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authorVitaly Kuznetsov <vkuznets@redhat.com>2016-06-04 00:09:22 (GMT)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-08-31 11:05:40 (GMT)
commita9f61ca793becabdefab03b77568d6c6f8c1bc79 (patch)
tree422f0e2eb47880341e6ebe69a1afa918458c4dd4
parent069b188f43d9a44422eb35a8f95533d2c44ad315 (diff)
downloadlinux-a9f61ca793becabdefab03b77568d6c6f8c1bc79.tar.xz
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>
-rw-r--r--drivers/hv/hv.c8
-rw-r--r--drivers/hv/hyperv_vmbus.h2
-rw-r--r--drivers/hv/vmbus_drv.c8
3 files changed, 10 insertions, 8 deletions
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 @@ 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;
@@ -288,7 +288,8 @@ 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;
}
@@ -308,7 +309,8 @@ void hv_cleanup(void)
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
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 718b5c7..dfa9fac 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -495,7 +495,7 @@ struct hv_ring_buffer_debug_info {
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 e82f7e1..fedf629 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -874,7 +874,7 @@ err_alloc:
bus_unregister(&hv_bus);
err_cleanup:
- hv_cleanup();
+ hv_cleanup(false);
return ret;
}
@@ -1326,7 +1326,7 @@ static void hv_kexec_handler(void)
vmbus_initiate_unload(false);
for_each_online_cpu(cpu)
smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);
- hv_cleanup();
+ hv_cleanup(false);
};
static void hv_crash_handler(struct pt_regs *regs)
@@ -1338,7 +1338,7 @@ static void hv_crash_handler(struct pt_regs *regs)
* for kdump.
*/
hv_synic_cleanup(NULL);
- hv_cleanup();
+ hv_cleanup(true);
};
static int __init hv_acpi_init(void)
@@ -1398,7 +1398,7 @@ static void __exit vmbus_exit(void)
&hyperv_panic_block);
}
bus_unregister(&hv_bus);
- hv_cleanup();
+ hv_cleanup(false);
for_each_online_cpu(cpu) {
tasklet_kill(hv_context.event_dpc[cpu]);
smp_call_function_single(cpu, hv_synic_cleanup, NULL, 1);