Drivers: hv: avoid vfree() on crash

commit a9f61ca793becabdefab03b77568d6c6f8c1bc79 upstream.

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.

[js] no tsc and kexec in 3.12 yet

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index 9c0d458ec2329105222fb238783c6946a392606a..24d3ceec9d0a923a4fb1ae8431da9d90082bfc83 100644 (file)
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -193,7 +193,7 @@ cleanup:
  *
  * 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;
 
@@ -203,7 +203,8 @@ void hv_cleanup(void)
        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;
        }
 }

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index d84918fe19ab7023e4189b0cb52d98495340abd1..862004c15c41a3a37d50bfd0209539f6aa5ef0f8 100644 (file)
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -519,7 +519,7 @@ extern struct hv_context hv_context;
 
 extern int hv_init(void);
 
-extern void hv_cleanup(void);
+extern void hv_cleanup(bool crash);
 
 extern int hv_post_message(union hv_connection_id connection_id,
                         enum hv_message_type message_type,

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index d13f3dda676956986359b232296ac7526532436d..37f697fcf4773da33a6391ad675ad50ff10d5540 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -622,7 +622,7 @@ err_unregister:
        bus_unregister(&hv_bus);
 
 err_cleanup:
-       hv_cleanup();
+       hv_cleanup(false);
 
        return ret;
 }
@@ -845,7 +845,7 @@ static void __exit vmbus_exit(void)
        free_irq(irq, hv_acpi_dev);
        vmbus_free_channels();
        bus_unregister(&hv_bus);
-       hv_cleanup();
+       hv_cleanup(false);
        acpi_bus_unregister_driver(&vmbus_acpi_driver);
        hv_cpu_hotplug_quirk(false);
 }