Booting with kernel parameter "rdt=cmt,mbmtotal,memlocal,l3cat,mba" and
executing "mount -t resctrl resctrl -o mba_MBps /sys/fs/resctrl"
results in a panic on systems without local MBM support enabled in
firmware.
BUG: kernel NULL pointer dereference, address: 0000000000000020
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 722 Comm: kworker/0:3 Not tainted
5.2.0-0.rc3.git0.1.el7_UNSUPPORTED.x86_64 #2
Hardware name: Dell Inc. PowerEdge R740/0923K0, BIOS 2.1.8 04/30/2019
Workqueue: events mbm_handle_overflow
RIP: 0010:mbm_handle_overflow+0x150/0x2b0
Only call the bandwith update loop if the system has local MBM enabled.
Signed-off-by: Prarit Bhargava <pra...@redhat.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: Reinette Chatre <reinette.cha...@intel.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: x...@kernel.org
---
arch/x86/kernel/cpu/resctrl/monitor.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
b/arch/x86/kernel/cpu/resctrl/monitor.c
index 7ee93125a211..397206f23d14 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -360,6 +360,9 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct
rdt_domain *dom_mbm)
struct list_head *head;
struct rdtgroup *entry;
+ if (!is_mbm_local_enabled())
+ return;
+
r_mba = &rdt_resources_all[RDT_RESOURCE_MBA];
closid = rgrp->closid;
rmid = rgrp->mon.rmid;
--
2.21.0
