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From: Byungchul Park <byungchul.park@lge.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "'Peter Zijlstra'" <peterz@infradead.org>, <mingo@kernel.org>,
	<tglx@linutronix.de>, <walken@google.com>, <boqun.feng@gmail.com>,
	<kirill@shutemov.name>, <linux-kernel@vger.kernel.org>,
	<linux-mm@kvack.org>, <iamjoonsoo.kim@lge.com>,
	<akpm@linux-foundation.org>, <npiggin@gmail.com>,
	<kernel-team@lge.com>
Subject: Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature
Date: Fri, 3 Mar 2017 08:50:03 +0900	[thread overview]
Message-ID: <20170302235003.GE28562@X58A-UD3R> (raw)
In-Reply-To: <20170302143949.GP16328@bombadil.infradead.org>

On Thu, Mar 02, 2017 at 06:39:49AM -0800, Matthew Wilcox wrote:
> On Thu, Mar 02, 2017 at 01:45:35PM +0900, byungchul.park wrote:
> > From: Matthew Wilcox [mailto:willy@infradead.org]
> > > On Tue, Feb 28, 2017 at 07:15:47PM +0100, Peter Zijlstra wrote:
> > > > (And we should not be returning to userspace with locks held anyway --
> > > > lockdep already has a check for that).
> > > 
> > > Don't we return to userspace with page locks held, eg during async
> > > directio?
> > 
> > Hello,
> > 
> > I think that the check when returning to user with crosslocks held
> > should be an exception. Don't you think so?
> 
> Oh yes.  We have to keep the pages locked during reads, and we have to
> return to userspace before I/O is complete, therefore we have to return
> to userspace with pages locked.  They'll be unlocked by the interrupt
> handler in page_endio().

Agree.

> Speaking of which ... this feature is far too heavy for use in production
> on pages.  You're almost trebling the size of struct page.  Can we
> do something like make all struct pages share the same lockdep_map?
> We'd have to not complain about holding one crossdep lock and acquiring
> another one of the same type, but with millions of pages in the system,
> it must surely be creating a gargantuan graph right now?

Um.. I will try it for page locks to work with one lockmap. That is also
what Peterz pointed out and what I worried about when implementing..

Thanks for your opinion.

  reply	other threads:[~2017-03-02 23:51 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-18 13:17 [PATCH v5 00/13] lockdep: Implement crossrelease feature Byungchul Park
2017-01-18 13:17 ` [PATCH v5 01/13] lockdep: Refactor lookup_chain_cache() Byungchul Park
2017-01-19  9:16   ` Boqun Feng
2017-01-19  9:52     ` Byungchul Park
2017-01-26  7:53     ` Byungchul Park
2017-01-18 13:17 ` [PATCH v5 02/13] lockdep: Fix wrong condition to print bug msgs for MAX_LOCKDEP_CHAIN_HLOCKS Byungchul Park
2017-01-18 13:17 ` [PATCH v5 03/13] lockdep: Add a function building a chain between two classes Byungchul Park
2017-01-18 13:17 ` [PATCH v5 04/13] lockdep: Refactor save_trace() Byungchul Park
2017-01-18 13:17 ` [PATCH v5 05/13] lockdep: Pass a callback arg to check_prev_add() to handle stack_trace Byungchul Park
2017-01-26  7:43   ` Byungchul Park
2017-01-18 13:17 ` [PATCH v5 06/13] lockdep: Implement crossrelease feature Byungchul Park
2017-02-28 12:26   ` Peter Zijlstra
2017-02-28 12:45   ` Peter Zijlstra
2017-02-28 12:49     ` Peter Zijlstra
2017-03-01  6:20       ` Byungchul Park
2017-02-28 13:05   ` Peter Zijlstra
2017-02-28 13:28     ` Byungchul Park
2017-02-28 13:35       ` Peter Zijlstra
2017-02-28 14:00         ` Byungchul Park
2017-02-28 13:10   ` Peter Zijlstra
2017-02-28 13:24     ` Byungchul Park
2017-02-28 18:29       ` Peter Zijlstra
2017-03-01  4:40         ` Byungchul Park
2017-03-01 10:45           ` Peter Zijlstra
2017-03-01 12:10             ` Byungchul Park
2017-02-28 13:40   ` Peter Zijlstra
2017-03-01  5:43     ` Byungchul Park
2017-03-01 12:28       ` Peter Zijlstra
2017-03-02 13:40         ` Peter Zijlstra
2017-03-03  0:17           ` Byungchul Park
2017-03-03  8:14             ` Peter Zijlstra
2017-03-03  9:13               ` Peter Zijlstra
2017-03-03  9:32                 ` Peter Zijlstra
2017-03-05  3:33                 ` Byungchul Park
2017-08-10 12:18                 ` [tip:locking/core] locking/lockdep: Avoid creating redundant links tip-bot for Peter Zijlstra
2017-03-05  3:08               ` [PATCH v5 06/13] lockdep: Implement crossrelease feature Byungchul Park
2017-03-07 11:42                 ` Peter Zijlstra
2017-03-03  0:39           ` Byungchul Park
2017-02-28 15:49   ` Peter Zijlstra
2017-03-01  5:17     ` Byungchul Park
2017-03-01  6:18       ` Byungchul Park
2017-03-02  2:52       ` Byungchul Park
2017-02-28 18:15   ` Peter Zijlstra
2017-03-01  7:21     ` Byungchul Park
2017-03-01 10:43       ` Peter Zijlstra
2017-03-01 12:27         ` Byungchul Park
2017-03-02  4:20     ` Matthew Wilcox
2017-03-02  4:45       ` byungchul.park
2017-03-02 14:39         ` Matthew Wilcox
2017-03-02 23:50           ` Byungchul Park [this message]
2017-03-05  8:01             ` Byungchul Park
2017-03-14  7:36     ` Byungchul Park
2017-03-02 13:41   ` Peter Zijlstra
2017-03-02 23:43     ` Byungchul Park
2017-01-18 13:17 ` [PATCH v5 07/13] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park
2017-01-18 13:17 ` [PATCH v5 08/13] lockdep: Apply crossrelease to completions Byungchul Park
2017-01-18 13:17 ` [PATCH v5 09/13] pagemap.h: Remove trailing white space Byungchul Park
2017-01-18 13:17 ` [PATCH v5 10/13] lockdep: Apply crossrelease to PG_locked locks Byungchul Park
2017-01-18 13:17 ` [PATCH v5 11/13] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park
2017-01-18 13:17 ` [PATCH v5 12/13] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park
2017-01-18 13:17 ` [PATCH v5 13/13] lockdep: Crossrelease feature documentation Byungchul Park
2017-01-20  9:08   ` [REVISED DOCUMENT] " Byungchul Park
2017-02-20  8:38 ` [PATCH v5 00/13] lockdep: Implement crossrelease feature Byungchul Park

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