Re: v2.6.26-rc7: BUG: unable to handle kernel NULL pointer dereference

Rusty Russell wrote:
On Monday 23 June 2008 02:29:07 Vegard Nossum wrote:
And the (cpu < nr_cpu_ids) fails because the CPU has just been
offlined (or failed to initialize, but it's the same thing), while
NR_CPUS is the value that was compiled in as CONFIG_NR_CPUS (so the
former check will always be true).

I don't think it is valid to ask for a per_cpu() variable on a CPU
which does not exist, though

Yes it is. As long as cpu_possible(cpu), per_cpu(cpu) is valid.

The number check should be removed: checking cpu_possible() is sufficient.

Hope that helps,
Rusty.

I don't see a check for index being out of range in cpu_possible().

Thanks,
Mike
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Relevant Pages

  • Re: [PATCH] tty: export get_current_tty
    ... Initialize the console device. ... More majordomo info at http://vger.kernel.org/majordomo-info.html ... Please read the FAQ at http://www.tux.org/lkml/ ...
    (Linux-Kernel)
  • Re: [ath5k-devel] [PATCH 1/1] ath5k: fix hw rate index condition
    ... this by checking earlier for the error or simply assigning it an actual ... I guess an alternative is to initialize to 0, ... More majordomo info at http://vger.kernel.org/majordomo-info.html ... Please read the FAQ at http://www.tux.org/lkml/ ...
    (Linux-Kernel)
  • Re: [PATCH 6/8] param: use free hook for charp
    ... Rusty Russell wrote: ... Instead of using a "I kmalloced this" flag, we keep track of the kmalloced ... More majordomo info at http://vger.kernel.org/majordomo-info.html ... Please read the FAQ at http://www.tux.org/lkml/ ...
    (Linux-Kernel)
  • *sigh* /proc/*/pagemap
    ... I'm few days from my patch-sending facility, ... initialize pagemap_walk.mm to "mm", so the code starts working as ... More majordomo info at http://vger.kernel.org/majordomo-info.html ... Please read the FAQ at http://www.tux.org/lkml/ ...
    (Linux-Kernel)
  • Re: [PATCH 8/8] Convert PDA into the percpu section
    ... Rusty Russell wrote: ... Why testing with qemu is not enough. ... More majordomo info at http://vger.kernel.org/majordomo-info.html ... Please read the FAQ at http://www.tux.org/lkml/ ...
    (Linux-Kernel)