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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>
This commit is contained in:
Vitaly Kuznetsov 2016-06-03 17:09:22 -07:00 committed by Greg Kroah-Hartman
parent 069b188f43
commit a9f61ca793
3 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/hv/hv.c
View File

@ -278,7 +278,7 @@ int hv_init(void)
*
* 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

2
drivers/hv/hyperv_vmbus.h
View File

@ -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,

8
drivers/hv/vmbus_drv.c
View File

@ -874,7 +874,7 @@ static int vmbus_bus_init(void)
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);