search for: madv_soft_offlin

From: Alexander Duyck <alexander.h.duyck at linux.intel.com> If we have free page hinting or page reporting enabled we should disable it if the pages are poisoned or initialized on free and we cannot notify the hypervisor. Fixes: 5d757c8d518d ("virtio-balloon: add support for providing free page reports to host") Signed-off-by: Alexander Duyck <alexander.h.duyck at

From: Alexander Duyck <alexander.h.duyck at linux.intel.com> If we have free page hinting or page reporting enabled we should disable it if the pages are poisoned or initialized on free and we cannot notify the hypervisor. Fixes: 5d757c8d518d ("virtio-balloon: add support for providing free page reports to host") Signed-off-by: Alexander Duyck <alexander.h.duyck at

...port, but have no mechanism to report it makes sense to me. The actual likelihood of us encountering this case should be pretty low anyway since it is not that common to have page poisoning or init_on_free enabled. > Yes you can not just drop them but you can maybe do > other things such as MADV_SOFT_OFFLINE. > > Finally, VIRTIO_BALLOON_F_FREE_PAGE_HINT does nothing > at all unless guest gets the command from hypervisor, > so there isn't even any overhead. The problem is we cannot communicate the full situation to the hypervisor without the page poison feature being present. As such I...

...hen it's safe to request hints. As that affects the bitmap, that must not happen in parallel with dirty bitmap handling. Sounds like a reasonable limitation. The hint can be useful outside migration, but in its current form needs to then be non-destructive. E.g. I can imaging userspace calling MADV_SOFT_OFFLINE on the hinted memory. Again a flag that tells guest it should wait until used could be a reasonable expension. If we stick to the shrinker it's actually implementable easily. With an OOM notifier - I'm not so sure ... And a big part of the problem is that after all this time the page hin...

...roviding free page reports to host") > > Signed-off-by: Alexander Duyck <alexander.h.duyck at linux.intel.com> Why not put this logic in the hypervisor? We don't know what hypervisor uses the hints for. Yes you can not just drop them but you can maybe do other things such as MADV_SOFT_OFFLINE. Finally, VIRTIO_BALLOON_F_FREE_PAGE_HINT does nothing at all unless guest gets the command from hypervisor, so there isn't even any overhead. > --- > drivers/virtio/virtio_balloon.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/v...

...t; it makes sense to me. > > The actual likelihood of us encountering this case should be pretty > low anyway since it is not that common to have page poisoning or > init_on_free enabled. > > > Yes you can not just drop them but you can maybe do > > other things such as MADV_SOFT_OFFLINE. > > > > Finally, VIRTIO_BALLOON_F_FREE_PAGE_HINT does nothing > > at all unless guest gets the command from hypervisor, > > so there isn't even any overhead. > > The problem is we cannot communicate the full situation to the > hypervisor without the page pois...

On 05.02.20 10:49, Wang, Wei W wrote: > On Wednesday, February 5, 2020 5:37 PM, David Hildenbrand wrote: >>> >>> Not sure how TCG tracks the dirty bits. But In whatever >>> implementation, the hypervisor should have >> >> There is only a single bitmap for that purpose. (well, the one where KVM >> syncs to) >> >>> already dealt with the

On 05.02.20 10:49, Wang, Wei W wrote: > On Wednesday, February 5, 2020 5:37 PM, David Hildenbrand wrote: >>> >>> Not sure how TCG tracks the dirty bits. But In whatever >>> implementation, the hypervisor should have >> >> There is only a single bitmap for that purpose. (well, the one where KVM >> syncs to) >> >>> already dealt with the