[PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_sem

[linux-2.6] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 6f3f7db27128d45443ba114e93e8f31802cbef24..dfbb89f99a15a610b9463ea84a35068712187d23 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -20,13 +20,13 @@
 /*
  * Lock ordering in mm:
  *
- * inode->i_sem        (while writing or truncating, not reading or faulting)
+ * inode->i_mutex      (while writing or truncating, not reading or faulting)
  *   inode->i_alloc_sem
  *
  * When a page fault occurs in writing from user to file, down_read
- * of mmap_sem nests within i_sem; in sys_msync, i_sem nests within
- * down_read of mmap_sem; i_sem and down_write of mmap_sem are never
- * taken together; in truncation, i_sem is taken outermost.
+ * of mmap_sem nests within i_mutex; in sys_msync, i_mutex nests within
+ * down_read of mmap_sem; i_mutex and down_write of mmap_sem are never
+ * taken together; in truncation, i_mutex is taken outermost.
  *
  * mm->mmap_sem
  *   page->flags PG_locked (lock_page)
@@ -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,