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 15:50:01 +0200 [thread overview]
Message-ID: <19f34abd0806060650q203bef48rd3b20c0cabec4774@mail.gmail.com> (raw)
In-Reply-To: <48493CBD.1000202@sgi.com>
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... ;-)
I applied this patch
@@ -7133,6 +7133,14 @@ static int __build_sched_domains(const
cpumask_t *cpu_map,
cpus_clear(*covered);
cpus_and(*nodemask, *nodemask, *cpu_map);
+
+ printk("node %d\n", i);
+ for (j = 0; j < NR_CPUS; ++j)
+ printk("%c", cpu_isset(j, *nodemask) ? 'X' : '.');
+ printk("\n");
+
+ printk("empty = %d\n", cpus_empty(*nodemask));
+
if (cpus_empty(*nodemask)) {
sched_group_nodes[i] = NULL;
continue;
and it shows some really strange output, maybe it makes sense to you:
(the X means cpu is in the node)
Total of 2 processors activated (11976.24 BogoMIPS).
node 0
XX..............................................................................
................................................................................
................................................................................
...............
empty = 0
node 1
XX..............................................................................
................................................................................
................................................................................
...............
empty = 0
l3 = cachep->nodelists[0] (size-64) = ffff81003f824340
node 2
................................................................................
................................................................................
................................................................................
...............
empty = 1
node 3
................................................................................
................................................................................
................................................................................
...............
empty = 1
node 4
X...............................................................................
................................................................................
................................................................................
...............
empty = 0
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.)
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 13:50 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 [this message]
2008-06-06 14:07 ` Vegard Nossum
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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