RE: Commenting out out_of_memory() function in __alloc_pages()

Abu M. Muttalib
2006-07-09T04:23:46Z

Hi,

I tried with the /proc/sys/vm/overcommit_memory=2 and the system refused to
load the program altogether.

In this scenario is making overcommit_memory=2 a good idea?

Regards,
Abu.

-----Original Message-----
From: Robert Hancock [mailto:hancockr@shaw.ca]
Sent: Saturday, July 08, 2006 11:36 PM
To: Abu M. Muttalib
Cc: kernelnewbies@nl.linux.org; linux-newbie@vger.kernel.org;
linux-kernel@vger.kernel.org; linux-mm
Subject: Re: Commenting out out_of_memory() function in __alloc_pages()

Abu M. Muttalib wrote:
> Hi,
>
> I am getting the Out of memory.
>
> To circumvent the problem, I have commented the call to "out_of_memory(),
> and replaced "goto restart" with "goto nopage".
>
> At "nopage:" lable I have added a call to "schedule()" and then "return
> NULL" after "schedule()".

Bad idea - in the configuration you have, the system may need the
out-of-memory killer to free up memory, otherwise the system can
deadlock due to all memory being exhausted.

>
> I tried the modified kernel with a test application, the test application
is
> mallocing memory in a loop. Unlike as expected the process gets killed. On
> second run of the same application I am getting the page allocation
failure
> as expected but subsequently the system hangs.
>
> I am attaching the test application and the log herewith.
>
> I am getting this exception with kernel 2.6.13. With kernel
> 2.4.19-rmka7-pxa1 there was no problem.
>
> Why its so? What can I do to alleviate the OOM problem?

Please see Documentation/vm/overcommit-accounting in the kernel source tree.

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Robert Hancock Saskatoon, SK, Canada
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