Commit a9f61ca7 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
Browse files

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: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 069b188f

drivers/hv/hv.c

+5 −3
Original line number Diff line number Diff line
@@ -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;
@@ -288,6 +288,7 @@ void hv_cleanup(void) 
	if (hv_context.hypercall_page) {

		hypercall_msr.as_uint64 = 0;

		wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

		if (!crash)

			vfree(hv_context.hypercall_page);

		hv_context.hypercall_page = NULL;

	}
@@ -308,6 +309,7 @@ void hv_cleanup(void) 


		hypercall_msr.as_uint64 = 0;

		wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);

		if (!crash)

			vfree(hv_context.tsc_page);

		hv_context.tsc_page = NULL;

	}

drivers/hv/hyperv_vmbus.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

drivers/hv/vmbus_drv.c

+4 −4
Original line number Diff line number Diff line
@@ -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);

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