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Date: Thu, 23 Jun 2016 20:12:16 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
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Subject: Re: [PATCH v3 00/13] Virtually mapped stacks with guard pages (x86,
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On 06/23, Linus Torvalds wrote:
>
> Ugh. Looking around at this, it turns out that a great example of this
> kind of legacy issue is the debug_mutex stuff.

Heh ;) I am looking at it too.

> It uses "struct thread_info *" as the owner pointer, and there is _no_
> existing reason for it. In fact, in every single place it actually
> wants the task_struct, and it does task_thread_info(task) just to
> convert it to the thread-info, and then converts it back with
> "ti->task".

Even worse, this task is always "current" afaics, so

> So the attached patch seems to be the right thing to do regardless of
> this whole discussion.

I think we should simply remove this argument.

And probably kill task_struct->blocked_on? I do not see the point of
this task->blocked_on != waiter check.

Oleg.