Bug 208172

Summary: kernel dm snapshot: can't create more than 32 snapshots
Product: [Fedora] Fedora Reporter: themoonseeker <themoonseeker>
Component: kernelAssignee: Milan Broz <mbroz>
Status: CLOSED RAWHIDE QA Contact:
Severity: urgent Docs Contact:
Priority: medium    
Version: rawhideCC: agk, brian, dwysocha, mbroz, pvrabec
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
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Clone Of: Environment:
Last Closed: 2007-06-13 17:03:39 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description themoonseeker 2006-09-26 19:03:09 UTC 
Description of problem:
Impossible to create more than 32 snapshots

Version-Release number of selected component (if applicable):
LVM version: 2.02.06 (2006-05-12)
Library version: 1.02.08 (2006-07-17)
Driver version: 4.5.0

How reproducible:


Steps to Reproduce:
1. pvcreate /dev/sda10 
2. vgcreate vg /dev/sda10 
3. lvcreate -L150M -n original vg
4. mkfs -t ext3 /dev/vg/original
5. 33 times this command : 
lvcreate -s -L150M -n copy1 /dev/vg/original
lvcreate -s -L150M -n copy2 /dev/vg/original
...
lvcreate -s -L150M -n copy32 /dev/vg/original
  
Actual results:
root@B03:/diplome# lvcreate -s -L150M -n copy32 /dev/vg/original
  Rounding up size to full physical extent 152.00 MB
  device-mapper: reload ioctl failed: Cannot allocate memory
  Failed to suspend origin original

Expected results:
root@B03:/diplome# lvcreate -s -L150M -n copy32 /dev/vg/original 
  Rounding up size to full physical extent 152.00 MB
  Logical volume "copy32" created

Additional info:
Kernel : uname -r
2.6.16
Comment 1 Milan Broz 2006-12-04 09:17:36 UTC 
Known limitation of DM-IO code waiting for new implementation of dm-io (still
under review)...
Comment 2 Milan Broz 2007-03-14 17:26:30 UTC 
Correcting version & component.
Comment 3 Milan Broz 2007-06-13 16:10:53 UTC 
*** Bug 191531 has been marked as a duplicate of this bug. ***
Comment 4 Milan Broz 2007-06-13 17:03:39 UTC 
This problem is fixed in stable kernel rc releases 2.6.22-rc

Because rawhide uses rc patches, this is already fixed - creating 50 snapshots
with kernel 2.6.21-1.3218.fc8 works ok.