Re: pvh DOMU on NetBSD DOM0 crashes

["Mathew, Cherry G." <c%bow.st@localhost>]

>>>>> On Sun, 14 Apr 2024 19:15:09 +0200, Manuel Bouyer <bouyer%antioche.eu.org@localhost> said:

> On Sun, Apr 14, 2024 at 06:23:02PM +0200, oskar%fessel.org@localhost wrote:
>> Hej,
>> 
>> I ran into a problem with one of my NetBSD DomUs, it always hits the PVH domu with the highest index.
>> 
>> Message in the DOM0:
>> (XEN) p2m_pod_demand_populate: Dom5 out of PoD memory! (tot=131016 ents=131072 dom5)
>> (XEN) domain_crash called from arch/x86/mm/p2m-pod.c:1288
>> (XEN) Domain 5 (vcpu#0) crashed on cpu#0:
>> (XEN) ----[ Xen-4.18.0_20231116nb0  x86_64  debug=n  Not tainted ]----
>> (XEN) CPU:    0
>> (XEN) RIP:    0008:[<ffffffff8023439f>]
>> (XEN) RFLAGS: 0000000000010206   CONTEXT: hvm guest (d5v0)
>> (XEN) rax: 0000000000002800   rbx: 0000000000002800   rcx: 0000000000000200
>> (XEN) rdx: 00007c1cee2ba2c0   rsi: 00007c1cee2b92c0   rdi: ffffc10066592000
>> (XEN) rbp: ffffc100726f2c50   rsp: ffffc100726f2c08   r8:  00007f7ffffff000
>> (XEN) r9:  ffffc100726f2ca0   r10: 000000000000001b   r11: 0000000000000000
>> (XEN) r12: 0000000000002800   r13: ffffc10066590800   r14: ffffc100726f2ee0
>> (XEN) r15: ffffc100726f2ef0   cr0: 0000000080050033   cr4: 00000000001406b0
>> (XEN) cr3: 00000000047d6000   cr2: ffffc10066591000
>> (XEN) fsb: 00007c1cee327850   gsb: ffffffff8183cb00   gss: 0000000000000000
>> (XEN) ds: 0023   es: 0023   fs: 0000   gs: 0000   ss: 0010   cs: 0008
>> (XEN) p2m_pod_demand_populate: Dom5 out of PoD memory! (tot=131016 ents=131072 dom5)
>> (XEN) domain_crash called from arch/x86/mm/p2m-pod.c:1288
>> (XEN) p2m_pod_demand_populate: Dom5 out of PoD memory! (tot=131016 ents=131072 dom5)
>> (XEN) domain_crash called from arch/x86/mm/p2m-pod.c:1288
>> (XEN) p2m_pod_demand_populate: Dom5 out of PoD memory! (tot=131016 ents=131072 dom5)
>> (XEN) domain_crash called from arch/x86/mm/p2m-pod.c:1288
>> 
>> This is XEN 4.18, it happened also on 4.15.  I upgraded to 4.18 because of this ;-)
>> 
>> The config for this DOMU is:
>> ??
>> type = pvh
>> name = "littlejoe"
>> boot = "c"
>> memory = 512
>> maxmem = 1024
>> vcpus = 1
>> vif = [ 'bridge=bridge1', 'bridge=bridge2' ]
>> kernel = "/netbsd-GENERIC.gz"
>> disk = [ '/hurz/joe/xendisklittlejoe,raw,xvda,rw? ]
>> ??
>> 
>> all my pvh domUs run amd64
>> NetBSD 10.99.10 (GENERIC) #2: Fri Dec  8 23:45:08 CET 2023
>> the DOM0 itself is older:
>> NetBSD 10.99.2 (XEN3_DOM0) #0: Tue Dec 27 03:19:40 EET 2022 
>> 
>> The boot.cfg has the following entry:
>> menu=Boot Xen com:load /netbsd-XEN3_DOM0 root=dk6
>> console=com1,115200;multiboot /xen418.gz dom0_mem=32768M
>> dom0_max_vcpus=8 console=com2 com2=115200,8n1,0x2f8
>> 
>> Anything missing there?

> Googling for "out of PoD memory" points to balooning. Using memory == maxmem
> may work around the issue (I set only maxmem in my config files, which
> may explain why I didn't hit the issue).

Is this a situation where, on boot, the balloon demands more memory than
the hypervisor has available ?

-- 
Math/(~cherry)