Re: [PATCH] mm/nommu.c:Dynamic alloc/free percpu area for nommu

[Sonic Zhang <sonic.adi@gmail.com>]

On Thu, Apr 8, 2010 at 10:43 AM, Tejun Heo <tj@kernel.org> wrote:
> Hello, Sonic.
>
>> I tested your patch on NOMMU bf561 with SMP enabled. It is compiled
>> and boots without problem. Because there are few percpu data defined
>> in bf561 SMP kernel, the functions in mm/percpu-km.c may not be
>> executed with a simple test. But, since these functions are simple
>> malloc/free, I don't see any problem.
>
> Great, thanks for testing.  Just in case, can you please test with the
> attached module?  In test-pcpu.c, the cmds table directs the module
> what to allocate and free.  { size > 0, tag } entry makes it allocate
> an area with the specified size and tag and { 0, tag } entry makes it
> free all areas with the matching tag.  The existing table makes pretty
> large amount of allocations and might not work very well on nommu
> configuration.  There are also several DEFINE_PER_CPU() instances to
> test module static percpu area alloc/free.  Please insmod/rmmod in
> loop and make sure it doesn't leak any memory or crashes the machine.
>

Tejun,

There is memory leak with you patch. Free memory continuously
decreases when running test_pcpu. After about 30 minutes, kernel hangs
in out_of_memory().


root/> while [ 1 ]; do modprobe test_pcpu; rmmod test_pcpu; cat
proc/meminfo; done


Sonic

> Thanks.
>
> --
> tejun
>