From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Christoph Lameter <clameter@engr.sgi.com>
Cc: Nick Piggin <npiggin@suse.de>, Andrew Morton <akpm@osdl.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: Race in new page migration code?
Date: Sun, 15 Jan 2006 16:28:56 +1100 [thread overview]
Message-ID: <43C9DD98.5000506@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.62.0601141040400.11601@schroedinger.engr.sgi.com>
Christoph Lameter wrote:
> On Sat, 14 Jan 2006, Nick Piggin wrote:
>
>
>>>We take that reference count on the page:
>>
>>Yes, after you have dropped all your claims to pin this page
>>(ie. pte lock). You really can't take a refcount on a page that
>
>
> Oh. Now I see. I screwed that up by a fix I added.... We cannot drop the
> ptl here. So back to the way it was before. Remove the draining from
> isolate_lru_page and do it before scanning for pages so that we do not
> have to drop the ptl.
>
OK (either way is fine), but you should still drop the __isolate_lru_page
nonsense and revert it like my patch does.
> Also remove the WARN_ON since its now even possible that other actions of
> the VM move the pages into the LRU lists while we scan for pages to
> migrate.
>
Well, it has always been possible since vmscan started batching scans a
long time ago. Actually seeing as you only take a read lock on the semaphore
it is probably also possible to have a concurrent migrate operation cause
this as well.
Thanks,
Nick
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-01-15 5:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-14 15:55 Race in new page migration code? Nick Piggin
2006-01-14 18:01 ` Christoph Lameter
2006-01-14 18:19 ` Nick Piggin
2006-01-14 18:58 ` Christoph Lameter
2006-01-15 5:28 ` Nick Piggin [this message]
2006-01-16 6:54 ` Christoph Lameter
2006-01-16 7:44 ` Nick Piggin
2006-01-17 8:29 ` Magnus Damm
2006-01-17 9:01 ` Nick Piggin
2006-01-17 9:22 ` Magnus Damm
2006-01-15 6:58 ` Nick Piggin
2006-01-15 10:58 ` Hugh Dickins
2006-01-16 6:51 ` Christoph Lameter
2006-01-16 12:32 ` Hugh Dickins
2006-01-16 15:47 ` Christoph Lameter
2006-01-16 16:06 ` Hugh Dickins
2006-01-16 16:10 ` Christoph Lameter
2006-01-16 16:28 ` Hugh Dickins
2006-01-16 16:51 ` Andi Kleen
2006-01-16 16:56 ` Nick Piggin
2006-01-17 5:06 ` Christoph Lameter
2006-01-17 11:16 ` Nick Piggin
2006-01-17 17:29 ` Christoph Lameter
2006-01-17 18:46 ` Lee Schermerhorn
2006-01-17 18:48 ` Christoph Lameter
2006-01-17 19:01 ` Hugh Dickins
2006-01-17 20:15 ` Christoph Lameter
2006-01-17 20:49 ` Hugh Dickins
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