On Wed, Feb 26, 2020 at 09:43:53AM -0800, Yang Shi wrote: > > No. The pagevec_lookup_entries() calls from mm/truncate.c prefer the > > new behavior - evicting the head from page cache removes all the tails > > along with it, so getting the tails a waste of time there too, just as > > it was in shmem_undo_range(). > > TBH I'm not a fun of this hack. This would bring in other confusion or > complexity. Pagevec is supposed to count in the number of base page, now it > would treat THP as one page, and there might be mixed base page and THP in > one pagevec. But, I tend to agree avoiding getting those 14 extra pins at > the first place might be a better approach. All the complexity are used to > release those extra pins. My long-term goal is to eradicate tail pages entirely, so a pagevec will end up containing pages of different sizes. If you want to help move in this direction, I'd be awfully grateful. But I wouldn't say that's in any way a prerequisite for fixing this current problem.
