Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754373AbdDJQBl (ORCPT ); Mon, 10 Apr 2017 12:01:41 -0400 Received: from mx2.suse.de ([195.135.220.15]:38054 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754308AbdDJPeU (ORCPT ); Mon, 10 Apr 2017 11:34:20 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Vitaly Kuznetsov , "K . Y . Srinivasan" , Sumit Semwal , Jiri Slaby Subject: [PATCH 3.12 048/142] Drivers: hv: avoid vfree() on crash Date: Mon, 10 Apr 2017 17:32:09 +0200 Message-Id: X-Mailer: git-send-email 2.12.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2652 Lines: 90 From: Vitaly Kuznetsov 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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 --- 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 9c0d458ec232..24d3ceec9d0a 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 d84918fe19ab..862004c15c41 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 d13f3dda6769..37f697fcf477 100644 --- 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); } -- 2.12.2