Red Hat Bugzilla – Bug 444049
kernel dm snapshot: corruption detected after write to origin volumes
Last modified: 2009-01-08 04:47:13 EST
Description of problem:
I been able to reproduce this issue now quite a few times while running the
4.6.Z regression tests.
I create an origin and a few snapshot volumes. Then with the tool
b_iogen/b_doio, I read the snap, then write to the origin, and verify that the
snap didn't change. I've been seeing that it has however.
The snaps all have the same 32k chunksizes even though their names imply that is
block_snap128 snapper swi-a- 3.50G origin 13.82
block_snap16 snapper swi-a- 3.50G origin 23.31
block_snap256 snapper swi-a- 3.50G origin 8.59
block_snap32 snapper swi-a- 3.50G origin 20.27
block_snap64 snapper swi-a- 3.50G origin 17.32
origin snapper owi-a- 4.00G
[root@taft-01 ~]# /usr/tests/sts-rhel4.6/bin/b_iogen -o -m random -f direct -i
15s -s write,writev -t1000b -T10000b -d
b_iogen starting up with the following:
Single Pass: off
Overlap Flag: on
Syscalls: write writev
*** DATA COMPARISON ERROR /dev/snapper/block_snap256 (Offset 785754112) ***
Started at byte 55296
Expected 0x66(f) 0x74(t) 0x2d(-) 0x30(0) 0x31(1) 0x3a(:) 0x62(b) 0x5f(_) 0x64(d)
Got 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K) 0x4b(K)
Version-Release number of selected component (if applicable):
Is the corruption permanent or transient? After the test finishes and there is no more any IO, do the snapshots contain correct data? Transient corruption is a known problem, there is already fix for upstream. I don't know about any permanent corruption of snapshots with the same chunksize.
Created attachment 304319 [details]
Fix read-realloc race in RHEL 4
Try this patch, if it fixed the test. It is backport for the pending upstream
patch that fixes the read-fs-realloc race condition.
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
This bugzilla has Keywords: Regression.
Since no regressions are allowed between releases,
it is also being proposed as a blocker for this release.
Please resolve ASAP.
Updating PM score.
Resolving as a duplicate of bug #175830 --- it could be duplicate but it is impossible to say certainly without reproducing this bug and further testing. If anyone ever sees this bug after fix for #175830 was applied, reopen it.
*** This bug has been marked as a duplicate of bug 175830 ***