[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCHv1] xen/balloon: disable memory hotplug in PV guests
On 03/11/2015 10:42 AM, David Vrabel wrote: On 10/03/15 13:35, Boris Ostrovsky wrote:On 03/10/2015 07:40 AM, David Vrabel wrote:On 09/03/15 14:10, David Vrabel wrote:Memory hotplug doesn't work with PV guests because: a) The p2m cannot be expanded to cover the new sections.Broken by 054954eb051f35e74b75a566a96fe756015352c8 (xen: switch to linear virtual mapped sparse p2m list). This one would be non-trivial to fix. We'd need a sparse set of vm_area's for the p2m or similar.b) add_memory() builds page tables for the new sections which means the new pages must have valid p2m entries (or a BUG occurs).After some more testing this appears to be broken by: 25b884a83d487fd62c3de7ac1ab5549979188482 (x86/xen: set regions above the end of RAM as 1:1) included 3.16. This one can be trivially fixed by setting the new sections in the p2m to INVALID_P2M_ENTRY before calling add_memory().Have you tried 3.17? As I said yesterday, it worked for me (with 4.4 Xen).No. But there are three bugs that prevent it from working in 3.16+ so I'm really not sure how you had a working in a 3.17 PV guest. This is what I have:[build@build-mk2 linux-boris]$ ssh root@tst008 cat /mnt/lab/bootstrap-x86_64/test_small.xm extra="console=hvc0 debug earlyprintk=xen " kernel="/mnt/lab/bootstrap-x86_64/vmlinuz" ramdisk="/mnt/lab/bootstrap-x86_64/initramfs.cpio.gz" memory=1024 maxmem = 4096 vcpus=1 maxvcpus=3 name="bootstrap-x86_64" on_crash="preserve" vif = [ 'mac=00:0F:4B:00:00:68, bridge=switch' ] vnc=1 vnclisten="0.0.0.0" disk=['phy:/dev/guests/bootstrap-x86_64,xvda,w'][build@build-mk2 linux-boris]$ ssh root@tst008 xl create /mnt/lab/bootstrap-x86_64/test_small.xm Parsing config from /mnt/lab/bootstrap-x86_64/test_small.xm[build@build-mk2 linux-boris]$ ssh root@tst008 xl list |grep bootstrap-x86_64 bootstrap-x86_64 2 1024 1 -b---- 5.4 [build@build-mk2 linux-boris]$ ssh root@g-pvops uname -r 3.17.0upstream [build@build-mk2 linux-boris]$ ssh root@g-pvops dmesg|grep paravirtualized [ 0.000000] Booting paravirtualized kernel on Xen [build@build-mk2 linux-boris]$ ssh root@g-pvops grep MemTotal /proc/meminfo MemTotal: 968036 kB[build@build-mk2 linux-boris]$ ssh root@tst008 xl mem-set bootstrap-x86_64 2048 [build@build-mk2 linux-boris]$ ssh root@tst008 xl list |grep bootstrap-x86_64 bootstrap-x86_64 2 2048 1 -b---- 5.7 [build@build-mk2 linux-boris]$ ssh root@g-pvops grep MemTotal /proc/meminfo MemTotal: 2016612 kB [build@build-mk2 linux-boris]$ Regardless, it definitely doesn't work now because of the linear p2m change. What do you want to do about this? Since backing out p2m changes is not an option I guess your patch is the only short-term alternative. But this still looks like a regression so perhaps Juergen can take a look to see how it can be fixed. -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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