From 9391c802ff00fc5873e91ce26dd08c9f4e2a8e92 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 3 Jun 2016 17:09:22 -0700 Subject: [PATCH] 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 Signed-off-by: K. Y. Srinivasan Cc: Sumit Semwal Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- drivers/hv/hv.c | 5 +++-- drivers/hv/hyperv_vmbus.h | 2 +- drivers/hv/vmbus_drv.c | 4 ++-- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index ae4923756d98..b1039552b623 100644 --- 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 12f2f9e989f7..11d4e6222f52 100644 --- 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 80754e2d8086..3190a1fc7bc8 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -618,7 +618,7 @@ err_unregister: bus_unregister(&hv_bus); err_cleanup: - hv_cleanup(); + hv_cleanup(false); return ret; } @@ -841,7 +841,7 @@ 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); } -- 2.20.1