[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/include/linux/rmap.h b/include/linux/rmap.h
index 36f8503..bdd2772 100644 (file)
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -72,7 +72,7 @@ void __anon_vma_link(struct vm_area_struct *);
 void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_new_anon_rmap(struct page *, struct vm_area_struct *, unsigned long);
 void page_add_file_rmap(struct page *);
-void page_remove_rmap(struct page *);
+void page_remove_rmap(struct page *, struct vm_area_struct *);
 
 /**
  * page_dup_rmap - duplicate pte mapping to a page

diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index 8d66761..45b3553 100644 (file)
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -189,7 +189,7 @@ __xip_unmap (struct address_space * mapping,
                        /* 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);

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

diff --git a/mm/memory.c b/mm/memory.c
index c00bac6..563792f 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -681,7 +681,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
                                        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 @@ gotten:
        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);

diff --git a/mm/rmap.c b/mm/rmap.c
index d8a842a..b3deda8 100644 (file)
--- 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 @@ void page_add_file_rmap(struct page *page)
  *
  * 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 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
                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 @@ static void try_to_unmap_cluster(unsigned long cursor,
                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)--;