From: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux-foundation.org>
Cc: Tony Vroon <tony@linx.net>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] percpu: fix unit_map[] verification in pcpu_setup_first_chunk()
Date: Tue, 29 Sep 2009 01:35:36 +0900 [thread overview]
Message-ID: <4AC0E5D8.6090707@kernel.org> (raw)
In-Reply-To: <alpine.DEB.1.10.0909281223510.16040@gentwo.org>
Christoph Lameter wrote:
> On Tue, 29 Sep 2009, Tejun Heo wrote:
>
>> pcpu_setup_first_chunk() incorrectly used NR_CPUS as the impossible
>> unit number while unit number can equal and go over NR_CPUS with
>> sparse unit map. This triggers BUG_ON() spuriously on machines which
>> have non-power-of-two number of cpus. Use UINT_MAX instead.
>
> Uhhh. Funky. The assumption nr_cpu_ids < NR_CPUS has been broken. Wonder
> what other effects that will have. In particular since the slab and page
> allocators have arrays indexed by the cpu number and those arrays are
> dimensioned for NR_CPUS.
Heh.. that's not what's broken. unit# can legally go over NR_CPUS or
nr_cpu_ids as cpus can be sparsely mapped to units. The problem is
that I didn't fix unit_map allocation. Will update the patch. Just a
sec.
--
tejun
next prev parent reply other threads:[~2009-09-28 16:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-24 0:53 [PATCH] percpu: make pcpu_setup_first_chunk() failures more verbose Tejun Heo
2009-09-24 12:49 ` [PATCH] percpu: make allocation " Tejun Heo
2009-09-27 12:49 ` 2.6.31-09194-g0d9df25 Early boot exception Tony Vroon
2009-09-28 16:19 ` [PATCH] percpu: fix unit_map[] verification in pcpu_setup_first_chunk() Tejun Heo
2009-09-28 16:25 ` Christoph Lameter
2009-09-28 16:35 ` Tejun Heo [this message]
2009-09-28 16:38 ` Tejun Heo
2009-09-28 16:40 ` Christoph Lameter
2009-09-28 16:53 ` Tejun Heo
2009-09-28 22:07 ` Tony Vroon
2009-09-29 0:15 ` Tejun Heo
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