Dear Linux folks,


I enabled the undefined behavior sanitizer, and built Linusa?? master 
branch under Ubuntu 17.10 with gcc (Ubuntu 7.2.0-8ubuntu3) 7.2.0.

```
$ grep UBSAN /boot/config-4.15.0-rc3+
CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y
# CONFIG_ARCH_WANTS_UBSAN_NO_NULL is not set
CONFIG_UBSAN=y
CONFIG_UBSAN_SANITIZE_ALL=y
# CONFIG_UBSAN_ALIGNMENT is not set
CONFIG_UBSAN_NULL=y
```

The warning below is shown when building Linux.

```
$ git describe --tags
v4.15-rc3-37-gd39a01eff9af
$ git log --oneline -1
d39a01eff9af (HEAD -> master, origin/master, origin/HEAD) Merge tag 
'platform-drivers-x86-v4.15-3' of 
git://git.infradead.org/linux-platform-drivers-x86
[a?|]
$ make -j
[a?|]
mm/memcontrol.c: In function a??memory_stat_showa??:
mm/memcontrol.c:5364:1: warning: the frame size of 1032 bytes is larger 
than 1024 bytes [-Wframe-larger-than=]
  }
  ^
[a?|]
```


Kind regards,

Paul