[PATCH] rmap: additional diagnostics in page_remove_rmap()

We seem to be hitting this assertion failure too often for it to be hardware bugs. Cc: Hugh Dickins <[email protected]> Cc: Nick Piggin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mgowda · Jan 9, 2006 · ef2bf0d · ef2bf0d
1 parent cd105df
commit ef2bf0d
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/mm/rmap.c b/mm/rmap.c
@@ -514,6 +514,13 @@ void page_add_file_rmap(struct page *page)
 void page_remove_rmap(struct page *page)
 {
 	if (atomic_add_negative(-1, &page->_mapcount)) {
+		if (page_mapcount(page) < 0) {
+			printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
+			printk (KERN_EMERG "  page->flags = %lx\n", page->flags);
+			printk (KERN_EMERG "  page->count = %x\n", page_count(page));
+			printk (KERN_EMERG "  page->mapping = %p\n", page->mapping);
+		}
+
 		BUG_ON(page_mapcount(page) < 0);
 		/*
 		 * It would be tidy to reset the PageAnon mapping here,