[PATCH sched_ext/for-7.3] sched_ext: Make SCHED_CLASS_EXT select GENERIC_ALLOCATOR

[Tejun Heo <tj@kernel.org>]

kernel/sched/ext/arena.c uses the gen_pool allocator, which is built only
when GENERIC_ALLOCATOR is set. SCHED_CLASS_EXT doesn't select it, so on
configs where nothing else does, the build fails to link:

  build_policy.o: undefined reference to `gen_pool_create'
  build_policy.o: undefined reference to `gen_pool_for_each_chunk'
  build_policy.o: undefined reference to `gen_pool_destroy'

Fixes: 9eca087deb0b ("sched_ext: Sub-allocator over kernel-claimed BPF arena pages")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202608151315.tvN3X0Oq-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202608151632.3p91bTQj-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/Kconfig.preempt |    1 +
 1 file changed, 1 insertion(+)

--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -169,6 +169,7 @@ config SCHED_CORE
 config SCHED_CLASS_EXT
 	bool "Extensible Scheduling Class"
 	depends on BPF_SYSCALL && BPF_JIT && DEBUG_INFO_BTF
+	select GENERIC_ALLOCATOR
 	select STACKTRACE if STACKTRACE_SUPPORT
 	help
 	  This option enables a new scheduler class sched_ext (SCX), which