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Date: Fri, 26 Oct 2018 23:12:30 +0300
From: Konstantin Belousov <kostikbel@gmail.com>
To: "Bennett, Ciunas" <ciunas.bennett@intel.com>
Cc: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org>
Subject: Re: Possible memory leak in the kernel (contigmalloc)
Message-ID: <20181026201230.GV5335@kib.kiev.ua>
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On Wed, Oct 24, 2018 at 04:27:52PM +0000, Bennett, Ciunas wrote:
> Hello,
> 
> I have encountered an issue with a kernel application that I have
> written, the issue might be caused by a memory leak in the kernel.
> The application allocates and deallocates contiguous memory using
> contigmalloc() and contigfree(). The application will fail after a
> period of time because there is not enough free contiguous memory
> left. There could be an issue with the freeing of memory when using
> the contigfree() function.
>

It is unlikely that there is an issue with a leak, but I would be not
surprised if your allocation/free pattern would cause fragmentation
on free lists that results in contigmalloc(9) failures after.

Look at the vmstat -z/vmstat -m output to see uma and malloc stats.
More interesting for your case can be the output from
	sysctl vm.phys_free
which provides information about the free queues and order of free pages
on them.