Re: do we want to kill VM_RESERVED or not? [was Re: 2.6.5-rc1-aa3]

[Andrea Arcangeli <andrea@suse.de>]

On Mon, Mar 22, 2004 at 01:10:38PM +0100, Marc-Christian Petersen wrote:
> And VMware won't work at all. Booting a VMware Image triggers the 2 warnings 
> and the kernel BUG and the screen stays black in VMware.

I see, the below patch will avoid your oops (I also removed the stack
trace dump from memory.c since it's useless to get the stack trace from
there and this will reduce the noise).

--- x/mm/memory.c.~1~	2004-03-21 15:21:42.000000000 +0100
+++ x/mm/memory.c	2004-03-22 13:40:26.852849384 +0100
@@ -324,9 +324,11 @@ skip_copy_pte_range:
 					 * Device driver pages must not be
 					 * tracked by the VM for unmapping.
 					 */
-					BUG_ON(!page_mapped(page));
-					BUG_ON(!page->mapping);
-					page_add_rmap(page, vma, address, PageAnon(page));
+					if (likely(page_mapped(page) && page->mapping))
+						page_add_rmap(page, vma, address, PageAnon(page));
+					else
+						printk("Badness in %s at %s:%d\n",
+						       __FUNCTION__, __FILE__, __LINE__);
 				} else {
 					BUG_ON(page_mapped(page));
 					BUG_ON(page->mapping);
@@ -1429,7 +1431,9 @@ retry:
 	 * real anonymous pages, they're "device" reserved pages instead.
 	 */
 	reserved = !!(vma->vm_flags & VM_RESERVED);
-	WARN_ON(reserved == pageable);
+	if (unlikely(reserved == pageable))
+		printk("Badness in %s at %s:%d\n",
+		       __FUNCTION__, __FILE__, __LINE__);
 
 	/*
 	 * Should we do an early C-O-W break?

many thanks for the help!