uml: physical memory shouldn't include initial stack

commit 60a2988aea701a6424809a5432bf068667aac177 upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index a6c1dd1cf5a17a7806401e7b6fb97c3e2ceacd26..9cecb42eb49849df94533acb5c34af3248a27289 100644 (file)
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -259,6 +259,7 @@ int __init linux_main(int argc, char **argv)
        unsigned long avail, diff;
        unsigned long virtmem_size, max_physmem;
        unsigned int i, add;
+       unsigned long stack;
        char * mode;
 
        for (i = 1; i < argc; i++) {
@@ -347,7 +348,9 @@ 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;