lkml.org 
[lkml]   [2019]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] virtio_balloon: fix pages_to_free calculation
On Mon, Nov 18, 2019 at 01:38:10PM -0800, Khazhismel Kumykov wrote:
> freed_pages was accumulating total freed pages, but was also subtracted
> on each iteration from pages_to_free, which could potentially result in
> attempting to free fewer pages than asked for. This change also makes
> both freed_pages and pages_to_free in terms of "balloon pages", where
> they were mismatched before.

And then patch 2/2 changes it back to both be regular pages.
Which is good, but why do we have to go back and forth
breaking then fixing it back?


>
> Fixes: 71994620bb25 ("virtio_balloon: replace oom notifier with shrinker")
> Cc: Wei Wang <wei.w.wang@intel.com>
> Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
> ---
> drivers/virtio/virtio_balloon.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 226fbb995fb0..7cf9540a40b8 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -782,11 +782,8 @@ static unsigned long shrink_balloon_pages(struct virtio_balloon *vb,
> * VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it
> * multiple times to deflate pages till reaching pages_to_free.
> */
> - while (vb->num_pages && pages_to_free) {
> - pages_freed += leak_balloon(vb, pages_to_free) /
> - VIRTIO_BALLOON_PAGES_PER_PAGE;
> - pages_to_free -= pages_freed;
> - }
> + while (vb->num_pages && pages_to_free > pages_freed)
> + pages_freed += leak_balloon(vb, pages_to_free - pages_freed);
> update_balloon_size(vb);
>
> return pages_freed;
> --
> 2.24.0.432.g9d3f5f5b63-goog

\
 
 \ /
  Last update: 2019-11-18 23:54    [W:0.145 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site