From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46522 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935376AbdCVQko (ORCPT ); Wed, 22 Mar 2017 12:40:44 -0400 Subject: Patch "Drivers: hv: avoid vfree() on crash" has been added to the 4.4-stable tree To: vkuznets@redhat.com, gregkh@linuxfoundation.org, kys@microsoft.com, sumit.semwal@linaro.org Cc: , From: Date: Wed, 22 Mar 2017 17:38:55 +0100 Message-ID: <149020073585108@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled Drivers: hv: avoid vfree() on crash to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drivers-hv-avoid-vfree-on-crash.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From a9f61ca793becabdefab03b77568d6c6f8c1bc79 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 3 Jun 2016 17:09:22 -0700 Subject: Drivers: hv: avoid vfree() on crash From: Vitaly Kuznetsov 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. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Cc: Sumit Semwal Signed-off-by: Greg Kroah-Hartman --- drivers/hv/hv.c | 8 +++++--- drivers/hv/hyperv_vmbus.h | 2 +- drivers/hv/vmbus_drv.c | 8 ++++---- 3 files changed, 10 insertions(+), 8 deletions(-) --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -274,7 +274,7 @@ 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; @@ -284,7 +284,8 @@ 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; } @@ -304,7 +305,8 @@ 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 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -581,7 +581,7 @@ 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, --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -889,7 +889,7 @@ err_alloc: bus_unregister(&hv_bus); err_cleanup: - hv_cleanup(); + hv_cleanup(false); return ret; } @@ -1254,7 +1254,7 @@ static void hv_kexec_handler(void) vmbus_initiate_unload(); 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) @@ -1266,7 +1266,7 @@ static void hv_crash_handler(struct pt_r * for kdump. */ hv_synic_cleanup(NULL); - hv_cleanup(); + hv_cleanup(true); }; static int __init hv_acpi_init(void) @@ -1330,7 +1330,7 @@ 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); Patches currently in stable-queue which might be from vkuznets@redhat.com are queue-4.4/drivers-hv-balloon-don-t-crash-when-memory-is-added-in-non-sorted-order.patch queue-4.4/drivers-hv-avoid-vfree-on-crash.patch queue-4.4/hv_netvsc-use-skb_get_hash-instead-of-a-homegrown-implementation.patch