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).
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Testing this issue with qemu-kvm-0.12.1.2-2.104.el6, after i/o error happens on Src guest and guest become paused, then do migration. core dumped happens on Dst guest.
#0 virtio_blk_handle_request (req=0x2dea010, mrb=0x7fffe55acf60) at /usr/src/debug/qemu-kvm-0.12.1.2/hw/virtio-blk.c:332
#1 0x000000000041e1cb in virtio_blk_dma_restart_bh (opaque=0x2859d00) at /usr/src/debug/qemu-kvm-0.12.1.2/hw/virtio-blk.c:388
#2 0x0000000000410b5d in qemu_bh_poll () at /usr/src/debug/qemu-kvm-0.12.1.2/async.c:150
#3 0x000000000040b5e9 in main_loop_wait (timeout=1000) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4244
#4 0x00000000004289ca in kvm_main_loop () at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2133
#5 0x000000000040e47b in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>)
#6 main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:6566
Verified this issue with qemu-kvm-0.12.1.2-2.108.el6 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?
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.
Open bug 621501 to track internal snapshot issue.
Change bug status to verified according to comment 12 and comment 13.
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.