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Date: Sun, 12 Apr 2015 20:38:39 +0200
Message-ID: <CAFHCsPVDiRnzwXHG-6YoZgsYCo5mysv3RswqVVtqSy6J2EZNwQ@mail.gmail.com>
Subject: Re: [patch] deadlock in vm_reserv_reclaim_contig()
From: Svatopluk Kraus <onwahe@gmail.com>
To: Alan Cox <alc@rice.edu>
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On Sat, Apr 11, 2015 at 7:57 PM, Alan Cox <alc@rice.edu> wrote:
> On 04/10/2015 04:11, Svatopluk Kraus wrote:
>> Hi,
>>
>> my RPI-B has been stuck in vm_reserv_reclaim_contig() due to a bug
>> within that function. I can reproduce that easily on my two-core
>> pandaboard when I limit all memory in system to 128MiB and run "make
>> -j16 kernel-toolchain". It happens in few seconds.
>>
>> The patch should be self-explanatory. The problem is that there is a
>> free page found in reservation which does not fulfill alignment
>> requirement, thus next free page should be looked for. However, due to
>> the bug, the same free page is found out again and again.
>>
>> The patch takes into account that shift by m on n-bit arch has an
>> undefined behaviour if m >= n.
>>
>
> The patch looks correct.  I'm just going to tweak the comment, and then
> I'll commit it.
>

Thank you.
Svatopluk Kraus