=== modified file 'storage/innodb_plugin/buf/buf0buf.c'
--- storage/innodb_plugin/buf/buf0buf.c	revid:jimmy.yang@oracle.com-20110504100621-lztcsjgtrvlq7q8j
+++ storage/innodb_plugin/buf/buf0buf.c	2011-05-16 19:25:06 +0000
@@ -2095,7 +2095,6 @@ loop:
 		block = (buf_block_t*) buf_page_hash_get(space, offset);
 	}
 
-loop2:
 	if (block == NULL) {
 		/* Page not in buf_pool: needs to be read from file */
 
@@ -2177,6 +2176,11 @@ wait_until_unfixed:
 			goto loop;
 		}
 
+		/* Buffer-fix the block so that it cannot be evicted
+		or relocated while we are attempting to allocate an
+		uncompressed page. */
+		bpage->buf_fix_count++;
+
 		/* Allocate an uncompressed page. */
 		buf_pool_mutex_exit();
 		mutex_exit(&buf_pool_zip_mutex);
@@ -2186,32 +2190,21 @@ wait_until_unfixed:
 
 		buf_pool_mutex_enter();
 		mutex_enter(&block->mutex);
-
-		{
-			buf_page_t*	hash_bpage
-				= buf_page_hash_get(space, offset);
-
-			if (UNIV_UNLIKELY(bpage != hash_bpage)) {
-				/* The buf_pool->page_hash was modified
-				while buf_pool_mutex was released.
-				Free the block that was allocated. */
-
-				buf_LRU_block_free_non_file_page(block);
-				mutex_exit(&block->mutex);
-
-				block = (buf_block_t*) hash_bpage;
-				goto loop2;
-			}
-		}
+		mutex_enter(&buf_pool_zip_mutex);
+		bpage->buf_fix_count--;
+		/* Buffer-fixing prevents the page_hash from changing. */
+		ut_ad(bpage == buf_page_hash_get(space, offset));
 
 		if (UNIV_UNLIKELY
 		    (bpage->buf_fix_count
 		     || buf_page_get_io_fix(bpage) != BUF_IO_NONE)) {
 
-			/* The block was buffer-fixed or I/O-fixed
-			while buf_pool_mutex was not held by this thread.
-			Free the block that was allocated and try again.
-			This should be extremely unlikely. */
+			mutex_exit(&buf_pool_zip_mutex);
+			/* The block was buffer-fixed or I/O-fixed while
+			buf_pool_mutex was not held by this thread.
+			Free the block that was allocated and retry.
+			This should be extremely unlikely, for example,
+			if buf_page_get_zip() was invoked. */
 
 			buf_LRU_block_free_non_file_page(block);
 			mutex_exit(&block->mutex);
@@ -2222,8 +2215,6 @@ wait_until_unfixed:
 		/* Move the compressed page from bpage to block,
 		and uncompress it. */
 
-		mutex_enter(&buf_pool_zip_mutex);
-
 		buf_relocate(bpage, &block->page);
 		buf_block_init_low(block);
 		block->lock_hash_val = lock_rec_hash(space, offset);