Re: [PATCH v3 2/3] mm/migrate_device.c: Copy pte dirty bit to page

[Peter Xu]

On Fri, Aug 26, 2022 at 04:47:22PM +0200, David Hildenbrand wrote:
> > To me anon exclusive only shows this mm exclusively owns this page. I
> > didn't quickly figure out why that requires different handling on tlb
> > flushs.  Did I perhaps miss something?
> 
> GUP-fast is the magic bit, we have to make sure that we won't see new
> GUP pins, thus the TLB flush.
> 
> include/linux/mm.h:gup_must_unshare() contains documentation.

Hmm.. Shouldn't ptep_get_and_clear() (e.g., xchg() on x86_64) already
guarantees that no other process/thread will see this pte anymore
afterwards?

-- 
Peter Xu