On 10/24/2016 10:38 AM, Dave Hansen wrote: > On 10/23/2016 09:31 PM, Anshuman Khandual wrote: >> > VMAs containing coherent device memory should be marked with VM_CDM. These >> > VMAs need to be identified in various core kernel paths and this new flag >> > will help in this regard. > ... and it's sticky? So if a VMA *ever* has one of these funky pages in > it, it's stuck being VM_CDM forever? Never to be merged with other > VMAs? Never to see the light of autonuma ever again?
Urg, this is even worse than I suspected. Does this handle shared pages (like the page cache mode you call out as a requirement) where the "cdm" page is faulted into one process VMA, but it was allocated against another? Can't that give you a "cdm" page mapped into a non-VM_CDM VMA? Or, a VM_CDM VMA with no "cdm" pages in it?
