diff --git a/src/backend/storage/lmgr/deadlock.c b/src/backend/storage/lmgr/deadlock.c
index 5e49c78905..2d6a282d0a 100644
--- a/src/backend/storage/lmgr/deadlock.c
+++ b/src/backend/storage/lmgr/deadlock.c
@@ -214,7 +214,7 @@ InitDeadLockChecking(void)
  * and (b) we are typically invoked inside a signal handler.
  */
 DeadLockState
-DeadLockCheck(PGPROC *proc)
+DeadLockCheck(PGPROC *proc, bool readonly)
 {
 	int			i,
 				j;
@@ -245,6 +245,16 @@ DeadLockCheck(PGPROC *proc)
 		return DS_HARD_DEADLOCK;	/* cannot find a non-deadlocked state */
 	}
 
+	if (readonly)
+	{
+		if (nWaitOrders > 0)
+			return DS_SOFT_DEADLOCK;
+		else if (blocking_autovacuum_proc != NULL)
+			return DS_BLOCKED_BY_AUTOVACUUM;
+		else
+			return DS_NO_DEADLOCK;
+	}
+
 	/* Apply any needed rearrangements of wait queues */
 	for (i = 0; i < nWaitOrders; i++)
 	{
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 5f6727d501..a95bd99f8f 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -1665,6 +1665,7 @@ static void
 CheckDeadLock(void)
 {
 	int			i;
+	bool		shared = true;
 
 	/*
 	 * Acquire exclusive lock on the entire shared lock data structures. Must
@@ -1677,7 +1678,9 @@ CheckDeadLock(void)
 	 * interrupts.
 	 */
 	for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
-		LWLockAcquire(LockHashPartitionLockByIndex(i), LW_EXCLUSIVE);
+		LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
+
+retry:
 
 	/*
 	 * Check to see if we've been awoken by anyone in the interim.
@@ -1700,10 +1703,20 @@ CheckDeadLock(void)
 #endif
 
 	/* Run the deadlock check, and set deadlock_state for use by ProcSleep */
-	deadlock_state = DeadLockCheck(MyProc);
+	deadlock_state = DeadLockCheck(MyProc, shared);
 
 	if (deadlock_state == DS_HARD_DEADLOCK)
 	{
+		if (shared)
+		{
+			shared = false;
+			for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
+				LWLockRelease(LockHashPartitionLockByIndex(i));
+			for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
+				LWLockAcquire(LockHashPartitionLockByIndex(i), LW_EXCLUSIVE);
+			goto retry;
+		}
+
 		/*
 		 * Oops.  We have a deadlock.
 		 *
diff --git a/src/include/storage/lock.h b/src/include/storage/lock.h
index 765431e299..a501142059 100644
--- a/src/include/storage/lock.h
+++ b/src/include/storage/lock.h
@@ -564,7 +564,7 @@ extern void lock_twophase_postabort(TransactionId xid, uint16 info,
 extern void lock_twophase_standby_recover(TransactionId xid, uint16 info,
 							  void *recdata, uint32 len);
 
-extern DeadLockState DeadLockCheck(PGPROC *proc);
+extern DeadLockState DeadLockCheck(PGPROC *proc, bool readonly);
 extern PGPROC *GetBlockingAutoVacuumPgproc(void);
 extern void DeadLockReport(void) pg_attribute_noreturn();
 extern void RememberSimpleDeadLock(PGPROC *proc1,