On 28.07.22 10:45, Alistair Popple wrote: > > Looks like the original patch might need rebasing. I am about to post a > clean-up for the tortured logic in check_and_migrate_movable_pages() so > can incorporate it there, but I'm wondering what the consensus was for > pinning of zero pfn? We have to keep it working right now, but in most cases (inside MAP_PRIVATE regions) it's shaky and undesired. > > Currently my clean-up will result in PUP returning an error for the zero > pfn rather than looping indefinitely in the kernel. However it wasn't > clear from this thread if returning an error is ok, or if R/O pinning > of the zero pfn should succeed? I'm working on proper COW breaking in MAP_PRIVATE mappings, which will, for example, unshare the shared zeropage and properly replace it by exclusive anon pages first in the FOLL_LONGTERM case. -- Thanks, David / dhildenb
