Comment 16 for bug 1677611

FWIW, I cherry-picked these commits:

093b995e3b55 mm, swap: Remove WARN_ON_ONCE() in free_swap_slot()
452b94b8c8c7 mm/swap: don't BUG_ON() due to uninitialized swap slot cache
ba81f8384254 mm/swap: skip readahead only when swap slot cache is enabled
039939a65059 mm/swap: enable swap slots cache usage
67afa38e012e mm/swap: add cache for swap slots allocation
7c00bafee87c mm/swap: free swap slots in batch
36005bae205d mm/swap: allocate swap slots in batches
e8c26ab60598 mm/swap: skip readahead for unreferenced swap slots
4b3ef9daa4fc mm/swap: split swap cache into 64MB trunks
235b62176712 mm/swap: add cluster lock
6a991fc72d12 mm/swap: fix kernel message in swap_info_get()

But apparently it did not work...