Comment 0 for bug 1217189

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)