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Bug 607244 - virtio-blk doesn't load list of pending requests correctly
virtio-blk doesn't load list of pending requests correctly
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: qemu-kvm (Show other bugs)
All Linux
low Severity medium
: rc
: ---
Assigned To: Kevin Wolf
Virtualization Bugs
Depends On:
Blocks: 621501
  Show dependency treegraph
Reported: 2010-06-23 11:38 EDT by Kevin Wolf
Modified: 2013-01-09 17:46 EST (History)
10 users (show)

See Also:
Fixed In Version: qemu-kvm-
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
: 621501 (view as bug list)
Last Closed: 2010-11-10 16:25:39 EST
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Kevin Wolf 2010-06-23 11:38:12 EDT
When loading VM state for virtio-blk, requests are created, but not inserted into the list of pending requests. Therefore they are ignored (and their memory is leaked).
Comment 2 RHEL Product and Program Management 2010-06-23 11:52:52 EDT
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux major release.  Product Management has requested further
review of this request by Red Hat Engineering, for potential inclusion in a Red
Hat Enterprise Linux Major release.  This request is not yet committed for
Comment 9 Shirley Zhou 2010-08-03 00:38:39 EDT
Testing this issue with qemu-kvm-, after i/o error happens on Src guest and guest become paused, then do migration. core dumped happens on Dst guest.

(gdb) bt
#0  virtio_blk_handle_request (req=0x2dea010, mrb=0x7fffe55acf60) at /usr/src/debug/qemu-kvm-
#1  0x000000000041e1cb in virtio_blk_dma_restart_bh (opaque=0x2859d00) at /usr/src/debug/qemu-kvm-
#2  0x0000000000410b5d in qemu_bh_poll () at /usr/src/debug/qemu-kvm-
#3  0x000000000040b5e9 in main_loop_wait (timeout=1000) at /usr/src/debug/qemu-kvm-
#4  0x00000000004289ca in kvm_main_loop () at /usr/src/debug/qemu-kvm-
#5  0x000000000040e47b in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>)
    at /usr/src/debug/qemu-kvm-
#6  main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-
Comment 12 Shirley Zhou 2010-08-05 04:09:31 EDT
Verified this issue with qemu-kvm- as following scenarios:

1.live migration is ok
2.migration via file is ok
3.savevm/loadvm has some problem as following steps:

3.1 install fresh rhel6 guest 
3.2 then run guest
3.3 i/o error, guest become paused
3.4 savevm s1
3.5 (qemu)cont,resume guest
3.6 loadvm s1

error happens after step 3.6:
Error -22 while loading VM state.

Kevin, does it mean we have already fixed this bug? for loadvm issue, is it another problem?
Comment 13 Kevin Wolf 2010-08-05 04:35:35 EDT
These patches fix the crash that you reported in comment 9, so yes, I think it's complete.

You can file a separate bug for the savevm failure, but it's not 6.0 material as we don't support internal snapshots. We might support them for 6.1.
Comment 14 Shirley Zhou 2010-08-05 06:16:23 EDT
Open bug 621501 to track internal snapshot issue.
Change bug status to verified according to comment 12 and comment 13.
Comment 15 releng-rhel@redhat.com 2010-11-10 16:25:39 EST
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.

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