Re: [PATCH] xen: fix usage of pmd/pud_poplulate in mremap for pv guests

From: Jan Beulich
Date: Wed Sep 08 2021 - 10:28:24 EST

On 08.09.2021 15:32, Juergen Gross wrote:
> On 08.09.21 13:07, Jan Beulich wrote:
>> On 08.09.2021 09:36, Juergen Gross wrote:
>>> Commit 0881ace292b662 ("mm/mremap: use pmd/pud_poplulate to update page
>>> table entries") introduced a regression when running as Xen PV guest.
>> The description of that change starts with "pmd/pud_populate is the
>> right interface to be used to set the respective page table entries."
>> If this is deemed true, I don't think pmd_populate() should call
>> paravirt_alloc_pte(): The latter function, as its name says, is
>> supposed to be called for newly allocated page tables only (aiui).
> In theory you are correct, but my experience with reality tells me that
> another set of macros for this case will not be appreciated.

Perhaps a new parameter to the macros / inlines identifying fresh
vs moved? Or perhaps the offending change wasn't really correct in
what its description said?