[Xen-devel] Memory allocation going seriously wonky on 4.1.1

[Anthony Wright <anthony@xxxxxxxxxxxxxxx>]

I have a machine with 16GB of RAM running 32 bit xen 4.1.1 with Dom0
running a 3.0.4 linux kernel and 23 paravirtualized DomUs.

As the free ram gets to 2391 MB free the system behaves as if it's got
no more ram, and starts grabbing ram from Dom0, before getting even more
confused and failing to start DomUs and eventually crashing the whole
machine. I have attached a tarball with the output of xl dmesg, xl info
& xl list at various points.

Stage 1
Everything is fine, Dom0 has 2000MB according to xl list, and 'xl info'
says there is 2405MB free.

Stage 2
I have increased the memory for the DomU labelled 10-4 from 700MB to
1000MB, Dom0 has 1713MB and 'xl info' says there is 2391MB free.

Stage 3
I have tried to increase the memory for the DomU labelled 13-4 from
700MB to 1000MB, but it failed on the 'xl create' displaying the message
'failed to free memory for the domain'. Dom0 has 1413MB and 'xl info'
says there is 3391MB free.

State 4
I tried to create the 13-4 DomU again, and this time it succeeds. Dom0
has 1413MB and 'xl info' says there is 2391MB free.

If I repeatedly stop and start DomUs at this point, particularly if I
request more ram, the machine locks up. This may be due to lack of Dom0 ram.

Attachment: vm-memory-logs.tar.bz2
Description: Binary data

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