Applied innodb-5.1-ss1004

Fixes:
- Bug #15815: Very poor performance with multiple queries running concurrently
- Bug #22868: 'Thread thrashing' with > 50 concurrent conns under an upd-intensive workloadw
- Bug #24089: Race condition in fil_flush_file_spaces()


storage/innobase/btr/btr0btr.c:
  Applied innodb-5.1-ss1004
  
  Revision r934:
  btr_lift_page_up(): Set new page levels in all ancestor pages, not just
  in the father page.
  
  btr0btr.h: Add a BTR_MAX_LEVELS define.
storage/innobase/buf/buf0buf.c:
  Applied innodb-5.1-ss1004
  
  Revision r999:
  Reduce buffer pool mutex contention under >= 4 big concurrent
  CPU-bound SELECT queries.  (Bug #22868)
  
  Fix: replace the mutex by one mutex protecting the 'flush list'
  (and the free list) and several mutexes protecting portions of the
  buffer pool, where we keep several indivudual LRU lists of pages.
  
  This patch is from Sunny Bains and Heikki Tuuri.
storage/innobase/buf/buf0flu.c:
  Applied innodb-5.1-ss1004
  
  Revision r999:
  Reduce buffer pool mutex contention under >= 4 big concurrent
  CPU-bound SELECT queries.  (Bug #22868)
  
  Fix: replace the mutex by one mutex protecting the 'flush list'
  (and the free list) and several mutexes protecting portions of the
  buffer pool, where we keep several indivudual LRU lists of pages.
  
  This patch is from Sunny Bains and Heikki Tuuri.
storage/innobase/buf/buf0lru.c:
  Applied innodb-5.1-ss1004
  
  Revision r999:
  Reduce buffer pool mutex contention under >= 4 big concurrent
  CPU-bound SELECT queries.  (Bug #22868)
  
  Fix: replace the mutex by one mutex protecting the 'flush list'
  (and the free list) and several mutexes protecting portions of the
  buffer pool, where we keep several indivudual LRU lists of pages.
  
  This patch is from Sunny Bains and Heikki Tuuri.
  
  
  Revision r1004:
  UT_LIST_REMOVE(): Invalidate the node pointers #ifdef UNIV_DEBUG.
  
  buf_LRU_invalidate_tablespace(): Invoke UT_LIST_GET_PREV(LRU, block)
  before UT_LIST_REMOVE(LRU, buf_pool->LRU, block).
storage/innobase/dict/dict0crea.c:
  Applied innodb-5.1-ss1004
  
  Revision r973:
  Do not break the latching order in TRUNCATE TABLE.
  
  dict_truncate_index_tree(): Replace parameter rec_t* rec with
  btr_pcur_t* pcur.  Reposition pcur before calling btr_create().
  
  sync_thread_add_level(): Remove the relaxation of the assertion added in r968.
storage/innobase/fil/fil0fil.c:
  Applied innodb-5.1-ss1004
  
  Revision r1002:
  fil_flush_file_spaces(): Copy the system->unflushed_spaces list to an
  array while holding the mutex.  This removes the crash-triggering
  race condition that was introduced when fixing Bug 15653.  (Bug #24089)
storage/innobase/include/btr0btr.h:
  Applied innodb-5.1-ss1004
  
  Revision r934:
  btr_lift_page_up(): Set new page levels in all ancestor pages, not just
  in the father page.
  
  btr0btr.h: Add a BTR_MAX_LEVELS define.
storage/innobase/include/buf0buf.h:
  Applied innodb-5.1-ss1004
  
  Revision r999:
  Reduce buffer pool mutex contention under >= 4 big concurrent
  CPU-bound SELECT queries.  (Bug #22868)
  
  Fix: replace the mutex by one mutex protecting the 'flush list'
  (and the free list) and several mutexes protecting portions of the
  buffer pool, where we keep several indivudual LRU lists of pages.
  
  This patch is from Sunny Bains and Heikki Tuuri.
storage/innobase/include/buf0buf.ic:
  Applied innodb-5.1-ss1004
  
  Revision r999:
  Reduce buffer pool mutex contention under >= 4 big concurrent
  CPU-bound SELECT queries.  (Bug #22868)
  
  Fix: replace the mutex by one mutex protecting the 'flush list'
  (and the free list) and several mutexes protecting portions of the
  buffer pool, where we keep several indivudual LRU lists of pages.
  
