From: "Vegard Nossum" <vegard.nossum@gmail•com>
To: Mike Travis <travis@sgi•com>
Cc: Ingo Molnar <mingo@elte•hu>,
Andrew Morton <akpm@linux-foundation•org>,
Stephen Rothwell <sfr@canb•auug.org.au>,
linux-next@vger•kernel.org, LKML <linux-kernel@vger•kernel.org>
Subject: Re: linux-next: Tree for June 5
Date: Fri, 6 Jun 2008 16:07:09 +0200 [thread overview]
Message-ID: <19f34abd0806060707x7570c835u4b1837b54dfa36ba@mail.gmail.com> (raw)
In-Reply-To: <19f34abd0806060650q203bef48rd3b20c0cabec4774@mail.gmail.com>
On Fri, Jun 6, 2008 at 3:50 PM, Vegard Nossum <vegard.nossum@gmail•com> wrote:
> On Fri, Jun 6, 2008 at 3:33 PM, Mike Travis <travis@sgi•com> wrote:
>> Vegard Nossum wrote:
>>>
>>> I reproced it with gc 4.1.2. I think the error is somewhere in kernel/sched.c.
>>>
>>> static int __build_sched_domains(const cpumask_t *cpu_map,
>>> struct sched_domain_attr *attr)
>>> {
>>> ...
>>> for (i = 0; i < MAX_NUMNODES; i++) {
>>> ...
>>> sg = kmalloc_node(sizeof(struct sched_group), GFP_KERNEL, i);
>>> ...
>>>
>>> This code is calling into the allocator with a spurious value of i,
>>> which causes SLAB to use an index (of 4 in my case) that is out of
>>> bounds for its nodelist array (at least it hasn't been initialized).
>>>
>>> This bit of code (a bit further down, inside the same loop) is also dubious:
>>>
>>> sg = kmalloc_node(sizeof(struct sched_group),
>>> GFP_KERNEL, i);
>>> if (!sg) {
>>> printk(KERN_WARNING
>>> "Can not alloc domain group for node %d\n", j);
>>> goto error;
>>> }
>>>
>>> Where it passes i to kmalloc_node() but reports an allocation for node
>>> j. Which one is correct?
>>>
>
> Hm, I think I'm wrong and the code is correct. However...
>
>>> Hope this helps, will send an update if I find out more.
>>>
>>>
>>> Vegard
>>>
>>
>> Thanks Vegard for tracking this down. My thoughts were along the same
>> wavelength... ;-)
...
>
> This is a P4 3.0GHz with 1 physical CPU (but HT, so two logical CPUs).
> Yet node 4 is claimed to have a cpu too. That's bogus!
>
> (But I don't think it's an error in sched.c any more, probably the
> code that sets up the node maps.)
Aha.
The error is of course that the node masks for nodes > nr_node_ids are
not valid. While this function ignores that:
cpumask_t *_node_to_cpumask_ptr(int node)
{
if (node_to_cpumask_map == NULL) {
printk(KERN_WARNING
"_node_to_cpumask_ptr(%d): no node_to_cpumask_map!\n",
node);
dump_stack();
return &cpu_online_map;
}
return &node_to_cpumask_map[node];
}
EXPORT_SYMBOL(_node_to_cpumask_ptr);
Notice the return statement. It needs to check if node < nr_node_ids.
Vegard
--
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
-- E. W. Dijkstra, EWD1036
next prev parent reply other threads:[~2008-06-06 14:07 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-05 7:52 linux-next: Tree for June 5 Stephen Rothwell
2008-06-06 2:56 ` Andrew Morton
2008-06-06 3:46 ` Andrew Morton
2008-06-06 7:17 ` Ingo Molnar
2008-06-06 7:25 ` Ingo Molnar
2008-06-06 7:33 ` Andrew Morton
2008-06-06 7:41 ` Ingo Molnar
2008-06-06 7:47 ` Andrew Morton
2008-06-06 7:53 ` Stephen Rothwell
2008-06-06 8:01 ` Andrew Morton
2008-06-06 8:22 ` Stephen Rothwell
2008-06-06 8:30 ` Andrew Morton
2008-06-06 8:36 ` Ingo Molnar
2008-06-06 11:50 ` Paul Mackerras
2008-06-06 8:27 ` Ingo Molnar
2008-06-06 8:23 ` Ingo Molnar
2008-06-06 8:28 ` Stephen Rothwell
2008-06-06 8:33 ` Ingo Molnar
2008-06-06 8:38 ` Andrew Morton
2008-06-06 8:49 ` Ingo Molnar
2008-06-06 9:01 ` Andrew Morton
2008-06-06 10:47 ` Ingo Molnar
2008-06-06 16:37 ` Ingo Molnar
2008-06-06 7:29 ` Andrew Morton
2008-06-06 9:48 ` Andrew Morton
2008-06-06 9:54 ` Andrew Morton
2008-06-06 10:10 ` Ingo Molnar
2008-06-06 10:54 ` Andrew Morton
2008-06-06 11:21 ` Vegard Nossum
2008-06-06 11:57 ` Ingo Molnar
2008-06-06 12:33 ` Vegard Nossum
2008-06-06 13:33 ` Mike Travis
2008-06-06 13:50 ` Vegard Nossum
2008-06-06 14:07 ` Vegard Nossum [this message]
2008-06-06 14:20 ` Mike Travis
2008-06-06 14:36 ` Vegard Nossum
2008-06-06 14:41 ` Mike Travis
2008-06-06 14:51 ` Mike Travis
2008-06-06 14:54 ` Mike Travis
2008-06-06 14:57 ` Ingo Molnar
2008-06-06 15:01 ` Ingo Molnar
2008-06-06 15:13 ` Vegard Nossum
2008-06-06 15:23 ` Ingo Molnar
2008-06-06 15:52 ` Mike Travis
2008-06-18 8:26 ` Ingo Molnar
2008-06-06 15:04 ` Mike Travis
2008-06-06 15:20 ` Mike Travis
2008-06-06 15:33 ` Ingo Molnar
2008-06-06 15:13 ` Ingo Molnar
2008-06-06 14:13 ` Mike Travis
2008-06-06 13:28 ` Mike Travis
2008-06-06 17:15 ` Ingo Molnar
2008-06-06 7:33 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2009-06-05 6:41 Stephen Rothwell
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