Add generic exit-time stack-depth checking to CONFIG_DEBUG_STACK_USAGE. This also adds UML support. Tested on UML and i386. [akpm@linux-foundation.org: cleanups, speedups, tweaks] Signed-off-by: Jeff Dike <jdike@linux.intel.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>