[PATCH] Expanded bad page handling

The page allocator has traditionally just gone BUG when it sees a page
in a bad state.  This is usually due to hardware errors, sometimes
software errors.

I'm proposing that we not go BUG() any more, but print lots (and lots)
of diagnostic info and try to continue.

Might be a bit controversial.

mm/page_alloc.c

@@ -72,6 +72,17 @@ static void bad_page(const char *function, struct page *page)
 	printk("flags:0x%08lx mapping:%p mapped:%d count:%d\n",
 		page->flags, page->mapping,
 		page_mapped(page), page_count(page));
+	printk("Backtrace:\n");
+	dump_stack();
+	printk("Trying to fix it up, but a reboot is needed\n");
+	page->flags &= ~(1 << PG_private	|
+			1 << PG_locked	|
+			1 << PG_lru	|
+			1 << PG_active	|
+			1 << PG_dirty	|
+			1 << PG_writeback);
+	set_page_count(page, 0);
+	page->mapping = NULL;
 }
 
 /*