diff -urN 2.2.14pre12-set_blocksize/fs/buffer.c 2.2.14pre12-set_blocksize-debug/fs/buffer.c
--- 2.2.14pre12-set_blocksize/fs/buffer.c	Sun Dec 12 17:25:18 1999
+++ 2.2.14pre12-set_blocksize-debug/fs/buffer.c	Tue Dec 14 17:01:22 1999
@@ -641,6 +641,14 @@
 	}
 }
 
+static void show_stack_trace(struct buffer_head * bh)
+{
+	int i;
+
+	for (i = 0; i < BH_TRACE_SIZE; i++)
+		printk("[<%08lu>]\n", bh->b_trace[i]);
+}
+
 void set_blocksize(kdev_t dev, int size)
 {
 	extern int *blksize_size[];
@@ -697,6 +705,7 @@
 				       "b_count %d, dev %s, block %lu, from %p\n",
 				       bh->b_count, bdevname(bh->b_dev),
 				       bh->b_blocknr, __builtin_return_address(0));
+				show_stack_trace(bh);
 			}
 			if (slept)
 				goto again;
@@ -734,6 +743,22 @@
 	unlock_buffer(bh);
 }
 
+static void fill_stack_trace(struct buffer_head * bh)
+{
+	unsigned long *stack;
+	extern char *get_options(char *str, int *ints);
+	int i, j;
+
+	stack = (unsigned long *) &stack;
+	for (j = i = 0; j < 300 && i < BH_TRACE_SIZE; j++)
+	{
+		unsigned long x = *++stack;
+		if (x > (unsigned long) &get_options &&
+		    x < (unsigned long) &vsprintf)
+			bh->b_trace[i++] = x;
+	}
+}
+
 /*
  * Ok, this is getblk, and it isn't very clear, again to hinder
  * race-conditions. Most of the code is seldom used, (ie repeating),
@@ -770,6 +795,7 @@
 	 */
 	init_buffer(bh, dev, block, end_buffer_io_sync, NULL);
 	bh->b_state=0;
+	fill_stack_trace(bh);
 	insert_into_queues(bh);
 	return bh;
 
diff -urN 2.2.14pre12-set_blocksize/include/linux/fs.h 2.2.14pre12-set_blocksize-debug/include/linux/fs.h
--- 2.2.14pre12-set_blocksize/include/linux/fs.h	Sun Dec 12 17:45:06 1999
+++ 2.2.14pre12-set_blocksize-debug/include/linux/fs.h	Tue Dec 14 16:51:58 1999
@@ -222,6 +222,8 @@
 	 */
 	void (*b_end_io)(struct buffer_head *bh, int uptodate);
 	void *b_dev_id;
+#define BH_TRACE_SIZE 15
+	unsigned long b_trace[BH_TRACE_SIZE];
 };
 
 typedef void (bh_end_io_t)(struct buffer_head *bh, int uptodate);