  This patch is from Sunny Bains and Heikki Tuuri.
storage/innobase/include/dict0crea.h:
  Applied innodb-5.1-ss1004
  
  Revision r973:
  Do not break the latching order in TRUNCATE TABLE.
  
  dict_truncate_index_tree(): Replace parameter rec_t* rec with
  btr_pcur_t* pcur.  Reposition pcur before calling btr_create().
  
  sync_thread_add_level(): Remove the relaxation of the assertion added in r968.
storage/innobase/include/ut0lst.h:
  Applied innodb-5.1-ss1004
  
  Revision r1004:
  UT_LIST_REMOVE(): Invalidate the node pointers #ifdef UNIV_DEBUG.
  
  buf_LRU_invalidate_tablespace(): Invoke UT_LIST_GET_PREV(LRU, block)
  before UT_LIST_REMOVE(LRU, buf_pool->LRU, block).
storage/innobase/row/row0mysql.c:
  Applied innodb-5.1-ss1004
  
  Revision r973:
  Do not break the latching order in TRUNCATE TABLE.
  
  dict_truncate_index_tree(): Replace parameter rec_t* rec with
  btr_pcur_t* pcur.  Reposition pcur before calling btr_create().
  
  sync_thread_add_level(): Remove the relaxation of the assertion added in r968.

3 files changed, 206 insertions, 77 deletions

diff --git a/storage/innobase/buf/buf0buf.c b/storage/innobase/buf/buf0buf.c
index 222acc015a6..99e365d6129 100644
--- a/storage/innobase/buf/buf0buf.c
+++ b/storage/innobase/buf/buf0buf.c
@@ -221,6 +221,9 @@ in the free list to the frames.
 5) When we have AWE enabled, we disable adaptive hash indexes.
 */
 
+/* Value in microseconds */
+static const int WAIT_FOR_READ	= 20000;
+
 buf_pool_t*	buf_pool = NULL; /* The buffer buf_pool of the database */
 
 #ifdef UNIV_DEBUG
@@ -539,6 +542,8 @@ buf_block_init(
 
 	block->n_pointers = 0;
 
+	mutex_create(&block->mutex, SYNC_BUF_BLOCK);
+
 	rw_lock_create(&block->lock, SYNC_LEVEL_VARYING);
 	ut_ad(rw_lock_validate(&(block->lock)));
 
@@ -813,8 +818,15 @@ buf_awe_map_page_to_frame(
 	bck = UT_LIST_GET_LAST(buf_pool->awe_LRU_free_mapped);
 
 	while (bck) {
-		if (bck->state == BUF_BLOCK_FILE_PAGE
-		    && (bck->buf_fix_count != 0 || bck->io_fix != 0)) {
+		ibool skip;
+
+		mutex_enter(&bck->mutex);
+
+		skip = (bck->state == BUF_BLOCK_FILE_PAGE
+			&& (bck->buf_fix_count != 0 || bck->io_fix != 0));
+
+		if (skip) {
+			mutex_exit(&bck->mutex);
 
 			/* We have to skip this */
 			bck = UT_LIST_GET_PREV(awe_LRU_free_mapped, bck);
@@ -848,6 +860,8 @@ buf_awe_map_page_to_frame(
 
 			buf_pool->n_pages_awe_remapped++;
 
+			mutex_exit(&bck->mutex);
+
 			return;
 		}
 	}
@@ -886,13 +900,22 @@ buf_block_make_young(
 /*=================*/
 	buf_block_t*	block)	/* in: block to make younger */
 {
+#ifdef UNIV_SYNC_DEBUG
+	ut_ad(!mutex_own(&(buf_pool->mutex)));
+#endif /* UNIV_SYNC_DEBUG */
+
+	/* Note that we read freed_page_clock's without holding any mutex:
+	this is allowed since the result is used only in heuristics */
+
 	if (buf_pool->freed_page_clock >= block->freed_page_clock
-	    + 1 + (buf_pool->curr_size / 1024)) {
+				+ 1 + (buf_pool->curr_size / 4)) {
 
