[PATCH] mm: more rmap debugging
Add more debugging in the rmap code in an attempt to locate to source of
the occasional "mapcount went negative" assertions.
Cc: Hugh Dickins <hugh@veritas.com>
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 d8a842a..b3deda8 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -47,6 +47,7 @@
#include <linux/rmap.h>
#include <linux/rcupdate.h>
#include <linux/module.h>
+#include <linux/kallsyms.h>
#include <asm/tlbflush.h>
@@ -567,14 +568,20 @@
*
* The caller needs to hold the pte lock.
*/
-void page_remove_rmap(struct page *page)
+void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
{
if (atomic_add_negative(-1, &page->_mapcount)) {
if (unlikely(page_mapcount(page) < 0)) {
printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
+ printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(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);
+ print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops);
+ if (vma->vm_ops)
+ print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);
+ if (vma->vm_file && vma->vm_file->f_op)
+ print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap);
BUG();
}
@@ -679,7 +686,7 @@
dec_mm_counter(mm, file_rss);
- page_remove_rmap(page);
+ page_remove_rmap(page, vma);
page_cache_release(page);
out_unmap:
@@ -769,7 +776,7 @@
if (pte_dirty(pteval))
set_page_dirty(page);
- page_remove_rmap(page);
+ page_remove_rmap(page, vma);
page_cache_release(page);
dec_mm_counter(mm, file_rss);
(*mapcount)--;