Message-ID: <52E20A56.1000507@ti.com>
Date: Fri, 24 Jan 2014 01:38:14 -0500
From: Santosh Shilimkar <santosh.shilimkar@ti.com>
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To: Yinghai Lu <yinghai@kernel.org>
CC: Dave Hansen <dave.hansen@intel.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Ingo Molnar <mingo@elte.hu>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Linux-MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        Tejun Heo <tj@kernel.org>, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Panic on 8-node system in memblock_virt_alloc_try_nid()
References: <52E19C7D.7050603@intel.com> <CAE9FiQX9kTxnaqpWNgg3dUzr7+60YCrEx3q3xxO-G1n6z64xVQ@mail.gmail.com>
In-Reply-To: <CAE9FiQX9kTxnaqpWNgg3dUzr7+60YCrEx3q3xxO-G1n6z64xVQ@mail.gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org

Yinghai,

On Friday 24 January 2014 12:55 AM, Yinghai Lu wrote:
> On Thu, Jan 23, 2014 at 2:49 PM, Dave Hansen <dave.hansen@intel.com> wrote:
>> > Linus's current tree doesn't boot on an 8-node/1TB NUMA system that I
>> > have.  Its reboots are *LONG*, so I haven't fully bisected it, but it's
>> > down to a just a few commits, most of which are changes to the memblock
>> > code.  Since the panic is in the memblock code, it looks like a
>> > no-brainer.  It's almost certainly the code from Santosh or Grygorii
>> > that's triggering this.
>> >
>> > Config and good/bad dmesg with memblock=debug are here:
>> >
>> >         http://sr71.net/~dave/intel/3.13/
>> >
>> > Please let me know if you need it bisected further than this.
> Please check attached patch, and it should fix the problem.
> 

[...]

> 
> Subject: [PATCH] x86: Fix numa with reverting wrong memblock setting.
> 
> Dave reported Numa on x86 is broken on system with 1T memory.
> 
> It turns out
> | commit 5b6e529521d35e1bcaa0fe43456d1bbb335cae5d
> | Author: Santosh Shilimkar <santosh.shilimkar@ti.com>
> | Date:   Tue Jan 21 15:50:03 2014 -0800
> |
> |    x86: memblock: set current limit to max low memory address
> 
> set limit to low wrongly.
> 
> max_low_pfn_mapped is different from max_pfn_mapped.
> max_low_pfn_mapped is always under 4G.
> 
> That will memblock_alloc_nid all go under 4G.
> 
> Revert that offending patch.
> 
> Reported-by: Dave Hansen <dave.hansen@intel.com>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> 
>
This mostly will fix the $subject issue but the regression 
reported by Andrew [1] will surface with the revert. Its clear
now that even though commit fixed the issue, it wasn't the fix.

Would be great if you can have a look at the thread.

Regards,
Santosh

[1] http://lkml.indiana.edu/hypermail/linux/kernel/1312.1/03770.html
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