Messages in this thread Patch in this message | | | Date | Mon, 25 May 2009 05:39:20 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 2.6.30-rc7] x86: remove remap percpu allocator for the time being |
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* Ingo Molnar <mingo@elte.hu> wrote:
> > @@ -365,9 +249,7 @@ void __init setup_per_cpu_areas(void) > > * of large page mappings. Please read comments on top of > > * each allocator for details. > > */ > > - ret = setup_pcpu_remap(static_size); > > - if (ret < 0) > > - ret = setup_pcpu_embed(static_size); > > + ret = setup_pcpu_embed(static_size); > > if (ret < 0) > > ret = setup_pcpu_4k(static_size); > > if (ret < 0) > > Please send a patch that only does the above chunk in essence. We > can deal with the rest in .31.
I've committed the minimal patch below.
Thanks,
Ingo
From 71c9d8b68b299bef614afc7907393564a9f1476f Mon Sep 17 00:00:00 2001 From: Tejun Heo <tj@kernel.org> Date: Mon, 25 May 2009 12:01:59 +0900 Subject: [PATCH] x86: Remove remap percpu allocator for the time being
Remap percpu allocator has subtle bug when combined with page attribute changing. Remap percpu allocator aliases PMD pages for the first chunk and as pageattr doesn't know about the alias it ends up updating page attributes of the original mapping thus leaving the alises in inconsistent state which might lead to subtle data corruption. Please read the following threads for more information:
http://thread.gmane.org/gmane.linux.kernel/835783
The following is the proposed fix which teaches pageattr about percpu aliases.
http://thread.gmane.org/gmane.linux.kernel/837157
However, the above changes are deemed too pervasive for upstream inclusion for 2.6.30 release, so this patch essentially disables the remap allocator for the time being.
Signed-off-by: Tejun Heo <tj@kernel.org> LKML-Reference: <4A1A0A27.4050301@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/kernel/setup_percpu.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c index 3a97a4c..8f0e13b 100644 --- a/arch/x86/kernel/setup_percpu.c +++ b/arch/x86/kernel/setup_percpu.c @@ -160,8 +160,10 @@ static ssize_t __init setup_pcpu_remap(size_t static_size) /* * If large page isn't supported, there's no benefit in doing * this. Also, on non-NUMA, embedding is better. + * + * NOTE: disabled for now. */ - if (!cpu_has_pse || !pcpu_need_numa()) + if (true || !cpu_has_pse || !pcpu_need_numa()) return -EINVAL; /*
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