On Wed, Jan 18, 2017 at 08:54:28PM +0900, Byungchul Park wrote:

On Wed, Jan 18, 2017 at 12:03:17PM +0100, Peter Zijlstra wrote:

quoted

On Wed, Jan 18, 2017 at 07:53:47PM +0900, Byungchul Park wrote:

quoted

On Wed, Jan 18, 2017 at 02:42:30PM +0800, Boqun Feng wrote:

quoted

On Fri, Dec 09, 2016 at 02:12:11PM +0900, Byungchul Park wrote:
[...]

quoted

+Example 1:
+
+   CONTEXT X		   CONTEXT Y
+   ---------		   ---------
+   mutext_lock A
+			   lock_page B
+   lock_page B
+			   mutext_lock A /* DEADLOCK */

s/mutext_lock/mutex_lock

Thank you.

quoted

quoted

+Example 3:
+
+   CONTEXT X		   CONTEXT Y
+   ---------		   ---------
+			   mutex_lock A
+   mutex_lock A
+   mutex_unlock A
+			   wait_for_complete B /* DEADLOCK */

I think this part better be:

   CONTEXT X		   CONTEXT Y
   ---------		   ---------
   			   mutex_lock A
   mutex_lock A
   			   wait_for_complete B /* DEADLOCK */
   mutex_unlock A

, right? Because Y triggers DEADLOCK before X could run mutex_unlock().

There's no different between two examples.

There is..

quoted

No matter which one is chosen, mutex_lock A in CONTEXT X cannot be passed.

But your version shows it does mutex_unlock() before CONTEXT Y does
wait_for_completion().

The thing about these diagrams is that both columns are assumed to have
the same timeline.

X cannot acquire mutex A because Y already acquired it.

In order words, all statements below mutex_lock A in X cannot run.

But your timeline shows it does, which is the error that Boqun pointed
out.

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