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From: Christoph Lameter <christoph@lameter.com>
To: Ray Bryant <raybry@engr.sgi.com>
Cc: Ray Bryant <raybry@sgi.com>,
	Hirokazu Takahashi <taka@valinux.co.jp>, Andi Kleen <ak@suse.de>,
	Dave Hansen <haveblue@us.ibm.com>,
	Marcelo Tosatti <marcelo.tosatti@cyclades.com>,
	Christoph Hellwig <hch@infradead.org>,
	Ray Bryant <raybry@austin.rr.com>, linux-mm <linux-mm@kvack.org>,
	lhms-devel@lists.sourceforge.net, Paul Jackson <pj@sgi.com>,
	Nathan Scott <nathans@sgi.com>
Subject: Re: [Lhms-devel] Re: [PATCH 2.6.12-rc5 0/10] mm: manual page migration-rc3 -- overview
Date: Fri, 24 Jun 2005 08:41:05 -0700 (PDT)	[thread overview]
Message-ID: <Pine.LNX.4.62.0506240835020.9138@graphe.net> (raw)
In-Reply-To: <42BC1573.90201@engr.sgi.com>

On Fri, 24 Jun 2005, Ray Bryant wrote:

> In general, process flags are only updatable by the current process.
> There is no locking applied.  Having the migrating task set the PF_FREEZE
> bit in the migrated process runs the risk of losing the update to some other
> flags bit that is simultaneously set by the (running) migrated process.

Look at freeze_processes(). It takes a read lock on tasklist_lock. So if 
you take a write lock on tasklist lock then you could be safe that no 
other process sets PF_FREEZE while migrating.

Maybe we could downgrade that to a readlock if we would modify 
freeze_processes to to a test and test and use a test and set during migration.

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      reply	other threads:[~2005-06-24 15:41 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-22 16:39 [PATCH 2.6.12-rc5 0/10] mm: manual page migration-rc3 -- overview Ray Bryant
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 1/10] mm: hirokazu-steal_page_from_lru.patch Ray Bryant
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 2/10] mm: manual page migration-rc3 -- xfs-migrate-page-rc3.patch Ray Bryant
2005-06-22 17:30   ` [Lhms-devel] " Joel Schopp
2005-06-23  4:01   ` Nathan Scott
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 3/10] mm: manual page migration-rc3 -- add-node_map-arg-to-try_to_migrate_pages-rc3.patch Ray Bryant
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 4/10] mm: manual page migration-rc3 -- add-sys_migrate_pages-rc3.patch Ray Bryant
2005-06-22 17:23   ` Dave Hansen
2005-06-23  1:34     ` Ray Bryant
2005-06-23  1:42       ` Dave Hansen
2005-06-25 10:32   ` Hirokazu Takahashi
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 5/10] mm: manual page migration-rc3 -- sys_migrate_pages-mempolicy-migration-rc3.patch Ray Bryant
2005-06-23  1:51   ` Andi Kleen
2005-06-23 20:59     ` [Lhms-devel] " Ray Bryant
2005-06-23 21:05       ` Andi Kleen
2005-06-25  5:11         ` Ray Bryant
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 6/10] mm: manual page migration-rc3 -- add-mempolicy-control-rc3.patch Ray Bryant
2005-06-22 16:39 ` [PATCH 2.6.12-rc5 7/10] mm: manual page migration-rc3 -- sys_migrate_pages-migration-selection-rc3.patch Ray Bryant
2005-06-22 16:40 ` [PATCH 2.6.12-rc5 8/10] mm: manual page migration-rc3 -- sys_migrate_pages-cpuset-support-rc3.patch Ray Bryant
2005-06-22 16:40 ` [PATCH 2.6.12-rc5 9/10] mm: manual page migration-rc3 -- sys_migrate_pages-permissions-check-rc3.patch Ray Bryant
2005-06-22 16:40 ` [PATCH 2.6.12-rc5 10/10] mm: manual page migration-rc3 -- N1.2-add-nodemap-to-try_to_migrate_pages-call.patch Ray Bryant
2005-06-23 21:31 ` [PATCH 2.6.12-rc5 0/10] mm: manual page migration-rc3 -- overview Christoph Lameter
2005-06-23 23:00   ` Ray Bryant
2005-06-23 23:03     ` Christoph Lameter
2005-06-24 14:15   ` [Lhms-devel] " Ray Bryant
2005-06-24 15:41     ` Christoph Lameter [this message]

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