kernel-packages team mailing list archive

[Steve Dodd <1217189@xxxxxxxxxxxxxxxxxx>]

Hence why I said I/O errors on *write*. If the block dev layer reports
an error to the VM on page-out, it knows the data hasn't been correctly
written.

I'm not sure zram actually allocates the whole amount of memory it's
configured to use, initially:

steved@xubuntu:~$ free
             total       used       free     shared    buffers cached
Mem:       2050796    1473456     577340          0     254232 696144
-/+ buffers/cache:     523080    1527716
Swap:      2975088      20848    2954240
steved@xubuntu:~$ swapon -s
Filename				Type		Size	Used Priority
/dev/zram0                              partition	1025396	20848 100
/dev/mapper/lvg2-swap                   partition	1949692	0 -1

At the very least, free seems to know it's cache memory. Don't know
whether that's merely a presentation thing, need to look at the code.

Anyway, the SNR here is getting awful, and I don't want to contribute to
it. Anyone who wants to can contact me privately via LP.

S.

On Fri, Oct 04, 2013 at 03:28:18PM -0000, Kenneth Parker wrote:
> Mel, the reason I do NOT believe this is a duplicate of # 1215513 is
> that many get error messages (including I/O errors in some cases)
> WITHOUT a hang.  But any time I see I/O error on any disk, whether
> "hardware, ram or simulated [i.e. network]", there's a chance of data
> corruption, even without crashes.  Please reconsider.
> 
> Steve, you also mention I/O error messages.  Once again, that could
> corrupt data, the WORST TYPE of error, in my NOT SO humble opinion.
> (Think about it:  If SWAP data comes back in, and your "bank balance"
> changes from 5000 to 500,000, you might THINK you have more in your
> account than you do, causing "mishaps" in International Finance.
> [Example used, due to how badly your life could be hurt].
> 
> My personal solution is to come up with ONLY a Root Text console [yes,
> Ubuntu users aren't SUPPOSED to become "real Root", but I've been doing
> this sort of thing since the 1990's], "rmmod zram" [with prejudice, if
> possible], and I'm prepared to do a "permanent rename" of the correct
> name of the module, as soon as I "get around" to it.  [Visions of Round
> Tuits...]
> 
> A point I made earlier:  Even if a SWAP partition is NOT made out of
> /dev/zram0, part of RAM is being "reserved for nothing".
> 
> Thank you and best regards,
> 
> Kenneth Parker, Seattle, WA
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1217189
> 
> Title:
>   Buffer I/O error on device zram0
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1217189/+subscriptions

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https://bugs.launchpad.net/bugs/1217189

Title:
  Buffer I/O error on device zram0

Status in “linux” package in Ubuntu:
  Confirmed
Status in “linux-lts-raring” package in Ubuntu:
  Confirmed

Bug description:
  This is on linux-image-generic-lts-raring (which I recently upgraded
  to 3.8.0-29; the problem didn't occur before upgrading AFAIR)

  I see this junk in my dmesg when creating / formatting a zram swap,
  and then periodically. Then at some point after heavy swapping
  incidents, the machine locks up. "Correlation does not imply
  causation, but it does waggle its eyebrows suggestively" and all that.

  ---

  zram: module is from the staging directory, the quality is unknown, you have been warned.
  zram: num_devices not specified. Using default: 1
  zram: Creating 1 devices
  Adding 1031648k swap on /dev/zram0.  Priority:100 extents:1 across:1031648k SS
  ...
  Buffer I/O error on device zram0, logical block 257912 [repeated 10 times]
  ...
  BUG: scheduling while atomic: rsyslogd/1439/0x00000001
  Pid: 1439, comm: rsyslogd Tainted: PF       WC O 3.8.0-29-generic #42~precise1-Ubuntu
  [20931.796635] Pid: 1439, comm: rsyslogd Tainted: PF       WC O 3.8.0-29-generic #42~precise1-Ubuntu
  [20931.796638] Call Trace:
  [20931.796649]  [<c1619449>] __schedule_bug+0x52/0x5e
  [20931.796653]  [<c162c265>] __schedule+0x575/0x5f0
  [20931.796660]  [<f8439e06>] ? zram_make_request+0xe6/0x100 [zram]
  [20931.796666]  [<c111c38d>] ? release_pages+0x18d/0x1c0
  [20931.796669]  [<c162c573>] schedule+0x23/0x60
  [20931.796673]  [<c162d0fd>] rwsem_down_failed_common+0x9d/0xf0
  [20931.796677]  [<c162d162>] rwsem_down_write_failed+0x12/0x20
  [20931.796681]  [<c12f809a>] call_rwsem_down_write_failed+0x6/0x8
  [20931.796685]  [<c162ba44>] ? down_write+0x24/0x30
  [20931.796689]  [<f8439169>] zram_slot_free_notify+0x29/0x50 [zram]
  [20931.796693]  [<f8439140>] ? zram_stat64_inc+0x30/0x30 [zram]
  [20931.796700]  [<c11460bc>] swap_entry_free+0xdc/0x170
  [20931.796703]  [<c162d100>] ? rwsem_down_failed_common+0xa0/0xf0
  [20931.796708]  [<c1146458>] swap_free+0x28/0x40
  [20931.796712]  [<c1134ba0>] do_swap_page+0x390/0x6f0
  [20931.796717]  [<c10180f8>] ? sched_clock+0x8/0x10
  [20931.796721]  [<c11365aa>] handle_pte_fault+0x21a/0x2b0
  [20931.796726]  [<c10451e1>] ? kmap_atomic_prot+0xf1/0x120
  [20931.796730]  [<c113746a>] handle_mm_fault+0x1fa/0x2d0
  [20931.796735]  [<c1630ad0>] __do_page_fault+0x190/0x4f0
  [20931.796740]  [<c12f63bc>] ? sprintf+0x1c/0x20
  [20931.796744]  [<c104c132>] ? print_time.part.4+0x82/0xc0
  [20931.796748]  [<c1630e30>] ? __do_page_fault+0x4f0/0x4f0
  [20931.796752]  [<c1630e3d>] do_page_fault+0xd/0x10
  [20931.796756]  [<c162dc17>] error_code+0x67/0x6c
  [20931.796759]  [<c12f8716>] ? __copy_to_user_ll+0x46/0x70
  [20931.796763]  [<c12f8970>] copy_to_user+0x40/0x60
  [20931.796767]  [<c104e218>] syslog_print+0xc8/0x210
  [20931.796770]  [<c104eae6>] do_syslog+0x206/0x390
  [20931.796775]  [<c106d570>] ? add_wait_queue+0x50/0x50
  [20931.796780]  [<c11c3680>] ? kmsg_poll+0x50/0x50
  [20931.796784]  [<c11c36d0>] kmsg_read+0x50/0x60
  [20931.796788]  [<c11b6584>] proc_reg_read+0x64/0xa0
  [20931.796793]  [<c116469c>] vfs_read+0x8c/0x160
  [20931.796797]  [<c10a898d>] ? sys_futex+0xed/0x130
  [20931.796801]  [<c11b6520>] ? proc_reg_write+0xa0/0xa0
  [20931.796805]  [<c11647b7>] sys_read+0x47/0x80
  ...
  [30855.181542] Write-error on swap-device (251:0:131064)
  [43457.030155] Write-error on swap-device (251:0:131064)
  [43705.090381] Buffer I/O error on device zram0, logical block 16383

