search for: _hint_

...arently do a GFP_KERNEL allocation insider the mm zone > lock, which is broken on just _so_ many levels. Oh, I see the comment about how it doesn't actually do an allocation at all because it's a single-entry. Still too damn ugly to live, and much too fragile. No way in hell do we even _hint_ at a GFP_KERNEL when we're inside a context that can't do any memory allocation at all. Plus I'm not convinced it's a "no allocation" path even despite that comment, because it also does a "dma_map_page()" etc, which can cause allocations to do the dma mapping t...

...arently do a GFP_KERNEL allocation insider the mm zone > lock, which is broken on just _so_ many levels. Oh, I see the comment about how it doesn't actually do an allocation at all because it's a single-entry. Still too damn ugly to live, and much too fragile. No way in hell do we even _hint_ at a GFP_KERNEL when we're inside a context that can't do any memory allocation at all. Plus I'm not convinced it's a "no allocation" path even despite that comment, because it also does a "dma_map_page()" etc, which can cause allocations to do the dma mapping t...

...insider the mm zone > > lock, which is broken on just _so_ many levels. > > Oh, I see the comment about how it doesn't actually do an allocation > at all because it's a single-entry. > > Still too damn ugly to live, and much too fragile. No way in hell do > we even _hint_ at a GFP_KERNEL when we're inside a context that can't > do any memory allocation at all. > > Plus I'm not convinced it's a "no allocation" path even despite that > comment, because it also does a "dma_map_page()" etc, which can cause > allocation...

...the shrinker, (but also to fix Issue 1), it could be that > we do have VIRTIO_BALLOON_F_MUST_TELL_HOST. I don't think it is an issue here. MUST_TELL_HOST is for the ballooning pages, where pages are offered to host to _USE_. For free page hint, as the name already suggests, it's just a _HINT_ , so in whatever use case, the host should not take the page to use. So the guest doesn't need to tell host and wait. Back to the implementation of virtio_balloon_shrinker_scan, which I don't see an issue so far: shrink_free_pages just return pages to mm without waiting for the ack from ho...

On 04.02.20 09:40, Michael S. Tsirkin wrote: > On Tue, Feb 04, 2020 at 09:35:21AM +0100, David Hildenbrand wrote: >>>>> I would say reverting probably makes sense. I'm not sure there is much >>>>> value to having a shrinker running deflation when you are actively trying >>>>> to increase the balloon. It would make more sense to wait until you are

On 04.02.20 09:40, Michael S. Tsirkin wrote: > On Tue, Feb 04, 2020 at 09:35:21AM +0100, David Hildenbrand wrote: >>>>> I would say reverting probably makes sense. I'm not sure there is much >>>>> value to having a shrinker running deflation when you are actively trying >>>>> to increase the balloon. It would make more sense to wait until you are

...to fix Issue 1), it could be that >> we do have VIRTIO_BALLOON_F_MUST_TELL_HOST. > > I don't think it is an issue here. > MUST_TELL_HOST is for the ballooning pages, where pages are offered to host to _USE_. > For free page hint, as the name already suggests, it's just a _HINT_ , so in whatever use case, > the host should not take the page to use. So the guest doesn't need to tell host and wait. Yes, I agree with you. Yet, I am thinking about one (unlikely?impossible?) scenario. Can you refresh my brain why that cannot happen (IOW, why we don't have to wait fo...

...to fix Issue 1), it could be that >> we do have VIRTIO_BALLOON_F_MUST_TELL_HOST. > > I don't think it is an issue here. > MUST_TELL_HOST is for the ballooning pages, where pages are offered to host to _USE_. > For free page hint, as the name already suggests, it's just a _HINT_ , so in whatever use case, > the host should not take the page to use. So the guest doesn't need to tell host and wait. Yes, I agree with you. Yet, I am thinking about one (unlikely?impossible?) scenario. Can you refresh my brain why that cannot happen (IOW, why we don't have to wait fo...

The following changes since commit 29dcea88779c856c7dc92040a0c01233263101d4: Linux 4.17 (2018-06-03 14:15:21 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to aa15783ee62d57d69433101ede3e3ed11e48161d: virtio: update the comments for transport features (2018-06-07 22:17:40 +0300)

The following changes since commit 29dcea88779c856c7dc92040a0c01233263101d4: Linux 4.17 (2018-06-03 14:15:21 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git tags/for_linus for you to fetch changes up to aa15783ee62d57d69433101ede3e3ed11e48161d: virtio: update the comments for transport features (2018-06-07 22:17:40 +0300)