From: Dave Hansen <haveblue@us.ibm.com>
To: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, Eric Whitney <eric.whitney@hp.com>
Subject: Re: [PATCH 2.6.17-rc1-mm1] sched_domain-handle-kmalloc-failure-fix
Date: Fri, 07 Apr 2006 11:01:33 -0700 [thread overview]
Message-ID: <1144432893.24221.3.camel@localhost.localdomain> (raw)
In-Reply-To: <1144353528.5162.190.camel@localhost.localdomain>
On Thu, 2006-04-06 at 15:58 -0400, Lee Schermerhorn wrote:
> 2.6.17-rc1-mm1 hangs during boot on HP rx8620 and dl585 -- both 4 node
> NUMA platforms. Problem is in build_sched_domains() setting up the
> sched_group_nodes[] lists, resulting from patch:
> sched_domain-handle-kmalloc-failure.patch
>
> The referenced patch does not propagate the "next" pointer from the head
> of the list, resulting in a loop between the last 2 groups in the list.
> This causes a tight loop/hang in init_numa_sched_groups_power() because
> 'sg->next' never == 'group_head' when you have > 2 nodes.
Wow. I'm incredibly impressed that you tracked that down. I can't
believe how horribly unintelligible that code is.
I ran into the same freeze on a 4-node NUMA-Q. Your patch fixed it.
Is there any good reason that sched domains has to roll its own linked
lists? Why not use list_heads? Seems like it would avoid crappy
problems like this.
-- Dave
prev parent reply other threads:[~2006-04-07 18:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-06 19:58 [PATCH 2.6.17-rc1-mm1] sched_domain-handle-kmalloc-failure-fix Lee Schermerhorn
2006-04-07 18:01 ` Dave Hansen [this message]
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