sparc: Fix kernel BUG at arch/sparc/kernel/mdesc.c

When running ldoms reboot test for long hours, ldom guest panic with
kernel BUG at arch/sparc/kernel/mdesc.c:176! It is because the mdesc
size has changed, mdesc_update should retry the operation by decrement
refcnt before mdesc_free.

orabug 25359044

Signed-off-by: Thomas Tai <thomas.tai@oracle.com>
Reviewed-By: Liam Merwick <Liam.Merwick@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>

diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c
index 603e30f2e6f65395a96724e6ae97060935603340..453eca3afdb9c9b30115dea9b52614d4a3378e82 100644 (file)
--- a/arch/sparc/kernel/mdesc.c
+++ b/arch/sparc/kernel/mdesc.c
@@ -1420,6 +1420,7 @@ void __init sun4v_mdesc_init(void)
 
                status = sun4v_mach_desc(__pa(&hp->mdesc), len, &real_len);
                if (status != HV_EOK || real_len > len) {
+                       atomic_dec(&hp->refcnt);
                        mdesc_free(hp);
                        hp = NULL;
                        continue;