+		mutex_enter(&buf_pool->mutex);
 		/* There has been freeing activity in the LRU list:
 		best to move to the head of the LRU list */
 
 		buf_LRU_make_block_young(block);
+		mutex_exit(&buf_pool->mutex);
 	}
 }
 
@@ -927,12 +950,16 @@ buf_block_free(
 /*===========*/
 	buf_block_t*	block)	/* in, own: block to be freed */
 {
-	ut_a(block->state != BUF_BLOCK_FILE_PAGE);
-
 	mutex_enter(&(buf_pool->mutex));
 
+	mutex_enter(&block->mutex);
+
+	ut_a(block->state != BUF_BLOCK_FILE_PAGE);
+
 	buf_LRU_block_free_non_file_page(block);
 
+	mutex_exit(&block->mutex);
+
 	mutex_exit(&(buf_pool->mutex));
 }
 
@@ -1151,9 +1178,8 @@ buf_page_get_gen(
 #endif
 	buf_pool->n_page_gets++;
 loop:
-	mutex_enter_fast(&(buf_pool->mutex));
-
 	block = NULL;
+	mutex_enter_fast(&(buf_pool->mutex));
 
 	if (guess) {
 		block = buf_block_align(guess);
@@ -1191,6 +1217,8 @@ loop:
 		goto loop;
 	}
 
+	mutex_enter(&block->mutex);
+
 	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
 
 	must_read = FALSE;
@@ -1200,9 +1228,9 @@ loop:
 		must_read = TRUE;
 
 		if (mode == BUF_GET_IF_IN_POOL) {
-
 			/* The page is only being read to buffer */
-			mutex_exit(&(buf_pool->mutex));
+			mutex_exit(&buf_pool->mutex);
+			mutex_exit(&block->mutex);
 
 			return(NULL);
 		}
@@ -1226,7 +1254,7 @@ loop:
 #else
 	buf_block_buf_fix_inc(block);
 #endif
-	buf_block_make_young(block);
+	mutex_exit(&buf_pool->mutex);
 
 	/* Check if this is the first access to the page */
 
@@ -1234,10 +1262,13 @@ loop:
 
 	block->accessed = TRUE;
 
+	mutex_exit(&block->mutex);
+
+	buf_block_make_young(block);
+
 #ifdef UNIV_DEBUG_FILE_ACCESSES
 	ut_a(block->file_page_was_freed == FALSE);
 #endif
-	mutex_exit(&(buf_pool->mutex));
 
 #ifdef UNIV_DEBUG
 	buf_dbg_counter++;
@@ -1262,13 +1293,14 @@ loop:
 		}
 
 		if (!success) {
-			mutex_enter(&(buf_pool->mutex));
+			mutex_enter(&block->mutex);
 
 			block->buf_fix_count--;
+
+			mutex_exit(&block->mutex);
 #ifdef UNIV_SYNC_DEBUG
 			rw_lock_s_unlock(&(block->debug_latch));
 #endif
-			mutex_exit(&(buf_pool->mutex));
 
 			return(NULL);
 		}
@@ -1279,18 +1311,16 @@ loop:
 			completes */
 
 			for (;;) {
-				mutex_enter(&(buf_pool->mutex));
+				mutex_enter(&block->mutex);
 
 				if (block->io_fix == BUF_IO_READ) {
 
-					mutex_exit(&(buf_pool->mutex));
-
-					/* Sleep 20 milliseconds */
+					mutex_exit(&block->mutex);
 
-					os_thread_sleep(20000);
+					os_thread_sleep(WAIT_FOR_READ);
 				} else {
 
-					mutex_exit(&(buf_pool->mutex));
+					mutex_exit(&block->mutex);
 
 					break;
 				}
@@ -1349,14 +1379,14 @@ buf_page_optimistic_get_func(
 	ut_ad(mtr && block);
 	ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
 
-	mutex_enter(&(buf_pool->mutex));
-
 	/* If AWE is used, block may have a different frame now, e.g., NULL */
 
