This is a note to let you know that I've just added the patch titled
x86/hyperv: Remove unregister syscore call from Hyper-V cleanup
to the 6.0-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:
x86-hyperv-remove-unregister-syscore-call-from-hyper.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4c3298611582de925329c7f971efae9f957d2fa6
Author: Gaurav Kohli <gauravkohli@xxxxxxxxxxxxxxxxxxx>
Date: Fri Nov 25 22:14:51 2022 -0800
x86/hyperv: Remove unregister syscore call from Hyper-V cleanup
[ 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@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/1669443291-2575-1-git-send-email-gauravkohli@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index a0165df3c4d8..d03561b2fffe 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -536,8 +536,6 @@ void hyperv_cleanup(void)
{
union hv_x64_msr_hypercall_contents hypercall_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);
