enable a bunch of mm options

- zswap on by default with lz4 and zsmalloc
- KSM
- deferred struct page init
- idle page tracking

Also switched CRYPTO_ZSTD to built-in.

kernel/build/config-amd64

@@ -1025,9 +1025,28 @@ CONFIG_COREDUMP=y
 #
 # Memory Management options
 #
+CONFIG_ZPOOL=y
 CONFIG_SWAP=y
-# CONFIG_ZSWAP is not set
+CONFIG_ZSWAP=y
+CONFIG_ZSWAP_DEFAULT_ON=y
+CONFIG_ZSWAP_SHRINKER_DEFAULT_ON=y
+# CONFIG_ZSWAP_COMPRESSOR_DEFAULT_DEFLATE is not set
+# CONFIG_ZSWAP_COMPRESSOR_DEFAULT_LZO is not set
+# CONFIG_ZSWAP_COMPRESSOR_DEFAULT_842 is not set
+CONFIG_ZSWAP_COMPRESSOR_DEFAULT_LZ4=y
+# CONFIG_ZSWAP_COMPRESSOR_DEFAULT_LZ4HC is not set
+# CONFIG_ZSWAP_COMPRESSOR_DEFAULT_ZSTD is not set
+CONFIG_ZSWAP_COMPRESSOR_DEFAULT="lz4"
+# CONFIG_ZSWAP_ZPOOL_DEFAULT_ZBUD is not set
+# CONFIG_ZSWAP_ZPOOL_DEFAULT_Z3FOLD is not set
+CONFIG_ZSWAP_ZPOOL_DEFAULT_ZSMALLOC=y
+CONFIG_ZSWAP_ZPOOL_DEFAULT="zsmalloc"
+# CONFIG_ZBUD is not set
+# CONFIG_Z3FOLD is not set
 CONFIG_HAVE_ZSMALLOC=y
+CONFIG_ZSMALLOC=y
+# CONFIG_ZSMALLOC_STAT is not set
+CONFIG_ZSMALLOC_CHAIN_SIZE=8
 
 #
 # Slab allocator options
@@ -1078,7 +1097,7 @@ CONFIG_CONTIG_ALLOC=y
 CONFIG_PCP_BATCH_SCALE_MAX=5
 CONFIG_PHYS_ADDR_T_64BIT=y
 CONFIG_MMU_NOTIFIER=y
-# CONFIG_KSM is not set
+CONFIG_KSM=y
 CONFIG_DEFAULT_MMAP_MIN_ADDR=65536
 CONFIG_ARCH_SUPPORTS_MEMORY_FAILURE=y
 CONFIG_MEMORY_FAILURE=y
@@ -1098,8 +1117,9 @@ CONFIG_USE_PERCPU_NUMA_NODE_ID=y
 CONFIG_HAVE_SETUP_PER_CPU_AREA=y
 # CONFIG_CMA is not set
 CONFIG_GENERIC_EARLY_IOREMAP=y
-# CONFIG_DEFERRED_STRUCT_PAGE_INIT is not set
-# CONFIG_IDLE_PAGE_TRACKING is not set
+CONFIG_DEFERRED_STRUCT_PAGE_INIT=y
+CONFIG_PAGE_IDLE_FLAG=y
+CONFIG_IDLE_PAGE_TRACKING=y
 CONFIG_ARCH_HAS_CACHE_LINE_SIZE=y
 CONFIG_ARCH_HAS_CURRENT_STACK_POINTER=y
 CONFIG_ARCH_HAS_PTE_DEVMAP=y
@@ -5080,9 +5100,9 @@ CONFIG_CRYPTO_CRC64_ROCKSOFT=y
 CONFIG_CRYPTO_DEFLATE=y
 CONFIG_CRYPTO_LZO=y
 # CONFIG_CRYPTO_842 is not set
-# CONFIG_CRYPTO_LZ4 is not set
+CONFIG_CRYPTO_LZ4=y
 # CONFIG_CRYPTO_LZ4HC is not set
-CONFIG_CRYPTO_ZSTD=m
+CONFIG_CRYPTO_ZSTD=y
 # end of Compression
 
 #
@@ -5268,6 +5288,7 @@ CONFIG_ZLIB_INFLATE=y
 CONFIG_ZLIB_DEFLATE=y
 CONFIG_LZO_COMPRESS=y
 CONFIG_LZO_DECOMPRESS=y
+CONFIG_LZ4_COMPRESS=y
 CONFIG_LZ4_DECOMPRESS=y
 CONFIG_ZSTD_COMMON=y
 CONFIG_ZSTD_COMPRESS=y