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From: Boqun Feng <boqun.feng@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: peterz@infradead.org, mingo@kernel.org, tglx@linutronix.de,
	walken@google.com, kirill@shutemov.name,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	iamjoonsoo.kim@lge.com, akpm@linux-foundation.org,
	npiggin@gmail.com
Subject: Re: [PATCH v4 15/15] lockdep: Crossrelease feature documentation
Date: Wed, 18 Jan 2017 14:42:30 +0800	[thread overview]
Message-ID: <20170118064230.GF15084@tardis.cn.ibm.com> (raw)
In-Reply-To: <1481260331-360-16-git-send-email-byungchul.park@lge.com>

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On Fri, Dec 09, 2016 at 02:12:11PM +0900, Byungchul Park wrote:
[...]
> +Example 1:
> +
> +   CONTEXT X		   CONTEXT Y
> +   ---------		   ---------
> +   mutext_lock A
> +			   lock_page B
> +   lock_page B
> +			   mutext_lock A /* DEADLOCK */

s/mutext_lock/mutex_lock

> +   unlock_page B
> +			   mutext_unlock A
> +   mutex_unlock A
> +			   unlock_page B
> +
> +   where A is a lock class and B is a page lock.
> +
> +No, we cannot.
> +
> +Example 2:
> +
> +   CONTEXT X	   CONTEXT Y	   CONTEXT Z
> +   ---------	   ---------	   ----------
> +		   mutex_lock A
> +   lock_page B
> +		   lock_page B
> +				   mutext_lock A /* DEADLOCK */
> +				   mutext_unlock A

Ditto.

> +				   unlock_page B held by X
> +		   unlock_page B
> +		   mutex_unlock A
> +
> +   where A is a lock class and B is a page lock.
> +
> +No, we cannot.
> +
> +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().

Regards,
Boqun

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  parent reply	other threads:[~2017-01-18  6:42 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-09  5:11 [PATCH v4 00/15] lockdep: Implement crossrelease feature Byungchul Park
2016-12-09  5:11 ` [PATCH v4 01/15] x86/dumpstack: Optimize save_stack_trace Byungchul Park
2016-12-09  5:11 ` [PATCH v4 02/15] x86/dumpstack: Add save_stack_trace()_fast() Byungchul Park
2016-12-09  5:11 ` [PATCH v4 03/15] lockdep: Refactor lookup_chain_cache() Byungchul Park
2016-12-09  5:12 ` [PATCH v4 04/15] lockdep: Add a function building a chain between two classes Byungchul Park
2017-01-10 21:00   ` Peter Zijlstra
2017-01-12  1:41     ` Byungchul Park
2016-12-09  5:12 ` [PATCH v4 05/15] lockdep: Make check_prev_add can use a separate stack_trace Byungchul Park
2017-01-12 16:16   ` Peter Zijlstra
2017-01-13  2:45     ` Byungchul Park
2017-01-13  4:09     ` [PATCH] lockdep: Make a stack_trace instance passed to check_prev_add as an arg Byungchul Park
2017-01-13  4:38       ` Byungchul Park
2017-01-13 10:11     ` [PATCH v4 05/15] lockdep: Make check_prev_add can use a separate stack_trace Byungchul Park
2017-01-13 10:17       ` [PATCH 1/2] lockdep: Refactor save_trace() Byungchul Park
2017-01-13 10:17       ` [PATCH 2/2] lockdep: Pass a callback arg to check_prev_add() to handle stack_trace Byungchul Park
2017-01-17 15:54       ` [PATCH v4 05/15] lockdep: Make check_prev_add can use a separate stack_trace Peter Zijlstra
2017-01-18  2:04         ` Byungchul Park
2017-01-18 15:10           ` Peter Zijlstra
2017-01-19  2:47             ` Byungchul Park
2016-12-09  5:12 ` [PATCH v4 06/15] lockdep: Make save_trace can skip stack tracing of the current Byungchul Park
2017-01-12 16:37   ` Peter Zijlstra
2017-01-13  0:18     ` Byungchul Park
2016-12-09  5:12 ` [PATCH v4 07/15] lockdep: Implement crossrelease feature Byungchul Park
2017-01-13  4:39   ` Lai Jiangshan
2017-01-13  5:02     ` Byungchul Park
2017-01-16 15:10   ` Peter Zijlstra
2017-01-17  2:05     ` Byungchul Park
2017-01-17  7:12       ` Peter Zijlstra
2017-01-17  7:49         ` Byungchul Park
2017-01-17  7:14       ` Peter Zijlstra
2017-01-17  7:45         ` Byungchul Park
2017-01-16 15:13   ` Peter Zijlstra
2017-01-17  2:33     ` Byungchul Park
2017-01-17  6:24       ` Boqun Feng
2017-01-17  7:43         ` Byungchul Park
2016-12-09  5:12 ` [PATCH v4 08/15] lockdep: Make crossrelease use save_stack_trace_fast() Byungchul Park
2016-12-09  5:12 ` [PATCH v4 09/15] lockdep: Make print_circular_bug() crosslock-aware Byungchul Park
2016-12-09  5:12 ` [PATCH v4 10/15] lockdep: Apply crossrelease to completion operation Byungchul Park
2016-12-09  5:12 ` [PATCH v4 11/15] pagemap.h: Remove trailing white space Byungchul Park
2016-12-09  5:12 ` [PATCH v4 12/15] lockdep: Apply crossrelease to PG_locked lock Byungchul Park
2016-12-09  5:12 ` [PATCH v4 13/15] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2016-12-09  5:12 ` [PATCH v4 14/15] lockdep: Move data used in CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2016-12-09  5:12 ` [PATCH v4 15/15] lockdep: Crossrelease feature documentation Byungchul Park
2017-01-10 20:08   ` Peter Zijlstra
2017-01-11  1:29     ` Byungchul Park
2017-01-18  6:42   ` Boqun Feng [this message]
2017-01-18 10:53     ` Byungchul Park
2017-01-18 11:03       ` Peter Zijlstra
2017-01-18 11:54         ` Byungchul Park
2017-01-18 12:07           ` Peter Zijlstra
2017-01-18 12:14             ` byungchul.park
2017-01-18 14:12               ` Peter Zijlstra
2017-01-19  1:54                 ` Byungchul Park
2017-01-18 12:49             ` byungchul.park
2016-12-09  5:21 ` [FYI] Output of 'cat /proc/lockdep' after applying crossrelease Byungchul Park

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