+	mutex_enter(&block->mutex);
+
 	if (UNIV_UNLIKELY(block->state != BUF_BLOCK_FILE_PAGE)
 	    || UNIV_UNLIKELY(block->frame != guess)) {
-exit_func:
-		mutex_exit(&(buf_pool->mutex));
+
+		mutex_exit(&block->mutex);
 
 		return(FALSE);
 	}
@@ -1366,15 +1396,14 @@ exit_func:
 #else
 	buf_block_buf_fix_inc(block);
 #endif
-	buf_block_make_young(block);
-
-	/* Check if this is the first access to the page */
-
 	accessed = block->accessed;
-
 	block->accessed = TRUE;
 
-	mutex_exit(&(buf_pool->mutex));
+	mutex_exit(&block->mutex);
+
+	buf_block_make_young(block);
+
+	/* Check if this is the first access to the page */
 
 	ut_ad(!ibuf_inside() || ibuf_page(block->space, block->offset));
 
@@ -1389,13 +1418,16 @@ exit_func:
 	}
 
 	if (UNIV_UNLIKELY(!success)) {
-		mutex_enter(&(buf_pool->mutex));
+		mutex_enter(&block->mutex);
 
 		block->buf_fix_count--;
+
+		mutex_exit(&block->mutex);
+
 #ifdef UNIV_SYNC_DEBUG
 		rw_lock_s_unlock(&(block->debug_latch));
 #endif
-		goto exit_func;
+		return(FALSE);
 	}
 
 	if (UNIV_UNLIKELY(!UT_DULINT_EQ(modify_clock, block->modify_clock))) {
@@ -1408,13 +1440,16 @@ exit_func:
 			rw_lock_x_unlock(&(block->lock));
 		}
 
-		mutex_enter(&(buf_pool->mutex));
+		mutex_enter(&block->mutex);
 
 		block->buf_fix_count--;
+
+		mutex_exit(&block->mutex);
+
 #ifdef UNIV_SYNC_DEBUG
 		rw_lock_s_unlock(&(block->debug_latch));
 #endif
-		goto exit_func;
+		return(FALSE);
 	}
 
 	mtr_memo_push(mtr, block, fix_type);
@@ -1471,10 +1506,10 @@ buf_page_get_known_nowait(
 	ut_ad(mtr);
 	ut_ad((rw_latch == RW_S_LATCH) || (rw_latch == RW_X_LATCH));
 
-	mutex_enter(&(buf_pool->mutex));
-
 	block = buf_block_align(guess);
 
+	mutex_enter(&block->mutex);
+
 	if (block->state == BUF_BLOCK_REMOVE_HASH) {
 		/* Another thread is just freeing the block from the LRU list
 		of the buffer pool: do not try to access this page; this
@@ -1483,7 +1518,7 @@ buf_page_get_known_nowait(
 		we have already removed it from the page address hash table
 		of the buffer pool. */
 
-		mutex_exit(&(buf_pool->mutex));
+		mutex_exit(&block->mutex);
 
 		return(FALSE);
 	}
@@ -1495,12 +1530,12 @@ buf_page_get_known_nowait(
 #else
 	buf_block_buf_fix_inc(block);
 #endif
+	mutex_exit(&block->mutex);
+
 	if (mode == BUF_MAKE_YOUNG) {
 		buf_block_make_young(block);
 	}
 
-	mutex_exit(&(buf_pool->mutex));
-
 	ut_ad(!ibuf_inside() || (mode == BUF_KEEP_OLD));
 
 	if (rw_latch == RW_S_LATCH) {
@@ -1514,13 +1549,15 @@ buf_page_get_known_nowait(
 	}
 
 	if (!success) {
-		mutex_enter(&(buf_pool->mutex));
+		mutex_enter(&block->mutex);
 
 		block->buf_fix_count--;
+
+		mutex_exit(&block->mutex);
+
 #ifdef UNIV_SYNC_DEBUG
 		rw_lock_s_unlock(&(block->debug_latch));
 #endif
-		mutex_exit(&(buf_pool->mutex));
 
 		return(FALSE);
 	}
@@ -1568,7 +1605,6 @@ buf_page_init_for_backup_restore(
 	block->offset		= offset;
 
 	block->lock_hash_val	= 0;
-	block->lock_mutex	= NULL;
 
 	block->freed_page_clock = 0;
 
