[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 <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 6f3f7db..66ec430 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -514,6 +514,13 @@
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,