commit 7de6b8057976584e5a422574cae4dd21c677b4d4
author Nick Piggin <nickpiggin@yahoo.com.au> Fri Dec 22 01:09:33 2006 -0800
committer Linus Torvalds <torvalds@woody.osdl.org> Fri Dec 22 08:55:49 2006 -0800
tree 900bc533401715eec4e44b73e388a74f08b3f1a5
parent 19900cdee29c812857ce938ab449e1053d516252

[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>

mm/filemap_xip.c

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 8d667617..45b3553 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -189,7 +189,7 @@
 			/* Nuke the page table entry. */
 			flush_cache_page(vma, address, pte_pfn(*pte));
 			pteval = ptep_clear_flush(vma, address, pte);
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			dec_mm_counter(mm, file_rss);
 			BUG_ON(pte_dirty(pteval));
 			pte_unmap_unlock(pte, ptl);

mm/fremap.c

diff --git a/mm/fremap.c b/mm/fremap.c
index b77a002..4e3f53d 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -33,7 +33,7 @@
 		if (page) {
 			if (pte_dirty(pte))
 				set_page_dirty(page);
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			page_cache_release(page);
 		}
 	} else {

mm/memory.c

diff --git a/mm/memory.c b/mm/memory.c
index c00bac6..563792f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -681,7 +681,7 @@
 					mark_page_accessed(page);
 				file_rss--;
 			}
-			page_remove_rmap(page);
+			page_remove_rmap(page, vma);
 			tlb_remove_page(tlb, page);
 			continue;
 		}
@@ -1586,7 +1586,7 @@
 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 	if (likely(pte_same(*page_table, orig_pte))) {
 		if (old_page) {
-			page_remove_rmap(old_page);
+			page_remove_rmap(old_page, vma);
 			if (!PageAnon(old_page)) {
 				dec_mm_counter(mm, file_rss);
 				inc_mm_counter(mm, anon_rss);

mm/rmap.c

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)--;