@@ -1601,6 +1637,7 @@ buf_page_init(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&(block->mutex)));
 #endif /* UNIV_SYNC_DEBUG */
 	ut_a(block->state != BUF_BLOCK_FILE_PAGE);
 
@@ -1615,7 +1652,6 @@ buf_page_init(
 	block->index		= NULL;
 
 	block->lock_hash_val	= lock_rec_hash(space, offset);
-	block->lock_mutex	= NULL;
 
 	/* Insert into the hash table of file pages */
 
@@ -1709,6 +1745,7 @@ buf_page_init_for_read(
 	ut_a(block);
 
 	mutex_enter(&(buf_pool->mutex));
+	mutex_enter(&block->mutex);
 
 	if (fil_tablespace_deleted_or_being_deleted_in_mem(
 		    space, tablespace_version)) {
@@ -1722,7 +1759,9 @@ buf_page_init_for_read(
 		    deleted or is being deleted, or the page is
 		    already in buf_pool, return */
 
+		mutex_exit(&block->mutex);
 		    mutex_exit(&(buf_pool->mutex));
+
 		    buf_block_free(block);
 
 		    if (mode == BUF_READ_IBUF_PAGES_ONLY) {
@@ -1742,6 +1781,7 @@ buf_page_init_for_read(
 	buf_LRU_add_block(block, TRUE);		/* TRUE == to old blocks */
 
 	block->io_fix = BUF_IO_READ;
+
 	buf_pool->n_pend_reads++;
 
 	/* We set a pass-type x-lock on the frame because then the same
@@ -1753,6 +1793,7 @@ buf_page_init_for_read(
 
 	rw_lock_x_lock_gen(&(block->lock), BUF_IO_READ);
 
+	mutex_exit(&block->mutex);
 	mutex_exit(&(buf_pool->mutex));
 
 	if (mode == BUF_READ_IBUF_PAGES_ONLY) {
@@ -1817,6 +1858,8 @@ buf_page_create(
 
 	block = free_block;
 
+	mutex_enter(&block->mutex);
+
 	buf_page_init(space, offset, block);
 
 	/* The block must be put to the LRU list */
@@ -1827,13 +1870,15 @@ buf_page_create(
 #else
 	buf_block_buf_fix_inc(block);
 #endif
+	buf_pool->n_pages_created++;
+
+	mutex_exit(&(buf_pool->mutex));
+
 	mtr_memo_push(mtr, block, MTR_MEMO_BUF_FIX);
 
 	block->accessed = TRUE;
 
-	buf_pool->n_pages_created++;
-
-	mutex_exit(&(buf_pool->mutex));
+	mutex_exit(&block->mutex);
 
 	/* Delete possible entries for the page from the insert buffer:
 	such can exist if the page belonged to an index which was dropped */
@@ -1885,6 +1930,12 @@ buf_page_io_complete(
 
 	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
 
+	/* We do not need protect block->io_fix here by block->mutex to read
+	it because this is the only function where we can change the value
+	from BUF_IO_READ or BUF_IO_WRITE to some other value, and our code
+	ensures that this is the only thread that handles the i/o for this
+	block. */
+
 	io_type = block->io_fix;
 
 	if (io_type == BUF_IO_READ) {
@@ -1986,11 +2037,12 @@ buf_page_io_complete(
 		}
 	}
 
+	mutex_enter(&(buf_pool->mutex));
+	mutex_enter(&block->mutex);
+
 #ifdef UNIV_IBUF_DEBUG
 	ut_a(ibuf_count_get(block->space, block->offset) == 0);
 #endif
-	mutex_enter(&(buf_pool->mutex));
-
 	/* Because this thread which does the unlocking is not the same that
 	did the locking, we use a pass value != 0 in unlock, which simply
 	removes the newest lock debug record, without checking the thread
@@ -2033,6 +2085,7 @@ buf_page_io_complete(
 #endif /* UNIV_DEBUG */
 	}
 
+	mutex_exit(&block->mutex);
 	mutex_exit(&(buf_pool->mutex));
 
 #ifdef UNIV_DEBUG
@@ -2095,6 +2148,8 @@ buf_validate(void)
 
 		block = buf_pool_get_nth_block(buf_pool, i);
 
