David Hildenbrand <[email protected]> writes: > On 02.12.20 17:12, Vitaly Kuznetsov wrote: >> Unlike virtio_balloon/virtio_mem/xen balloon drivers, Hyper-V balloon driver >> does not adjust managed pages count when ballooning/un-ballooning and this >> leads >> to incorrect stats being reported, e.g. unexpected 'free' output. >> >> Note, the calculation in post_status() seems to remain correct: ballooned out >> pages are never 'available' and we manually add dm->num_pages_ballooned to >> 'commited'. >> >> Suggested-by: David Hildenbrand <[email protected]> >> Signed-off-by: Vitaly Kuznetsov <[email protected]> >> --- >> drivers/hv/hv_balloon.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c >> index da3b6bd2367c..8c471823a5af 100644 >> --- a/drivers/hv/hv_balloon.c >> +++ b/drivers/hv/hv_balloon.c >> @@ -1198,6 +1198,7 @@ static void free_balloon_pages(struct hv_dynmem_device >> *dm, >> __ClearPageOffline(pg); >> __free_page(pg); >> dm->num_pages_ballooned--; >> + adjust_managed_page_count(pg, 1); >> } >> } >> >> @@ -1238,8 +1239,10 @@ static unsigned int alloc_balloon_pages(struct >> hv_dynmem_device *dm, >> split_page(pg, get_order(alloc_unit << PAGE_SHIFT)); >> >> /* mark all pages offline */ >> - for (j = 0; j < alloc_unit; j++) >> + for (j = 0; j < alloc_unit; j++) { >> __SetPageOffline(pg + j); >> + adjust_managed_page_count(pg + j, -1); >> + } >> >> bl_resp->range_count++; >> bl_resp->range_array[i].finfo.start_page = >> > > I assume this has been properly tested such that it does not change the > system behavior regarding when/how HyperV decides to add/remove memory. >
I'm always reluctant to confirm 'proper testing' as no matter how small and 'obvious' the change is, regressions keep happening :-) But yes, this was tested on a Hyper-V host and 'stress' and I observed 'free' when the balloon was both inflated and deflated, values looked sane. > LGTM > > Reviewed-by: David Hildenbrand <[email protected]> Thanks! -- Vitaly
