From: Thomas Tai <thomas.tai@oracle.com>
Date: Fri, 6 Jan 2017 14:18:38 +0000 (-0800)
Subject: sparc: Fix kernel BUG at arch/sparc/kernel/mdesc.c
X-Git-Tag: v4.1.12-104.0.20170618_1145~238
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=f54035fbff7a416cd4ab45a22e351694d3c001ed;p=users%2Fjedix%2Flinux-maple.git

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 603e30f2e6f65..453eca3afdb9c 100644
--- 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;