hmm pud-entry callback locking?

[Thomas HellstrÃm (VMware)]

Hi, Jerome,

I was asked by Kirill to try to unify the pagewalk pud_entry and 
pmd_entry callbacks. The only user of the pagewalk pud-entry is 
currently hmm.

But the pagewalk code call pud_entry only for huge puds with the 
page-table lock held, whereas the hmm callback appears to assume it gets 
called unconditionally without the page-table lock held?

Could you shed some light into this?

Thanks,
Thomas