* Christian Borntraeger [off-list ref] wrote:

quoted

By all means!

You'll first need to cherry-pick these commits:

quoted

 927609d622a3 kernel: tighten rules for ACCESS ONCE
 c5b19946eb76 kernel: Fix sparse warning for ACCESS_ONCE
 dd36929720f4 kernel: make READ_ONCE() valid on const arguments

If you go before 3.19, you will also need

   230fa253df63 kernel: Provide READ_ONCE and ASSIGN_ONCE
   43239cbe79fc kernel: Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val)

The affected spinlock code went over several iterations 
post v3.18, which I think makes the spinlock change too 
risky and complex to backport so far back. So it's not 
necessay to backport these READ_ONCE() changes.

quoted

That's the minimum set you will need for backporting, 
due to overlapping changes to the ACCESS_ONCE() 
definition.

and then apply this commit:

 d6abfdb20223 x86/spinlocks/paravirt: Fix memory corruption on unlock

the alternative might be to replace READ_ONCE with 
ACCESS_ONCE when doing the backport.

Doing changes to patches when doing a backport is a big 
no-no IMHO. Either there is a clean sequence of upstream 
commit IDs to cherry-pick, or it should not be backported 
in most cases.

Thanks,

	Ingo