kernel: fix missing TRANSPARENT_HUGEPAGE symbols

Enabling KERNEL_TRANSPARENT_HUGEPAGE exposes 2 missing symbols:
* CONFIG_READ_ONLY_THP_FOR_FS
* TRANSPARENT_HUGEPAGE_ALWAYS
* TRANSPARENT_HUGEPAGE_MADVISE

The first one was added in 5.4, and is marked experimental there so just
disable it in the generic config.

For the latter two, we should not force the user to use either of them,
so add them as build-configurable kernel options.

Fixes: d1a8217d87bf ("kernel: clean-up build-configurable kernel config symbols")
Signed-off-by: Stijn Tintel <[email protected]>

config/Config-kernel.in

@@ -360,6 +360,18 @@ config KERNEL_BLK_DEV_BSG
 config KERNEL_TRANSPARENT_HUGEPAGE
 	bool
 
+choice
+	prompt "Transparent Hugepage Support sysfs defaults"
+	depends on KERNEL_TRANSPARENT_HUGEPAGE
+	default KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
+
+	config KERNEL_TRANSPARENT_HUGEPAGE_ALWAYS
+		bool "always"
+
+	config KERNEL_TRANSPARENT_HUGEPAGE_MADVISE
+		bool "madvise"
+endchoice
+
 config KERNEL_HUGETLBFS
 	bool
 

target/linux/generic/config-5.4

@@ -4211,6 +4211,7 @@ CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY=3
 # CONFIG_RD_LZO is not set
 # CONFIG_RD_XZ is not set
 # CONFIG_READABLE_ASM is not set
+# CONFIG_READ_ONLY_THP_FOR_FS is not set
 # CONFIG_REALTEK_PHY is not set
 # CONFIG_REDWOOD is not set
 # CONFIG_REED_SOLOMON_TEST is not set