Re: [Qemu-devel] [RFC v3 0/8] Fix QEMU crash during memory hotplug with vhost=on

[Michael S. Tsirkin]

On Wed, Jul 08, 2015 at 01:41:16PM +0200, Igor Mammedov wrote:
> As additional issue:
> deleting backend doesn't actually frees memory since it's
> just mmap(NORESERVE) over allocated region. It's possible
> to do madvise(MADV_DONTNEED) on area but it doesn't guaranty
> that kernel will free memory.

munmap does not guarantee that either.

> So all these mmap/remap
> tricks could screw up mgmt tools if they try to limit memory
> consumed by QEMU.

It's likely easier to manage if virtual memory
usage does not jump up and down randomly.
 
> series is not tested wrt cross-version migration.

Testing is always good but I don't see anything
touching migration here.

-- 
MST