Revert "mm: frontswap: core frontswap functionality"

This reverts commit dd20539553224dbd5d3ff40b733d33b5f3601bec.
Revert "mm/zbud: fix some trivial typos in comments"

This reverts commit 48e78a2ca9df484db22fab39bc83a20cbe454420.
Revert "mm: zbud: fix condition check on allocation size"

This reverts commit 4e01c9f3e2ff3bf63c1027fecd14e8f5b35426ea.
Revert "mm/zswap: bugfix: memory leak when re-swapon"

This reverts commit 03fe88a3289f177acc683d9bfac852b0c2e54489.
Revert "mm/zswap: use postorder iteration when destroying rbtree"

This reverts commit 58e0123f845bebb32787846d9f7f6d419e3f2286.
Revert "mm/zswap.c: get swapper address_space by using macro"

This reverts commit 0383cdfa72a87fab2f362ec19102697acd0506ea.
Revert "zswap: fix Kconfig to depend on CRYPTO=y"

This reverts commit ac0de8c394205d2c378a9c000533c5f524b766e2.
Revert "zswap: add to mm/"

This reverts commit c82f418b571d38710a2b1f6fa75e9ed499527e30.
Revert "zbud: add to mm/"

This reverts commit bdff74985edca45bd3f13d8c802d7417d028b703.