[Xen-devel] [Bug] sched: credit2: Assertion failed

[Tianyang Chen <tiche@xxxxxxxxxxxxxx>]

The following script caused an unresponsive dom0 and it can not be 
reproduced all the time. The dom0 is using credit2 scheduler.
#!/bin/bash
xl cpupool-list -c
xl cpupool-cpu-remove Pool-0 3
xl cpupool-cpu-remove Pool-0 2
xl cpupool-create name=\"r\" sched=\"credit\"
xl cpupool-create name=\"t\" sched=\"credit\"
xl cpupool-cpu-add r 3
xl cpupool-cpu-add t 2

Another bug can be reproduced(not all the time) if the newly created 
pool is also credit2. There is an assertion failure (see bug.txt), which 
is essentially the same thing I got when trying to make the new rtds 
scheduler cpupool safe.
With different combinations of schedulers and number of pools created, 
dom0 is either unresponsive or kernel panics.
Since it happens when a pcpu(free) is added to another pool, I'm 
guessing the place to look at is schedule_cpu_switch(), where a series 
of alloc() and free() are called. And indeed at the last free_pdata(), 
the assertion fails.
Both of them happen on 4.7 unstable, git:2e46e3f

Any idea on this is appreciated.

--
Tianyang Chen

Attachment: bug.txt
Description: Text document

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