  Anyway, there's a couple of lkml messages related to this "Buffer I/O
  error on device zram0", please investigate

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: linux-image-3.8.0-29-generic 3.8.0-29.42~precise1
  ProcVersionSignature: Ubuntu 3.8.0-29.42~precise1-generic 3.8.13.5
  Uname: Linux 3.8.0-29-generic i686
  NonfreeKernelModules: nvidia
  ApportVersion: 2.0.1-0ubuntu17.4
  Architecture: i386
  Date: Tue Aug 27 07:33:37 2013
  EcryptfsInUse: Yes
  MarkForUpload: True
  ProcEnviron:
   TERM=rxvt
   LC_COLLATE=C
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: linux-lts-raring
  UpgradeStatus: No upgrade log present (probably fresh install)
  --- 
  AlsaVersion: Advanced Linux Sound Architecture Driver Version k3.8.0-29-lowlatency.
  ApportVersion: 2.0.1-0ubuntu17.4
  Architecture: i386
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  muresan   29305 F.... pulseaudio
   /dev/snd/pcmC0D0p:   muresan   29305 F...m pulseaudio
   /dev/snd/controlC1:  muresan   29305 F.... pulseaudio
  CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
  Card0.Amixer.info:
   Card hw:0 'Intel'/'HDA Intel at 0xfebfc000 irq 44'
     Mixer name	: 'SigmaTel STAC9205'
     Components	: 'HDA:838476a0,102801f1,00100204 HDA:14f12c06,14f1000f,00100000'
     Controls      : 26
     Simple ctrls  : 12
  Card1.Amixer.info:
   Card hw:1 'USB'/'E-MU Systems, Inc. E-MU 0202 | USB at usb-0000:00:1d.0-2, full speed'
     Mixer name	: 'USB Mixer'
     Components	: 'USB041e:3f02'
     Controls      : 4
     Simple ctrls  : 2
  DistroRelease: Ubuntu 12.04
  EcryptfsInUse: Yes
  HibernationDevice: RESUME=UUID=88836c66-16ea-407f-8753-3190c09ca82f
  IwConfig:
   lo        no wireless extensions.
   
   eth0      no wireless extensions.
  MachineType: Dell Inc. Inspiron 1520
  MarkForUpload: True
  NonfreeKernelModules: nvidia
  Package: linux-lts-raring
  ProcEnviron:
   TERM=rxvt
   LC_COLLATE=C
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcFB:
   
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-29-lowlatency root=UUID=a7047dd8-61aa-4cbe-b36d-697a5e7ee64b ro
  ProcVersionSignature: Ubuntu 3.8.0-29.21-lowlatency 3.8.13.5
  RelatedPackageVersions:
   linux-restricted-modules-3.8.0-29-lowlatency N/A
   linux-backports-modules-3.8.0-29-lowlatency  N/A
   linux-firmware                               1.79.6
  RfKill:
   0: hci0: Bluetooth
   	Soft blocked: no
   	Hard blocked: no
  StagingDrivers: zram
  Tags:  precise staging
  Uname: Linux 3.8.0-29-lowlatency i686
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm admin audio cdrom davfs2 dialout dip floppy fuse lpadmin netdev plugdev powerdev sambashare scanner video
  dmi.bios.date: 02/03/2008
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A07
  dmi.board.name: 0UW306
  dmi.board.vendor: Dell Inc.
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA07:bd02/03/2008:svnDellInc.:pnInspiron1520:pvr:rvnDellInc.:rn0UW306:rvr:cvnDellInc.:ct8:cvr:
  dmi.product.name: Inspiron 1520
  dmi.sys.vendor: Dell Inc.

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