Currently, when all modules, including VMCI and VMware balloon are built into the kernel, the initialization of the balloon happens before the VMCI is probed. As a result, the balloon fails to initialize the VMCI doorbell, which it uses to get asynchronous requests for balloon size changes.
The problem can be seen in the logs, in the form of the following message: "vmw_balloon: failed to initialize vmci doorbell"
The driver would work correctly but slightly less efficiently, probing for requests periodically. This patch changes the balloon to be initialized using late_initcall() instead of module_init() to address this issue. It does not address a situation in which VMCI is built as a module and the balloon is built into the kernel.
Fixes: 48e3d668b790 ("VMware balloon: Enable notification via VMCI") Cc: stable@vger.kernel.org Reviewed-by: Xavier Deguillard xdeguillard@vmware.com Signed-off-by: Nadav Amit namit@vmware.com --- drivers/misc/vmw_balloon.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c index a7df4c24a28d..e7cfc85f6961 100644 --- a/drivers/misc/vmw_balloon.c +++ b/drivers/misc/vmw_balloon.c @@ -1297,7 +1297,14 @@ static int __init vmballoon_init(void)
return 0; } -module_init(vmballoon_init); + +/* + * Using late_initcall() instead of module_init() allows the balloon to use the + * VMCI doorbell even when the balloon is built into the kernel. Otherwise the + * VMCI is probed only after the balloon is initialized. If the balloon is used + * as a module, late_initcall() is equivalent to module_init(). + */ +late_initcall(vmballoon_init);
static void __exit vmballoon_exit(void) {