On Wed, Jan 20, 2021 at 8:19 AM Jason Gunthorpe jgg@ziepe.ca wrote:
On Tue, Jan 19, 2021 at 08:43:31PM -0500, Pavel Tatashin wrote:
When pages are longterm pinned, we must migrated them out of movable zone. The function that migrates them has a hidden loop with goto. The loop is to retry on isolation failures, and after successful migration.
Make this code better by moving this loop to the caller.
Signed-off-by: Pavel Tatashin pasha.tatashin@soleen.com mm/gup.c | 88 +++++++++++++++++++++++--------------------------------- 1 file changed, 36 insertions(+), 52 deletions(-)
This looks OK, it is better
Reviewed-by: Jason Gunthorpe jgg@nvidia.com
I really dislike we always have to go over the page list twice in pin mode
I agree, I also dislike that we have to loop twice.
The is_pinnable_page() and LRU isolation should really be done inside __get_user_pages_locked() as each page is added to the output list
But that is more of a larger issue than this series
We could also think about adding some optimization flags, i.e. clients could tell gup that the pinned memory content can be discarded FOLL_DISCARD. That way we could always allocate new pages in the right zones as we do with this series and free existing translations. No migration check would be necessary with such a flag.
Jason