linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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: Sun, 5 Mar 2017 17:01:09 +0900	[thread overview]
Message-ID: <20170305080109.GC11100@X58A-UD3R> (raw)
In-Reply-To: <20170302235003.GE28562@X58A-UD3R>

On Fri, Mar 03, 2017 at 08:50:03AM +0900, Byungchul Park wrote:
> 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..

I've thought it more and it seems not to be good. We could not use
subclass feature if we make page locks work with only one lockmap
instance. And there are several things we have to give up, that are,
things using each field in struct lockdep_map. So now, I'm not sure I
should change the current implementation. What do you think about it?

  reply	other threads:[~2017-03-05  8:01 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
2017-03-05  8:01             ` Byungchul Park [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170305080109.GC11100@X58A-UD3R \
    --to=byungchul.park@lge.com \
    --cc=akpm@linux-foundation.org \
    --cc=boqun.feng@gmail.com \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=kernel-team@lge.com \
    --cc=kirill@shutemov.name \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mingo@kernel.org \
    --cc=npiggin@gmail.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=walken@google.com \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).