+		mutex_enter(&block->mutex);
+
 		if (block->state == BUF_BLOCK_FILE_PAGE) {
 
 			ut_a(buf_page_hash_get(block->space,
@@ -2139,6 +2194,8 @@ buf_validate(void)
 		} else if (block->state == BUF_BLOCK_NOT_USED) {
 			n_free++;
 		}
+
+		mutex_exit(&block->mutex);
 	}
 
 	if (n_lru + n_free > buf_pool->curr_size) {
@@ -2286,9 +2343,14 @@ buf_get_latched_pages_number(void)
 
 		block = buf_pool_get_nth_block(buf_pool, i);
 
-		if (((block->buf_fix_count != 0) || (block->io_fix != 0))
-		    && block->magic_n == BUF_BLOCK_MAGIC_N) {
-			fixed_pages_number++;
+		if (block->magic_n == BUF_BLOCK_MAGIC_N) {
+			mutex_enter(&block->mutex);
+
+			if (block->buf_fix_count != 0 || block->io_fix != 0) {
+				fixed_pages_number++;
+			}
+
+			mutex_exit(&block->mutex);
 		}
 	}
 
@@ -2458,6 +2520,8 @@ buf_all_freed(void)
 
 		block = buf_pool_get_nth_block(buf_pool, i);
 
+		mutex_enter(&block->mutex);
+
 		if (block->state == BUF_BLOCK_FILE_PAGE) {
 
 			if (!buf_flush_ready_for_replace(block)) {
@@ -2469,6 +2533,8 @@ buf_all_freed(void)
 				ut_error;
 			}
 		}
+
+		mutex_exit(&block->mutex);
 	}
 
 	mutex_exit(&(buf_pool->mutex));
diff --git a/storage/innobase/buf/buf0flu.c b/storage/innobase/buf/buf0flu.c
index 8ef8c3b9358..49b81196a64 100644
--- a/storage/innobase/buf/buf0flu.c
+++ b/storage/innobase/buf/buf0flu.c
@@ -113,6 +113,7 @@ buf_flush_ready_for_replace(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&block->mutex));
 #endif /* UNIV_SYNC_DEBUG */
 	if (block->state != BUF_BLOCK_FILE_PAGE) {
 		ut_print_timestamp(stderr);
@@ -148,6 +149,7 @@ buf_flush_ready_for_flush(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&(block->mutex)));
 #endif /* UNIV_SYNC_DEBUG */
 	ut_a(block->state == BUF_BLOCK_FILE_PAGE);
 
@@ -559,8 +561,15 @@ buf_flush_try_page(
 
 	ut_a(!block || block->state == BUF_BLOCK_FILE_PAGE);
 
+	if (!block) {
+		mutex_exit(&(buf_pool->mutex));
+		return(0);
+	}
+
+	mutex_enter(&block->mutex);
+
 	if (flush_type == BUF_FLUSH_LIST
-	    && block && buf_flush_ready_for_flush(block, flush_type)) {
+	    && buf_flush_ready_for_flush(block, flush_type)) {
 
 		block->io_fix = BUF_IO_WRITE;
 
@@ -598,6 +607,7 @@ buf_flush_try_page(
 			locked = TRUE;
 		}
 
+		mutex_exit(&block->mutex);
 		mutex_exit(&(buf_pool->mutex));
 
 		if (!locked) {
@@ -618,7 +628,7 @@ buf_flush_try_page(
 
 		return(1);
 
-	} else if (flush_type == BUF_FLUSH_LRU && block
+	} else if (flush_type == BUF_FLUSH_LRU
 		   && buf_flush_ready_for_flush(block, flush_type)) {
 
 		/* VERY IMPORTANT:
@@ -659,13 +669,14 @@ buf_flush_try_page(
 		buf_pool mutex: this ensures that the latch is acquired
 		immediately. */
 
+		mutex_exit(&block->mutex);
 		mutex_exit(&(buf_pool->mutex));
 
 		buf_flush_write_block_low(block);
 
 		return(1);
 
-	} else if (flush_type == BUF_FLUSH_SINGLE_PAGE && block
+	} else if (flush_type == BUF_FLUSH_SINGLE_PAGE
 		   && buf_flush_ready_for_flush(block, flush_type)) {
 
 		block->io_fix = BUF_IO_WRITE;
@@ -692,6 +703,7 @@ buf_flush_try_page(
 
 		(buf_pool->n_flush[flush_type])++;
 
