UML: spurious interrupt freezes guest
PATCH 1/1 UML: spurious interrupt freezes guest
A new instance of user mode linux that I created over the past couple of days worked pretty well except that it had a habit of freezing after a few minutes. Every time it froze, the last message on the console was either:
spurious interrupt in ubd_handler, err = 4
or:
spurious interrupt in ubd_handler, err = 0
This message is generated by arch/um/drivers/ubd_kern.c. I did not work out the cause of the spurious interrupts, but I did come up with a patch that makes the guest recover from spurious interrupts without freezing.
It appears that the interrupt handler needs to be reactivated before
every exit of ubd_handler(). The patch is below.
Shane
arch/um/drivers/ubd_kern.c +0 -0
@@ -489,6 +489,7 @@break ; printk(KERN_ERR "spurious interrupt in
ubd_handler, "
"err = %d\n", -n);
+ reactivate_fd(thread_fd, UBD_IRQ);
return;
}------------------------------------------------------------------------------
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Quoted 6 lines · Shane Hathaway
A new instance of user mode linux that I created over the past couple of days worked pretty well except that it had a habit of freezing after a few minutes. Every time it froze, the last message on the console was either:
spurious interrupt in
ubd_handler, err = 4
What version and what's the workload?
Jeff
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Quoted 9 lines · Jeff Dike
Quoted 6 lines · Shane Hathaway
A new instance of user mode linux that I created over the past couple of days worked pretty well except that it had a habit of freezing after a few minutes. Every time it froze, the last message on the console was either:
spurious interrupt in
ubd_handler, err = 4What version and what's the workload?
I got the spurious interrupt with both Linux 2.6.28.1 and 2.6.27.12 as guests. The host runs 2.6.9-42.0.3.ELsmp.
I am putting OpenVPN and Asterisk inside the guest. The guest is based on Ubuntu 8.10. The spurious interrupt happened more often when I restricted the guest's RAM. The processes in the guest normally consume a total of about 20-24 MB of RAM. I limited the guest's RAM to 48 MB and gave it a 64 MB swap partition. When I gave the guest only 32 MB, the spurious interrupt seemed to happen more often.
The best way I found to trigger the spurious interrupt was to try to "apt-get install" many packages at once. The download would succeed, but the guest would freeze partway through the install.
Shane
Quoted 3 lines · Shane Hathaway
The best way I found to trigger the spurious interrupt was to try to "apt-get install" many packages at once. The download would succeed, but the guest would freeze partway through the install.
That makes me think, recently I did an 'apt-get dist-upgrade' on about 10 UMLs at the same time and many of them segfaulted. UMLs are 2.6.26 and host is Fedora 8 32 bits with 1 GB RAM. UMLS have their memory set at 128 MB. I figured I was pushing a bit, so I did not took notes and ended up rebooting the host to get a clean slate.
Al
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