From: Andrea Arcangeli <andrea@qumranet.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Robin Holt <holt@sgi.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
kvm-devel@lists.sourceforge.net,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
general@lists.openfabrics.org, steiner@sgi.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch 02/10] emm: notifier logic
Date: Sat, 5 Apr 2008 02:57:59 +0200 [thread overview]
Message-ID: <20080405005759.GH14784@duo.random> (raw)
In-Reply-To: <20080404223131.469710551@sgi.com>
On Fri, Apr 04, 2008 at 03:30:50PM -0700, Christoph Lameter wrote:
> + mm_lock(mm);
> + e->next = mm->emm_notifier;
> + /*
> + * The update to emm_notifier (e->next) must be visible
> + * before the pointer becomes visible.
> + * rcu_assign_pointer() does exactly what we need.
> + */
> + rcu_assign_pointer(mm->emm_notifier, e);
> + mm_unlock(mm);
My mm_lock solution makes all rcu serialization an unnecessary
overhead so you should remove it like I already did in #v11. If it
wasn't the case, then mm_lock wouldn't be a definitive fix for the
race.
> + e = rcu_dereference(e->next);
Same here.
WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <andrea@qumranet.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
kvm-devel@lists.sourceforge.net, steiner@sgi.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Robin Holt <holt@sgi.com>,
general@lists.openfabrics.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [ofa-general] Re: [patch 02/10] emm: notifier logic
Date: Sat, 5 Apr 2008 02:57:59 +0200 [thread overview]
Message-ID: <20080405005759.GH14784@duo.random> (raw)
In-Reply-To: <20080404223131.469710551@sgi.com>
On Fri, Apr 04, 2008 at 03:30:50PM -0700, Christoph Lameter wrote:
> + mm_lock(mm);
> + e->next = mm->emm_notifier;
> + /*
> + * The update to emm_notifier (e->next) must be visible
> + * before the pointer becomes visible.
> + * rcu_assign_pointer() does exactly what we need.
> + */
> + rcu_assign_pointer(mm->emm_notifier, e);
> + mm_unlock(mm);
My mm_lock solution makes all rcu serialization an unnecessary
overhead so you should remove it like I already did in #v11. If it
wasn't the case, then mm_lock wouldn't be a definitive fix for the
race.
> + e = rcu_dereference(e->next);
Same here.
next prev parent reply other threads:[~2008-04-05 0:58 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-04 22:30 [patch 00/10] [RFC] EMM Notifier V3 Christoph Lameter
2008-04-04 22:30 ` [ofa-general] " Christoph Lameter
2008-04-04 22:30 ` [patch 01/10] emm: mm_lock: Lock a process against reclaim Christoph Lameter
2008-04-04 22:30 ` [ofa-general] " Christoph Lameter
2008-04-04 23:12 ` Jeremy Fitzhardinge
2008-04-04 23:12 ` [ofa-general] " Jeremy Fitzhardinge
2008-04-05 0:41 ` Andrea Arcangeli
2008-04-05 0:41 ` [ofa-general] " Andrea Arcangeli
2008-04-07 13:55 ` Peter Zijlstra
2008-04-07 13:55 ` [ofa-general] " Peter Zijlstra
2008-04-07 19:02 ` Jeremy Fitzhardinge
2008-04-07 19:02 ` [ofa-general] " Jeremy Fitzhardinge
2008-04-07 19:35 ` Andrea Arcangeli
2008-04-07 19:35 ` [ofa-general] " Andrea Arcangeli
2008-04-04 22:30 ` [patch 02/10] emm: notifier logic Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-05 0:57 ` Andrea Arcangeli [this message]
2008-04-05 0:57 ` [ofa-general] " Andrea Arcangeli
2008-04-07 5:48 ` Christoph Lameter
2008-04-07 5:48 ` [ofa-general] " Christoph Lameter
2008-04-07 6:06 ` Andrea Arcangeli
2008-04-07 6:06 ` Andrea Arcangeli
2008-04-07 6:20 ` Christoph Lameter
2008-04-07 6:20 ` Christoph Lameter
2008-04-07 7:13 ` Andrea Arcangeli
2008-04-07 7:13 ` [ofa-general] " Andrea Arcangeli
2008-04-08 20:23 ` Christoph Lameter
2008-04-08 20:23 ` Christoph Lameter
2008-04-08 20:23 ` [ofa-general] " Christoph Lameter
2008-04-09 14:29 ` Andrea Arcangeli
2008-04-09 14:29 ` Andrea Arcangeli
2008-04-09 14:29 ` [ofa-general] " Andrea Arcangeli
2008-04-04 22:30 ` [patch 03/10] emm: Move tlb flushing into free_pgtables Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-04 22:30 ` [patch 04/10] emm: Convert i_mmap_lock to i_mmap_sem Christoph Lameter
2008-04-04 22:30 ` [ofa-general] " Christoph Lameter
2008-04-04 22:30 ` [patch 05/10] emm: Remove tlb pointer from the parameters of unmap vmas Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-04 22:30 ` [patch 06/10] emm: Convert anon_vma lock to rw_sem and refcount Christoph Lameter
2008-04-04 22:30 ` [ofa-general] " Christoph Lameter
2008-04-04 22:30 ` [patch 07/10] xpmem: This patch exports zap_page_range as it is needed by XPMEM Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-04 22:30 ` [patch 08/10] xpmem: Locking rules for taking multiple mmap_sem locks Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-04 22:30 ` [patch 09/10] xpmem: The device driver Christoph Lameter
2008-04-04 22:30 ` Christoph Lameter
2008-04-04 22:30 ` [patch 10/10] xpmem: Simple example Christoph Lameter
2008-04-04 22:30 ` [ofa-general] " Christoph Lameter
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=20080405005759.GH14784@duo.random \
--to=andrea@qumranet.com \
--cc=a.p.zijlstra@chello.nl \
--cc=clameter@sgi.com \
--cc=general@lists.openfabrics.org \
--cc=holt@sgi.com \
--cc=kvm-devel@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=steiner@sgi.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.