From: Gaurav Kohli gauravkohli@linux.microsoft.com
[ Upstream commit 32c97d980e2eef25465d453f2956a9ca68926a3c ]
Hyper-V cleanup code comes under panic path where preemption and irq is already disabled. So calling of unregister_syscore_ops might schedule out the thread even for the case where mutex lock is free. hyperv_cleanup unregister_syscore_ops mutex_lock(&syscore_ops_lock) might_sleep Here might_sleep might schedule out this thread, where voluntary preemption config is on and this thread will never comes back. And also this was added earlier to maintain the symmetry which is not required as this can comes during crash shutdown path only.
To prevent the same, removing unregister_syscore_ops function call.
Signed-off-by: Gaurav Kohli gauravkohli@linux.microsoft.com Reviewed-by: Michael Kelley mikelley@microsoft.com Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@linux... Signed-off-by: Wei Liu wei.liu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/hyperv/hv_init.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index a269049a43ce..85863b9c9e68 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -535,8 +535,6 @@ void hyperv_cleanup(void) union hv_x64_msr_hypercall_contents hypercall_msr; union hv_reference_tsc_msr tsc_msr;
- unregister_syscore_ops(&hv_syscore_ops); - /* Reset our OS id */ wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0); hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);