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Pavel Tatashin
e44605a8b1
When pages are pinned they can be faulted in userland and migrated, and they can be faulted right in kernel without migration. In either case, the pinned pages must end-up being pinnable (not movable). Add a new test to gup_test, to help verify that the gup/pup (get_user_pages() / pin_user_pages()) behavior with respect to pinnable and movable pages is reasonable and correct. Specifically, provide a way to: 1) Verify that only "pinnable" pages are pinned. This is checked automatically for you. 2) Verify that gup/pup performance is reasonable. This requires comparing benchmarks between doing gup/pup on pages that have been pre-faulted in from user space, vs. doing gup/pup on pages that are not faulted in until gup/pup time (via FOLL_TOUCH). This decision is controlled with the new -z command line option. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Pavel Tatashin <[email protected]> Reviewed-by: John Hubbard <[email protected]> Cc: Dan Williams <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: David Rientjes <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Ira Weiny <[email protected]> Cc: James Morris <[email protected]> Cc: Jason Gunthorpe <[email protected]> Cc: Jason Gunthorpe <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sasha Levin <[email protected]> Cc: Steven Rostedt (VMware) <[email protected]> Cc: Tyler Hicks <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>