Drivers: hv: avoid vfree() on crash
When we crash from NMI context (e.g. after NMI injection from host when
'sysctl -w kernel.unknown_nmi_panic=1' is set) we hit
kernel BUG at mm/vmalloc.c:1530!
as vfree() is denied. While the issue could be solved with in_nmi() check
instead I opted for skipping vfree on all sorts of crashes to reduce the
amount of work which can cause consequent crashes. We don't really need to
free anything on crash.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index a1c086b..60dbd6c 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -278,7 +278,7 @@
*
* This routine is called normally during driver unloading or exiting.
*/
-void hv_cleanup(void)
+void hv_cleanup(bool crash)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
@@ -288,7 +288,8 @@
if (hv_context.hypercall_page) {
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
- vfree(hv_context.hypercall_page);
+ if (!crash)
+ vfree(hv_context.hypercall_page);
hv_context.hypercall_page = NULL;
}
@@ -308,7 +309,8 @@
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
- vfree(hv_context.tsc_page);
+ if (!crash)
+ vfree(hv_context.tsc_page);
hv_context.tsc_page = NULL;
}
#endif