Hi,

I think we also want this patch in the 5.15 stable. Without this patch, hv_balloon() will report incorrect memory usage to hypervisor when running on ARM64 with PAGE_SIZE > 4k. Only 5.15 needs this because ARM64 support of HyperV guests arrived in 5.15.

Upstream id b3d6dd09ff00fdcf4f7c0cb54700ffd5dd343502

Cc: stable@vger.kernel.org # 5.15.x

Thanks!

Regards, Boqun

On Fri, Mar 25, 2022 at 10:32:11AM +0800, Boqun Feng wrote:

DM_STATUS_REPORT expects the numbers of pages in the unit of 4k pages (HV_HYP_PAGE) instead of guest pages, so to make it work when guest page sizes are larger than 4k, convert the numbers of guest pages into the numbers of HV_HYP_PAGEs.

Note that the numbers of guest pages are still used for tracing because tracing is internal to the guest kernel.

Reported-by: Vitaly Kuznetsov vkuznets@redhat.com Signed-off-by: Boqun Feng boqun.feng@gmail.com Reviewed-by: Michael Kelley mikelley@microsoft.com

---

drivers/hv/hv_balloon.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index f2d05bff4245..062156b88a87 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -17,6 +17,7 @@ #include <linux/slab.h> #include <linux/kthread.h> #include <linux/completion.h> +#include <linux/count_zeros.h> #include <linux/memory_hotplug.h> #include <linux/memory.h> #include <linux/notifier.h> @@ -1130,6 +1131,7 @@ static void post_status(struct hv_dynmem_device *dm) struct dm_status status; unsigned long now = jiffies; unsigned long last_post = last_post_time;

• unsigned long num_pages_avail, num_pages_committed;

if (pressure_report_delay > 0) { --pressure_report_delay; @@ -1154,16 +1156,21 @@ static void post_status(struct hv_dynmem_device *dm) * num_pages_onlined) as committed to the host, otherwise it can try * asking us to balloon them out. */

• status.num_avail = si_mem_available();
• status.num_committed = vm_memory_committed() +

• num_pages_avail = si_mem_available();
• num_pages_committed = vm_memory_committed() + dm->num_pages_ballooned + (dm->num_pages_added > dm->num_pages_onlined ? dm->num_pages_added - dm->num_pages_onlined : 0) + compute_balloon_floor();

• trace_balloon_status(status.num_avail, status.num_committed,

• trace_balloon_status(num_pages_avail, num_pages_committed, vm_memory_committed(), dm->num_pages_ballooned, dm->num_pages_added, dm->num_pages_onlined);
• /* Convert numbers of pages into numbers of HV_HYP_PAGEs. */
• status.num_avail = num_pages_avail * NR_HV_HYP_PAGES_IN_PAGE;
• status.num_committed = num_pages_committed * NR_HV_HYP_PAGES_IN_PAGE;
• /*
  • If our transaction ID is no longer current, just don't
  • send the status. This can happen if we were interrupted

-- 2.35.1