On 9/19/23 06:50, Michal Prívozník wrote:
On 9/18/23 19:16, Jim Fehlig wrote:
When Domain-0 autoballooning is enabled, it's possible that memory may
need to be ballooned down in Domain-0 to accommodate the needs of another
virtual machine. libxlDomainFreeMemory handles this task, but due to a
logic bug is underflowing the variable containing Domain-0 new
target memory. The resulting huge numbers are filtered by
libxlSetMemoryTargetWrapper and memory is not changed.
Under the covers, libxlDomainFreeMemory uses Xen's libxl_set_memory_target
API, which includes a 'relative' parameter for specifying how to set the
target. If true, the target is an increment/decrement value over the
current memory, otherwise target is taken as an absolute value.
libxlDomainFreeMemory sets 'relative' to true, but never allows for
negative values by declaring the target memory variable as an unsigned.
Fix by declaring the variable as signed, which also requried adjusting
libxlSetMemoryTargetWrapper.
Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
src/libxl/libxl_api_wrapper.h | 16 ++++++----------
src/libxl/libxl_domain.c | 2 +-
2 files changed, 7 insertions(+), 11 deletions(-)
Reviewed-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
Thanks! Before pushing I also ensured the autoballoon logic is working as
expected. I don't have any automated tests for that since autoballoon has not
been enabled in SUSE distros for years.
Regards,
Jim
