uml: physical memory shouldn't include initial stack

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>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 82058ac7d481950b2a79c5158933ef661383827d..9db85b2ce6987141f314ea0dcc8ddc7f8960cdeb 100644 (file)
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -258,6 +258,7 @@ int __init linux_main(int argc, char **argv)
 {
        unsigned long avail, diff;
        unsigned long virtmem_size, max_physmem;
+       unsigned long stack;
        unsigned int i;
        int add;
        char * mode;
@@ -348,7 +349,9 @@ int __init linux_main(int argc, char **argv)
        }
 
        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;