Bug 956180 - kernel periodically logs 'create slab' messages
Summary: kernel periodically logs 'create slab' messages
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 17
Hardware: All
OS: Linux
unspecified
low
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-04-24 12:03 UTC by Ian Donaldson
Modified: 2013-04-25 18:12 UTC (History)
5 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2013-04-25 18:12:34 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)

Description Ian Donaldson 2013-04-24 12:03:34 UTC
Description of problem:

Kernel has started logging these... since we upgraded to kernel 3.8

eg:

Mar 26 17:44:23 frontier kernel: [    0.068253] bio: create slab <bio-0> at 0
Mar 26 17:44:23 frontier kernel: [    7.375913] bio: create slab <bio-1> at 1
Apr 18 12:21:40 frontier kernel: [40021.203102] bio: create slab <bio-2> at 2
Apr 19 11:30:57 frontier kernel: [123378.128225] bio: create slab <bio-1> at 1
Apr 20 09:52:16 frontier kernel: [203856.798226] bio: create slab <bio-1> at 1
Apr 20 09:56:11 frontier kernel: [204092.592733] bio: create slab <bio-1> at 1
Apr 21 12:52:55 frontier kernel: [301096.667498] bio: create slab <bio-1> at 1
Apr 21 12:56:41 frontier kernel: [301321.878257] bio: create slab <bio-1> at 1
Apr 22 11:23:38 frontier kernel: [382138.847549] bio: create slab <bio-1> at 1
Apr 22 11:27:43 frontier kernel: [382384.116224] bio: create slab <bio-1> at 1
Apr 23 11:51:26 frontier kernel: [470207.481219] bio: create slab <bio-1> at 1
Apr 23 11:55:32 frontier kernel: [470453.140264] bio: create slab <bio-1> at 1
Apr 24 11:17:21 frontier kernel: [554561.788225] bio: create slab <bio-1> at 1
Apr 24 11:30:40 frontier kernel: [555360.748224] bio: create slab <bio-1> at 1


Feb  3 08:56:48 hardrock kernel: [    0.110620] bio: create slab <bio-0> at 0
Feb  3 08:56:48 hardrock kernel: [   12.394835] bio: create slab <bio-1> at 1
Feb 25 01:29:37 hardrock kernel: [    0.109628] bio: create slab <bio-0> at 0
Feb 25 01:29:37 hardrock kernel: [   12.250904] bio: create slab <bio-1> at 1
Mar  7 00:00:37 hardrock kernel: [    0.109683] bio: create slab <bio-0> at 0
Mar  7 00:00:37 hardrock kernel: [   12.407370] bio: create slab <bio-1> at 1
Apr 18 01:39:18 hardrock kernel: [    0.109731] bio: create slab <bio-0> at 0
Apr 18 01:39:18 hardrock kernel: [   12.236048] bio: create slab <bio-1> at 1
Apr 18 12:29:41 hardrock kernel: [39199.924450] bio: create slab <bio-2> at 2
Apr 22 11:28:34 hardrock kernel: [381132.287689] bio: create slab <bio-1> at 1
Apr 23 11:56:21 hardrock kernel: [469199.667109] bio: create slab <bio-1> at 1

What does this message mean?  Is it a problem?  Just some debug code
that didn't get turned off?


Our systems monitor unexpected kernel messages hence we noticed them;
I will filter them if they don't indicate a problem lurking...


Version-Release number of selected component (if applicable):

kernel-PAE-3.8.4-102.fc17.i686
kernel-3.8.3-103.fc17.x86_64
kernel-3.8.4-102.fc17.x86_64

How reproducible:

Not on all systems we have.  Most servers.  
Some have software mirroring, others
  have not, some have IDE drives; some have SAS.  

Steps to Reproduce:
1. inspect kernel syslog messages 
2.
3.
  
Actual results:

Message present if there is an issue to be addressed.

Expected results:

No message if nothing is wrong.

Additional info:

Prior kernels (eg: 3.7.9) didn't produce these except for once at boot time

Comment 1 Dave Jones 2013-04-25 18:12:34 UTC
this is just informational.

as far as I can tell this logging indicates that the block layer started using incrementally larger allocations.  bio-0 = 4k, bio-1 = 8k, bio-2 = 16k etc..


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