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From: "Vegard Nossum" <vegard.nossum@gmail•com>
To: Ingo Molnar <mingo@elte•hu>
Cc: Andrew Morton <akpm@linux-foundation•org>,
	Stephen Rothwell <sfr@canb•auug.org.au>,
	linux-next@vger•kernel.org, LKML <linux-kernel@vger•kernel.org>,
	Mike Travis <travis@sgi•com>
Subject: Re: linux-next: Tree for June 5
Date: Fri, 6 Jun 2008 14:33:56 +0200	[thread overview]
Message-ID: <19f34abd0806060533x6d3ff66tc29306143103fc40@mail.gmail.com> (raw)
In-Reply-To: <20080606115759.GA29321@elte.hu>

On Fri, Jun 6, 2008 at 1:57 PM, Ingo Molnar <mingo@elte•hu> wrote:
>
> * Andrew Morton <akpm@linux-foundation•org> wrote:
>
>> Good
>>
>>       a9ad585c8a18f7ba754b85f5786976609b9d7d29
>>       Author: Mike Travis <travis@sgi•com>  2008-05-12 12:21:12
>>       Committer: Thomas Gleixner <tglx@linutronix•de>  2008-05-23 09:07:47
>>       Parent: 543e21916497be5a4005fd5820264ce1de9bd56d (x86: restore pda nodenumber field)
>>       Child:  78d49c6d890aee9cf8aea371011c9d7b0121b822 (x86: remove static boot_cpu_pda array v2)
>>       Branch:
>>       Follows: v2.6.26-rc2
>>       Precedes: next-20080526
>>
>>           x86: remove the static 256k node_to_cpumask_map
>>
>> crash, as described earlier.
>
> thanks for tracking it down! This was the origin of the commit:
>
>  # tip/x86/numa: a9ad585: x86: remove the static 256k node_to_cpumask_map
>
> which has been in -tip since May 12 and in linux-next for two weeks
> AFAICS, which is beyond the point of being something freshly wrong.
>
> So i suspect something more subtle here. What compiler version are you
> using? This crash is not something that has been found in testing before
> - i use rather new compilers, gcc 4.2.2 most of the time. Previous
> compilers miscompile the kernel seriously so it's not usable for our
> regression testing grid.
>

Hi,

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?

Hope this helps, will send an update if I find out more.


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

  reply	other threads:[~2008-06-06 12:34 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 [this message]
2008-06-06 13:33               ` Mike Travis
2008-06-06 13:50                 ` Vegard Nossum
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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