PAGE_EXEC is required for inittext, otherwise CONFIG_DEBUG_PAGEALLOC
ends up with an Oops

[    0.000000] Inode-cache hash table entries: 8192 (order: 1, 32768 bytes)
[    0.000000] Sorting __ex_table...
[    0.000000] bootmem::free_all_bootmem_core nid=0 start=0 end=2000
[    0.000000] Unable to handle kernel paging request for instruction fetch
[    0.000000] Faulting instruction address: 0xc045b970
[    0.000000] Oops: Kernel access of bad area, sig: 11 [#1]
[    0.000000] PREEMPT DEBUG_PAGEALLOC CMPC885
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.18.25-local-dirty #1673
[    0.000000] task: c04d83d0 ti: c04f8000 task.ti: c04f8000
[    0.000000] NIP: c045b970 LR: c045b970 CTR: 0000000a
[    0.000000] REGS: c04f9ea0 TRAP: 0400   Not tainted  (3.18.25-local-dirty)
[    0.000000] MSR: 08001032 <ME,IR,DR,RI>  CR: 39955d35  XER: a000ff40
[    0.000000]
GPR00: c045b970 c04f9f50 c04d83d0 00000000 ffffffff c04dcdf4 00000048 c04f6b10
GPR08: c04f6ab0 00000001 c0563488 c04f6ab0 c04f8000 00000000 00000000 b6db6db7
GPR16: 00003474 00000180 00002000 c7fec000 00000000 000003ff 00000176 c0415014
GPR24: c0471018 c0414ee8 c05304e8 c03aeaac c0510000 c0471018 c0471010 00000000
[    0.000000] NIP [c045b970] free_all_bootmem+0x164/0x228
[    0.000000] LR [c045b970] free_all_bootmem+0x164/0x228
[    0.000000] Call Trace:
[    0.000000] [c04f9f50] [c045b970] free_all_bootmem+0x164/0x228 (unreliable)
[    0.000000] [c04f9fa0] [c0454044] mem_init+0x3c/0xd0
[    0.000000] [c04f9fb0] [c045080c] start_kernel+0x1f4/0x390
[    0.000000] [c04f9ff0] [c0002214] start_here+0x38/0x98
[    0.000000] Instruction dump:
[    0.000000] 2f150000 7f968840 72a90001 3ad60001 56b5f87e 419a0028 419e0024 41a20018
[    0.000000] 807cc20c 38800000 7c638214 4bffd2f5 <3a940001> 3a100024 4bffffc8 7e368b78
[    0.000000] ---[ end trace dc8fa200cb88537f ]---
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>