mm: support MADV_FREE on swapless system
Historically, we have disabled reclaiming of anonymous pages
completely with swapoff or non-swap configurable system.
It did make sense but problem for lazy free pages is that
we couldn't get a chance to discard MADV_FREE hinted pages
in reclaim path in those systems.
That's why current MADV_FREE implementation drops pages instantly
like MADV_DONTNNED in swapless system so that users on those
systems couldn't get the benefit of MADV_FREE.
Now we have lazyfree LRU list to keep MADV_FREEed pages without
relying on anonymous LRU so that we could scan MADV_FREE pages
on swapless system without relying on anonymous LRU list.
Signed-off-by: Minchan Kim <minchan@kernel.org>
3 files changed
