[PATCH 19/19] UML - Physical memory shouldn't include initial stack

[PATCH 19/19] UML - Physical memory shouldn't include initial stack

[Jeff Dike]

The top of physical memory should be below the initial process stack,
not the top of the address space, at least for as long as the stack
isn't known to the kernel VM system and appropriately reserved.

Cc: "Christopher S. Aker" <caker@theshore.net>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
---
 arch/um/kernel/um_arch.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Index: linux-2.6-git/arch/um/kernel/um_arch.c
===================================================================
--- linux-2.6-git.orig/arch/um/kernel/um_arch.c	2008-04-24 15:16:52.000000000 -0400
+++ linux-2.6-git/arch/um/kernel/um_arch.c	2008-04-24 16:04:52.000000000 -0400
@@ -258,6 +258,7 @@ int __init linux_main(int argc, char **a
 {
 	unsigned long avail, diff;
 	unsigned long virtmem_size, max_physmem;
+	unsigned long stack;
 	unsigned int i, add;
 	char * mode;
 
@@ -347,7 +348,9 @@ int __init linux_main(int argc, char **a
 	}
 
 	virtmem_size = physmem_size;
-	avail = TASK_SIZE - start_vm;
+	stack = (unsigned long) argv;
+	stack &= ~(1024 * 1024 - 1);
+	avail = stack - start_vm;
 	if (physmem_size > avail)
 		virtmem_size = avail;
 	end_vm = start_vm + virtmem_size;