On Mon 11-01-21 12:05:49, Jason Gunthorpe wrote: > On Sun, Jan 10, 2021 at 11:26:57PM -0800, John Hubbard wrote: > > > So: > > > > FOLL_PIN: would use DMA_PIN_COUNTING_BIAS to increment page refcount. > > These are long term pins for dma. > > > > FOLL_GET: would use GUP_PIN_COUNTING_BIAS to increment page refcount. > > These are not long term pins. > > Do we have any places yet that care about the long-term-ness? I was hoping to use that information to distinguish ephemeral migration failures due to page reference from long term pins. The later would be a hard failure for the migration. -- Michal Hocko SUSE Labs
