Commit 13fca640 authored Jun 15, 2011 by Linus Torvalds

Revert "fs/exec.c: use BUILD_BUG_ON for VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP"



This reverts commit 7f81c889.

It turns out that it's not actually a build-time check on x86-64 UML,
which does some seriously crazy stuff with VM_STACK_FLAGS.

The VM_STACK_FLAGS define depends on the arch-supplied
VM_STACK_DEFAULT_FLAGS value, and on x86-64 UML we have

  arch/um/sys-x86_64/shared/sysdep/vm-flags.h:

	#define VM_STACK_DEFAULT_FLAGS \
		(test_thread_flag(TIF_IA32) ? vm_stack_flags32 : vm_stack_flags)

	#define VM_STACK_DEFAULT_FLAGS vm_stack_flags

(yes, seriously: two different #define's for that thing, with the first
one being inside an "#ifdef TIF_IA32")

It's possible that it is UML that should just be fixed in this area, but
for now let's just undo the (very small) optimization.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 67de0162

fs/exec.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -277,7 +277,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
		* use STACK_TOP because that can depend on attributes which aren't
		* configured yet.
		*/
		BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
		BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
		vma->vm_end = STACK_TOP_MAX;
		vma->vm_start = vma->vm_end - PAGE_SIZE;
		vma->vm_flags = VM_STACK_FLAGS \| VM_STACK_INCOMPLETE_SETUP;

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