+		mutex_exit(&block->mutex);
 		mutex_exit(&(buf_pool->mutex));
 
 		rw_lock_s_lock_gen(&(block->lock), BUF_IO_WRITE);
@@ -709,11 +721,12 @@ buf_flush_try_page(
 		buf_flush_write_block_low(block);
 
 		return(1);
-	} else {
-		mutex_exit(&(buf_pool->mutex));
-
-		return(0);
 	}
+
+	mutex_exit(&block->mutex);
+	mutex_exit(&(buf_pool->mutex));
+
+	return(0);
 }
 
 /***************************************************************
@@ -758,34 +771,48 @@ buf_flush_try_neighbors(
 		block = buf_page_hash_get(space, i);
 		ut_a(!block || block->state == BUF_BLOCK_FILE_PAGE);
 
-		if (block && flush_type == BUF_FLUSH_LRU && i != offset
-		    && !block->old) {
+		if (!block) {
+
+			continue;
+
+		} else if (flush_type == BUF_FLUSH_LRU && i != offset
+			   && !block->old) {
 
 			/* We avoid flushing 'non-old' blocks in an LRU flush,
 			because the flushed blocks are soon freed */
 
 			continue;
-		}
+		} else {
 
-		if (block && buf_flush_ready_for_flush(block, flush_type)
-		    && (i == offset || block->buf_fix_count == 0)) {
-			/* We only try to flush those neighbors != offset
-			where the buf fix count is zero, as we then know that
-			we probably can latch the page without a semaphore
-			wait. Semaphore waits are expensive because we must
-			flush the doublewrite buffer before we start
-			waiting. */
+			mutex_enter(&block->mutex);
 
-			mutex_exit(&(buf_pool->mutex));
+			if (buf_flush_ready_for_flush(block, flush_type)
+			    && (i == offset || block->buf_fix_count == 0)) {
+				/* We only try to flush those
+				neighbors != offset where the buf fix count is
+				zero, as we then know that we probably can
+				latch the page without a semaphore wait.
+				Semaphore waits are expensive because we must
+				flush the doublewrite buffer before we start
+				waiting. */
 
-			/* Note: as we release the buf_pool mutex above, in
-			buf_flush_try_page we cannot be sure the page is still
-			in a flushable state: therefore we check it again
-			inside that function. */
+				mutex_exit(&block->mutex);
 
-			count += buf_flush_try_page(space, i, flush_type);
+				mutex_exit(&(buf_pool->mutex));
 
-			mutex_enter(&(buf_pool->mutex));
+				/* Note: as we release the buf_pool mutex
+				above, in buf_flush_try_page we cannot be sure
+				the page is still in a flushable state:
+				therefore we check it again inside that
+				function. */
+
+				count += buf_flush_try_page(space, i,
+							    flush_type);
+
+				mutex_enter(&(buf_pool->mutex));
+			} else {
+				mutex_exit(&block->mutex);
+			}
 		}
 	}
 
@@ -879,12 +906,15 @@ buf_flush_batch(
 		while ((block != NULL) && !found) {
 			ut_a(block->state == BUF_BLOCK_FILE_PAGE);
 
+			mutex_enter(&block->mutex);
+
 			if (buf_flush_ready_for_flush(block, flush_type)) {
 
 				found = TRUE;
 				space = block->space;
 				offset = block->offset;
 
+				mutex_exit(&block->mutex);
 				mutex_exit(&(buf_pool->mutex));
 
 				old_page_count = page_count;
@@ -901,10 +931,14 @@ buf_flush_batch(
 
 			} else if (flush_type == BUF_FLUSH_LRU) {
 
+				mutex_exit(&block->mutex);
+
 				block = UT_LIST_GET_PREV(LRU, block);
 			} else {
 				ut_ad(flush_type == BUF_FLUSH_LIST);
 
