search for: release_pages_balloon

...turn pfn_to_page(pfn / VIRTIO_BALLOON_PAGES_PER_PAGE); -} - static void balloon_ack(struct virtqueue *vq) { struct virtio_balloon *vb = vq->vdev->priv; @@ -181,18 +175,16 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) return num_allocated_pages; } -static void release_pages_balloon(struct virtio_balloon *vb) +static void release_pages_balloon(struct virtio_balloon *vb, + struct list_head *pages) { - unsigned int i; - struct page *page; + struct page *page, *next; - /* Find pfns pointing at start of each page, get pages and free them. */ - for (i = 0; i < vb->num_...

Though there is a problem in this setup. The end-user and hosting provider have signed SLA agreement in which some amount of memory is guaranted for the guest. The good thing is that this memory will be given to the guest when the guest will really need it (f.e. with OOM in guest and with VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing is that end-user does not know this.

Though there is a problem in this setup. The end-user and hosting provider have signed SLA agreement in which some amount of memory is guaranted for the guest. The good thing is that this memory will be given to the guest when the guest will really need it (f.e. with OOM in guest and with VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing is that end-user does not know this.

...t > } > That means we have to allocate/free all the requested pages first, and then tell the host. It works fine for inflating, but for deflating, because the page has been deleted from the vb-> vb_dev_info->pages, so, we have to use a struct to save the dequeued pages before calling release_pages_balloon(), I think a page bitmap is the best struct to save these pages, because it consumes less memory. And that bitmap should be large enough to save pfn 0 to max_pfn. If the above is true, then we are back to the square one. we really need a large page bitmap. Right? Liang

...t > } > That means we have to allocate/free all the requested pages first, and then tell the host. It works fine for inflating, but for deflating, because the page has been deleted from the vb-> vb_dev_info->pages, so, we have to use a struct to save the dequeued pages before calling release_pages_balloon(), I think a page bitmap is the best struct to save these pages, because it consumes less memory. And that bitmap should be large enough to save pfn 0 to max_pfn. If the above is true, then we are back to the square one. we really need a large page bitmap. Right? Liang

During my compaction-related stuff, I encountered a bug with ballooning. With repeated inflating and deflating cycle, guest memory( ie, cat /proc/meminfo | grep MemTotal) is decreased and couldn't be recovered. The reason is balloon_lock doesn't cover release_pages_balloon so struct virtio_balloon fields could be overwritten by race of fill_balloon(e,g, vb->*pfns could be critical). This patch fixes it in my test. Cc: <stable at vger.kernel.org> Signed-off-by: Minchan Kim <minchan at kernel.org> --- drivers/virtio/virtio_balloon.c | 2 +- 1 file cha...

During my compaction-related stuff, I encountered a bug with ballooning. With repeated inflating and deflating cycle, guest memory( ie, cat /proc/meminfo | grep MemTotal) is decreased and couldn't be recovered. The reason is balloon_lock doesn't cover release_pages_balloon so struct virtio_balloon fields could be overwritten by race of fill_balloon(e,g, vb->*pfns could be critical). This patch fixes it in my test. Cc: <stable at vger.kernel.org> Signed-off-by: Minchan Kim <minchan at kernel.org> --- drivers/virtio/virtio_balloon.c | 2 +- 1 file cha...

...; > + atomic64_add(num_pfns, &vb->num_pages); Isn't this addition too late? If leak_balloon() is called due to out_of_memory(), it will fail to find up to dated vb->num_pages value. > > - return num_allocated_pages; > + return num_pfns; > } > > static void release_pages_balloon(struct virtio_balloon *vb, > @@ -194,38 +192,39 @@ static void release_pages_balloon(struct virtio_balloon *vb, > > static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > { > - unsigned num_freed_pages; > struct page *page; > struct balloon_dev_info *vb_d...

...; > + atomic64_add(num_pfns, &vb->num_pages); Isn't this addition too late? If leak_balloon() is called due to out_of_memory(), it will fail to find up to dated vb->num_pages value. > > - return num_allocated_pages; > + return num_pfns; > } > > static void release_pages_balloon(struct virtio_balloon *vb, > @@ -194,38 +192,39 @@ static void release_pages_balloon(struct virtio_balloon *vb, > > static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > { > - unsigned num_freed_pages; > struct page *page; > struct balloon_dev_info *vb_d...

...t; During my compaction-related stuff, I encountered a bug > with ballooning. > > With repeated inflating and deflating cycle, guest memory( > ie, cat /proc/meminfo | grep MemTotal) is decreased and > couldn't be recovered. > > The reason is balloon_lock doesn't cover release_pages_balloon > so struct virtio_balloon fields could be overwritten by race > of fill_balloon(e,g, vb->*pfns could be critical). > > This patch fixes it in my test. > > Cc: <stable at vger.kernel.org> > Signed-off-by: Minchan Kim <minchan at kernel.org> > --- > drive...

