On 5/21/21 9:33 PM, Linus Torvalds wrote:

On Fri, May 21, 2021 at 3:04 AM Aneesh Kumar K.V
[off-list ref] wrote:

quoted

We could do MOVE_PMD with something like below? A equivalent MOVE_PUD
will be costlier which makes me wonder whether we should even support that?

Well, without USE_SPLIT_PTE_PTLOCKS the pud case would be trivial too.
But everybody uses split pte locks in practice.

Ok I can get a patch series enabling MOVE_PUD only with 
SPLIT_PTE_PTLOCKS disabled.

I get the feeling that the rmap code might have to use
pud_lock/pmd_lock. I wonder how painful that would be.

and work long term on that? The lock/unlocking can get complicated 
because the page_vma_walk now need to return all the held locks.


-aneesh