The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 56ef6718a1d8d77745033c5291e025ce18504159 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Date: Wed, 7 Dec 2016 01:16:27 -0800 Subject: [PATCH] hv: don't reset hv_context.tsc_page on crash It may happen that secondary CPUs are still alive and resetting hv_context.tsc_page will cause a consequent crash in read_hv_clock_tsc() as we don't check for it being not NULL there. It is safe as we're not freeing this page anyways. Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c index 13937563c9db..fbd8ce6d7ff3 100644 --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -309,9 +309,10 @@ void hv_cleanup(bool crash) hypercall_msr.as_uint64 = 0; wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); - if (!crash) + if (!crash) { vfree(hv_context.tsc_page); - hv_context.tsc_page = NULL; + hv_context.tsc_page = NULL; + } } #endif }