From: "David S. Miller" <davem@davemloft.net>
To: davidm@hpl.hp.com
Cc: davidm@napali.hpl.hp.com, mingo@elte.hu, tony.luck@intel.com,
linux-kernel@vger.kernel.org
Subject: Re: [patch] sched: unlocked context-switches
Date: Sat, 9 Apr 2005 15:58:10 -0700 [thread overview]
Message-ID: <20050409155810.593d8f7b.davem@davemloft.net> (raw)
In-Reply-To: <16983.33049.962002.335198@napali.hpl.hp.com>
On Sat, 9 Apr 2005 00:15:37 -0700
David Mosberger <davidm@napali.hpl.hp.com> wrote:
> Yes, of course. The deadlock was due to context-switching, not
> switch_mm() per se. Hopefully someone else beats me to remembering
> the details before Monday.
Sparc64 has a deadlock because we hold mm->page_table_lock during
switch_mm(). I bet IA64 did something similar, as I remember it
had a very similar locking issue in this area.
So the deadlock was, we held the runqueue locks over switch_mm(),
switch_mm() spins on mm->page_table_lock, the cpu which does have
mm->page_table_lock tries to do a wakeup on the first cpu's runqueue.
Classic AB-BA deadlock.
next prev parent reply other threads:[~2005-04-09 23:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3R6Ir-89Y-23@gated-at.bofh.it>
2005-04-09 6:32 ` [patch] sched: unlocked context-switches David Mosberger-Tang
2005-04-09 7:07 ` Ingo Molnar
2005-04-09 7:15 ` David Mosberger
2005-04-09 22:58 ` David S. Miller [this message]
2005-04-10 6:43 ` Ingo Molnar
2005-04-12 1:06 ` David Mosberger
2005-04-12 2:12 ` Nick Piggin
2005-04-12 17:14 ` David Mosberger
2005-04-13 3:26 ` Nick Piggin
2005-04-12 6:42 ` Ingo Molnar
2005-04-12 17:15 ` David Mosberger
2005-04-08 18:38 Luck, Tony
2005-04-09 4:38 ` Ingo Molnar
2005-04-09 6:28 ` Nick Piggin
2005-04-09 6:55 ` Ingo Molnar
2005-04-09 7:11 ` Nick Piggin
2005-04-09 9:22 ` Benjamin Herrenschmidt
2005-04-09 22:46 ` David S. Miller
2005-04-10 7:23 ` Richard Henderson
-- strict thread matches above, loose matches on Subject: below --
2005-04-08 12:16 Ingo Molnar
2005-04-29 9:09 ` Andrew Morton
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