Hi Andrew,

On Fri, 21 Jan 2011 15:31:54 -0800
Andrew Morton [off-list ref] wrote:

On Fri, 21 Jan 2011 15:34:31 +0900
Toshiyuki Okajima [off-list ref] wrote:

quoted

Hi.

I executed fsstress and then found that the system hung up.
At that time, I took the crash dump. Here is the backtrace of the process
which causes this hangup.

[long description]

--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c

@@ -736,10 +736,11 @@ next:
 		}
 	}
 	/*
-	 * The iftag must have been set somewhere because otherwise
-	 * we would return immediated at the beginning of the function
+	 * We need not to tag the root tag if there is no tag which is set with
+	 * settag within the range from *first_indexp to last_index.
 	 */
-	root_tag_set(root, settag);
+	if (tagged > 0)
+		root_tag_set(root, settag);
 	*first_indexp = index;
 
 	return tagged;

Thanks.

It should be fairly simple to reproduce this hang with the userspace
test harness (http://userweb.kernel.org/~akpm/stuff/rtth.tar.gz) and to
then demonstrate that the fix fixes it.

If you have time, could you please do that and then send the rtth
updates to me?

I add regression2_test for this bug into your testset (rtth.tar.gz).
This is originated from regression1_test.

Regards,
Toshiyuki Okajima