5c42 ]---

  cron.daily jobs fired at 6:25:01 apparently:

  # tail -n2 /var/log/syslog
  Feb 19 06:17:01 git CRON[9848]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
  Feb 19 06:25:01 git CRON[9853]: (root) CMD (test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily ))

  # run-parts --test /etc/cron.daily
  /etc/cron.daily/apt
  /etc/cron.daily/autoremove
  /etc/cron.daily/dpkg
  /etc/cron.daily/hdd-backup
  /etc/cron.daily/logrotate
  /etc/cron.daily/passwd
  /etc/cron.daily/upstart

  It seems like all the jobs ran and the upstart one somehow triggered
  the crash:

  # ls -alt /var/log/upstart/ | head
  total 272
  drwxrwxr-x 5 root syslog 4096 Feb 19 06:25 ..
  drwxr-xr-x 2 root root   4096 Feb 14 06:25 .
  -rw-r----- 1 root root    591 Feb 12 12:26 ureadahead.log.1.gz
  -rw-r----- 1 root root    178 Feb 12 12:25 mountall.log.1.gz

  Now that I have collected some information (sorry, I don't have
  ubuntu-bug installed on the VM) I'll reboot it and see how it goes.

  More information on the VM:

  # lsb_release -rd
  Description:	Ubuntu 14.04.2 LTS
  Release:	14.04
  # apt-cache policy linux-image-3.13.0-45-generic
  linux-image-3.13.0-45-generic:
    Installed: 3.13.0-45.74
    Candidate: 3.13.0-45.74
    Version table:
   *** 3.13.0-45.74 0
          500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
          100 /var/lib/dpkg/status
  ---
  AlsaDevices:
   total 0
   crw-rw---- 1 root audio 116,  1 Feb 19 14:34 seq
   crw-rw---- 1 root audio 116, 33 Feb 19 14:34 timer
  AplayDevices: Error: [Errno 2] No such file or directory
  ApportVersion: 2.14.1-0ubuntu3.7
  Architecture: amd64
  ArecordDevices: Error: [Errno 2] No such file or directory
  AudioDevicesInUse: Error: [Errno 2] No such file or directory
  CRDA: Error: [Errno 2] No such file or directory
  CurrentDmesg:
   [   13.891047] init: console-font main process (855) terminated with status 71
   [   13.952825] init: plymouth-splash main process (870) terminated with status 1
   [  217.853139] random: nonblocking pool is initialized
  DistroRelease: Ubuntu 14.04
  IwConfig: Error: [Errno 2] No such file or directory
  Lspci: Error: [Errno 2] No such file or directory
  Lsusb: Error: [Errno 2] No such file or directory
  MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
  Package: linux (not installed)
  PciMultimedia:

  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB:

  ProcKernelCmdLine: root=UUID=cb9cbdad-c668-4503-85db-fcf9b02f3495 ro console=tty0 console=ttyS0,38400
  ProcVersionSignature: Ubuntu 3.13.0-45.74-generic 3.13.11-ckt13
  RelatedPackageVersions:
   linux-restricted-modules-3.13.0-45-generic N/A
   linux-backports-modules-3.13.0-45-generic  N/A
   linux-firmware                             N/A
  RfKill: Error: [Errno 2] No such file or directory
  Tags:  trusty
  Uname: Linux 3.13.0-45-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups:

  _MarkForUpload: True
  dmi.bios.date: 01/01/2011
  dmi.bios.vendor: Bochs
  dmi.bios.version: Bochs
  dmi.chassis.type: 1
  dmi.chassis.vendor: Bochs
  dmi.modalias: dmi:bvnBochs:bvrBochs:bd01/01/2011:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-2.0:cvnBochs:ct1:cvr:
  dmi.product.name: Standard PC (i440FX + PIIX, 1996)
  dmi.product.version: pc-i440fx-2.0
  dmi.sys.vendor: QEMU

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References

[Bug 1423672] [NEW] ext4 turned read-only following a cronjob run
From: Simon Déziel, 2015-02-19