[PATCH] uml: MADV_REMOVE fixes

MADV_REMOVE fixes - change the test mapping to be MAP_SHARED instead of
MAP_PRIVATE, as MADV_REMOVE on MAP_PRIVATE maps won't work.  Also, use
the kernel's definition of MADV_REMOVE instead of hardcoding it if there
isn't a libc definition.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/include/sysdep-i386/kernel-offsets.h

@@ -1,6 +1,7 @@
 #include <linux/stddef.h>
 #include <linux/sched.h>
 #include <linux/elf.h>
+#include <asm/mman.h>
 
 #define DEFINE(sym, val) \
 	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
@@ -16,6 +17,7 @@
 void foo(void)
 {
 	OFFSET(HOST_TASK_DEBUGREGS, task_struct, thread.arch.debugregs);
+	DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
 #ifdef CONFIG_MODE_TT
 	OFFSET(HOST_TASK_EXTERN_PID, task_struct, thread.mode.tt.extern_pid);
 #endif

arch/um/include/sysdep-x86_64/kernel-offsets.h

@@ -4,6 +4,7 @@
 #include <linux/time.h>
 #include <linux/elf.h>
 #include <asm/page.h>
+#include <asm/mman.h>
 
 #define DEFINE(sym, val) \
 	asm volatile("\n->" #sym " %0 " #val : : "i" (val))
@@ -18,6 +19,7 @@
 
 void foo(void)
 {
+	DEFINE(KERNEL_MADV_REMOVE, MADV_REMOVE);
 #ifdef CONFIG_MODE_TT
 	OFFSET(HOST_TASK_EXTERN_PID, task_struct, thread.mode.tt.extern_pid);
 #endif

arch/um/os-Linux/process.c

@@ -190,7 +190,7 @@ int os_unmap_memory(void *addr, int len)
 }
 
 #ifndef MADV_REMOVE
-#define MADV_REMOVE	0x5		/* remove these pages & resources */
+#define MADV_REMOVE KERNEL_MADV_REMOVE
 #endif
 
 int os_drop_memory(void *addr, int length)
@@ -216,7 +216,7 @@ int can_drop_memory(void)
 	}
 
 	addr = mmap64(NULL, UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
-		      MAP_PRIVATE, fd, 0);
+		      MAP_SHARED, fd, 0);
 	if(addr == MAP_FAILED){
 		printk("Mapping test memory file failed, err = %d\n", -errno);
 		return 0;