[Qemu-devel] [Bug 1013241] [NEW] qemu-system-ppc64 hanging occasionally in disk writes

[Richard W.M. Jones]

Public bug reported:

I found last week that qemu-system-ppc64 (from git) hangs occasionally          
under load, and I have a reproducer for it now.  Unfortunately the              
reproducer really takes a long time to run -- usually I can get a hang          
in under 12 hours.                                                              
                                                                                
Here is the reproducer case:                                                    
                                                                                
  https://lists.fedoraproject.org/pipermail/ppc/2012-June/001698.html           
                                                                                
Notes:                                                                          
                                                                                
(1) Verified by one other person (other than me).  Happens on both              
    ppc64 and x86-64 host.                                                      
                                                                                
(2) Happens with both Fedora guest kernel 3.3.4-5.fc17.ppc64 and kernel         
    3.5.0 that I compiled myself.  The test case above contains 3.3.4-5.        
                                                                                
(3) Seems to be a problem in qemu, not the guest.  The reason I think           
    this is because I tried to capture a backtrace of the hang using            
    remote gdb, but gdb just hung when trying to connect to qemu                
    (gdb connects fine before the bug happens).                                 
                                                                                
(4) Judging by guest messages, appears to be happening when writing             
    to the disk.

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1013241

Title:
  qemu-system-ppc64 hanging occasionally in disk writes

Status in QEMU:
  New

Bug description:
  I found last week that qemu-system-ppc64 (from git) hangs occasionally        
  
  under load, and I have a reproducer for it now.  Unfortunately the            
  
  reproducer really takes a long time to run -- usually I can get a hang        
  
  in under 12 hours.                                                            
  
                                                                                
  
  Here is the reproducer case:                                                  
  
                                                                                
  
    https://lists.fedoraproject.org/pipermail/ppc/2012-June/001698.html         
  
                                                                                
  
  Notes:                                                                        
  
                                                                                
  
  (1) Verified by one other person (other than me).  Happens on both            
  
      ppc64 and x86-64 host.                                                    
  
                                                                                
  
  (2) Happens with both Fedora guest kernel 3.3.4-5.fc17.ppc64 and kernel       
  
      3.5.0 that I compiled myself.  The test case above contains 3.3.4-5.      
  
                                                                                
  
  (3) Seems to be a problem in qemu, not the guest.  The reason I think         
  
      this is because I tried to capture a backtrace of the hang using          
  
      remote gdb, but gdb just hung when trying to connect to qemu              
  
      (gdb connects fine before the bug happens).                               
  
                                                                                
  
  (4) Judging by guest messages, appears to be happening when writing           
  
      to the disk.

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