On 10/04/2017 09:05 AM, Christopher Lameter wrote: > On Wed, 4 Oct 2017, Anshuman Khandual wrote: > >>> - Using 'pre-allocated' pages in the fault paths may be intrusive. >> >> But we have already faulted in all of them for the mapping and they >> are also locked. Hence there should not be any page faults any more >> for the VMA. Am I missing something here ? > > The PTEs may be torn down and have to reestablished through a page faults. > Page faults would not allocate memory. > >> I am still wondering why wait till fault time not pre fault all of them >> and populate the page tables. > > They are populated but some processes (swap and migration) may tear them > down.
As mentioned in my reply to Anshuman, the mention of fault paths here may be a source of confusion. I would expect the entire mapping to be populated at mmap time, and the pages locked. Therefore, there should be no swap or migration. -- Mike Kravetz
