Bug 709268

Summary: Segmentation fault after hot add the 29th virtio disk
Product: Red Hat Enterprise Linux 5 Reporter: Mike Cao <bcao>
Component: kvmAssignee: Virtualization Maintenance <virt-maint>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 5.7CC: juzhang, michen, mkenneth, tburke, virt-maint
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
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Fixed In Version: Doc Type: Bug Fix
Doc Text:
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Clone Of: Environment:
Last Closed: 2011-06-01 11:41:04 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Mike Cao 2011-05-31 08:49:48 UTC
Description of problem:
start a guest with 28 disks ,then hot add 29th virtio disks, seg fault occurs

Version-Release number of selected component (if applicable):
# uname -r
2.6.18-264.el5
# rpm -q kvm
kvm-83-235.el5


How reproducible:
100%

Steps to Reproduce:
1.start guest with e1000 nic & 28 virtio disks (CLI will attached)
2.hot add the 29th virtio disks)
(qemu) pci_add pci_addr=auto storage file=/root/ll28,if=virtio
failed to add file=/root/ll28,if=virtio
(qemu) Segmentation fault (core dumped)

Actual results:

Program terminated with signal 11, Segmentation fault.
#0  qemu_get_clock (clock=0x8200000001)
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/vl.c:1310
1310        switch(clock->type) {
(gdb) bt
#0  qemu_get_clock (clock=0x8200000001)
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/vl.c:1310
#1  0x0000000000409515 in main_loop_wait (timeout=<value optimized out>)
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/vl.c:4134
#2  0x000000000050111a in kvm_main_loop ()
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/qemu-kvm.c:596
#3  0x000000000040e757 in main_loop (argc=93, argv=0x7fff0f664c28, 
    envp=<value optimized out>)
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/vl.c:4157
#4  main (argc=93, argv=0x7fff0f664c28, envp=<value optimized out>)
    at /usr/src/debug/kvm-83-maint-snapshot-20090205/qemu/vl.c:6559

Expected results:
no segmentation fault .it prompts sth like  "could not add 29th disk"

Additional info:

Comment 1 Dor Laor 2011-06-01 11:41:04 UTC
We only have a total of 32 pci devices, some reserved for non disk so you just hit the limit.