+				mutex_exit(&block->mutex);
+
 				block = UT_LIST_GET_PREV(flush_list, block);
 			}
 		}
@@ -986,10 +1020,14 @@ buf_flush_LRU_recommendation(void)
 		   + BUF_FLUSH_EXTRA_MARGIN)
 	       && (distance < BUF_LRU_FREE_SEARCH_LEN)) {
 
+		mutex_enter(&block->mutex);
+
 		if (buf_flush_ready_for_replace(block)) {
 			n_replaceable++;
 		}
 
+		mutex_exit(&block->mutex);
+
 		distance++;
 
 		block = UT_LIST_GET_PREV(LRU, block);
diff --git a/storage/innobase/buf/buf0lru.c b/storage/innobase/buf/buf0lru.c
index 4ebe94c40ec..377552ece6c 100644
--- a/storage/innobase/buf/buf0lru.c
+++ b/storage/innobase/buf/buf0lru.c
@@ -86,6 +86,11 @@ scan_again:
 	block = UT_LIST_GET_LAST(buf_pool->LRU);
 
 	while (block != NULL) {
+		buf_block_t*	prev_block;
+
+		mutex_enter(&block->mutex);
+		prev_block = UT_LIST_GET_PREV(LRU, block);
+
 		ut_a(block->state == BUF_BLOCK_FILE_PAGE);
 
 		if (block->space == id
@@ -112,6 +117,8 @@ scan_again:
 			if (block->is_hashed) {
 				page_no = block->offset;
 
+				mutex_exit(&block->mutex);
+
 				mutex_exit(&(buf_pool->mutex));
 
 				/* Note that the following call will acquire
@@ -138,7 +145,8 @@ scan_again:
 			buf_LRU_block_free_hashed_page(block);
 		}
 next_page:
-		block = UT_LIST_GET_PREV(LRU, block);
+		mutex_exit(&block->mutex);
+		block = prev_block;
 	}
 
 	mutex_exit(&(buf_pool->mutex));
@@ -211,6 +219,9 @@ buf_LRU_search_and_free_block(
 
 	while (block != NULL) {
 		ut_a(block->in_LRU_list);
+
+		mutex_enter(&block->mutex);
+
 		if (buf_flush_ready_for_replace(block)) {
 
 #ifdef UNIV_DEBUG
@@ -226,6 +237,7 @@ buf_LRU_search_and_free_block(
 			buf_LRU_block_remove_hashed_page(block);
 
 			mutex_exit(&(buf_pool->mutex));
+			mutex_exit(&block->mutex);
 
 			/* Remove possible adaptive hash index built on the
 			page; in the case of AWE the block may not have a
@@ -234,15 +246,21 @@ buf_LRU_search_and_free_block(
 			if (block->frame) {
 				btr_search_drop_page_hash_index(block->frame);
 			}
-			mutex_enter(&(buf_pool->mutex));
 
 			ut_a(block->buf_fix_count == 0);
 
+			mutex_enter(&(buf_pool->mutex));
+			mutex_enter(&block->mutex);
+
 			buf_LRU_block_free_hashed_page(block);
 			freed = TRUE;
+			mutex_exit(&block->mutex);
 
 			break;
 		}
+
+		mutex_exit(&block->mutex);
+
 		block = UT_LIST_GET_PREV(LRU, block);
 		distance++;
 
@@ -428,8 +446,12 @@ loop:
 			}
 		}
 
+		mutex_enter(&block->mutex);
+
 		block->state = BUF_BLOCK_READY_FOR_USE;
 
+		mutex_exit(&block->mutex);
+
 		mutex_exit(&(buf_pool->mutex));
 
 		if (started_monitor) {
@@ -838,6 +860,7 @@ buf_LRU_block_free_non_file_page(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&block->mutex));
 #endif /* UNIV_SYNC_DEBUG */
 	ut_ad(block);
 
@@ -877,6 +900,7 @@ buf_LRU_block_remove_hashed_page(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&block->mutex));
 #endif /* UNIV_SYNC_DEBUG */
 	ut_ad(block);
 
@@ -939,6 +963,7 @@ buf_LRU_block_free_hashed_page(
 {
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&(buf_pool->mutex)));
+	ut_ad(mutex_own(&block->mutex));
 #endif /* UNIV_SYNC_DEBUG */
 	ut_a(block->state == BUF_BLOCK_REMOVE_HASH);