...vb, vb->inflate_vq); - mutex_unlock(&vb->balloon_lock); + if (num_pfns != 0) + tell_host(vb, vb->inflate_vq, pfns, num_pfns); + mutex_unlock(&vb->inflate_lock); + atomic64_add(num_pfns, &vb->num_pages); - return num_allocated_pages; + return num_pfns; } static void release_pages_balloon(struct virtio_balloon *vb, @@ -194,38 +192,39 @@ static void release_pages_balloon(struct virtio_balloon *vb, static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) { - unsigned num_freed_pages; struct page *page; struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info;...

...; + if (use_bmap) > + set_page_bitmap(vb, &vb_dev_info->pages, > + vb->inflate_vq); > + else > + tell_host(vb, vb->inflate_vq); > + } > mutex_unlock(&vb->balloon_lock); > > return num_allocated_pages; > @@ -189,15 +338,19 @@ static void release_pages_balloon(struct virtio_balloon *vb, > } > } > > -static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > +static unsigned int leak_balloon(struct virtio_balloon *vb, size_t num, > + bool use_bmap) this is just a feature bit - why not get it internally? > { >...

...; + if (use_bmap) > + set_page_bitmap(vb, &vb_dev_info->pages, > + vb->inflate_vq); > + else > + tell_host(vb, vb->inflate_vq); > + } > mutex_unlock(&vb->balloon_lock); > > return num_allocated_pages; > @@ -189,15 +338,19 @@ static void release_pages_balloon(struct virtio_balloon *vb, > } > } > > -static unsigned leak_balloon(struct virtio_balloon *vb, size_t num) > +static unsigned int leak_balloon(struct virtio_balloon *vb, size_t num, > + bool use_bmap) this is just a feature bit - why not get it internally? > { >...

...ned fill_balloon_pfns(struct virtio_balloon *vb, size_t num) { struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; unsigned num_allocated_pages; @@ -174,7 +244,104 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) return num_allocated_pages; } -static void release_pages_balloon(struct virtio_balloon *vb) +static long fill_balloon_bitmap(struct virtio_balloon *vb, size_t num) +{ + struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; + long num_allocated_pages = 0; + + if (balloon_page_bitmap_init(vb) < 0) + return num; + + mutex_lock(&vb->balloon_lock...

...ned fill_balloon_pfns(struct virtio_balloon *vb, size_t num) { struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; unsigned num_allocated_pages; @@ -174,7 +244,104 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) return num_allocated_pages; } -static void release_pages_balloon(struct virtio_balloon *vb) +static long fill_balloon_bitmap(struct virtio_balloon *vb, size_t num) +{ + struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; + long num_allocated_pages = 0; + + if (balloon_page_bitmap_init(vb) < 0) + return num; + + mutex_lock(&vb->balloon_lock...

...> That means we have to allocate/free all the requested pages first, and then tell the host. > It works fine for inflating, but for deflating, because the page has been deleted from the vb-> vb_dev_info->pages, > so, we have to use a struct to save the dequeued pages before calling release_pages_balloon(), struct list_head? I think you can just replace set_page_pfns with list_add(&page->lru, &page_list); > I think a page bitmap is the best struct to save these pages, because it consumes less memory. > And that bitmap should be large enough to save pfn 0 to max_pfn. &...

...struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; > > unsigned num_allocated_pages; > > @@ -174,7 +244,104 @@ static unsigned fill_balloon(struct virtio_balloon > *vb, size_t num) > > return num_allocated_pages; > > } > > > > -static void release_pages_balloon(struct virtio_balloon *vb) > > +static long fill_balloon_bitmap(struct virtio_balloon *vb, size_t > > +num) { > > + struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; > > + long num_allocated_pages = 0; > > + > > + if (balloon_page_bitmap_init(vb) &l...

...struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; > > unsigned num_allocated_pages; > > @@ -174,7 +244,104 @@ static unsigned fill_balloon(struct virtio_balloon > *vb, size_t num) > > return num_allocated_pages; > > } > > > > -static void release_pages_balloon(struct virtio_balloon *vb) > > +static long fill_balloon_bitmap(struct virtio_balloon *vb, size_t > > +num) { > > + struct balloon_dev_info *vb_dev_info = &vb->vb_dev_info; > > + long num_allocated_pages = 0; > > + > > + if (balloon_page_bitmap_init(vb) &l...

This patchset is for kernel and contains two parts of change to the virtio-balloon. One is the change for speeding up the inflating & deflating process, the main idea of this optimization is to use bitmap to send the page information to host instead of the PFNs, to reduce the overhead of virtio data transmission, address translation and madvise(). This can help to improve the performance by

This patchset is for kernel and contains two parts of change to the virtio-balloon. One is the change for speeding up the inflating & deflating process, the main idea of this optimization is to use bitmap to send the page information to host instead of the PFNs, to reduce the overhead of virtio data transmission, address translation and madvise(). This can help to improve the performance by