panic: kmem_map too small at heavy packet traffic

[Tugrul Erdogan]

I have just pilled a PR.

The negative written value is directly malloc's size parameter (in fact
after some page size alignment enlargements operation). This parameter has
been defined as "unsigned long" but printing with "%ld" as signed long. So
if the size is very very big (more than 2^63 at amd64), the signed printing
can remark the first bit of size as sign bit then write the - sign. But I
think the size can not be so big, for this reason you are right, there must
be a
problem (the size parameter can come as negative or the enlargement
functions can destroy the size parameter).


On Sat, Jul 27, 2013 at 12:21 AM, Adrian Chadd <adrian at freebsd.org> wrote:

> Hi
>
> Have you filed a PR? This should get fixed.
>
> Also, being -ve is a problem. Is the value really negative? Is it
> wrapping badly?
>
>
>
> -adrian
>
> On 25 July 2013 07:57, Tugrul Erdogan <h.tugrul.erdogan at gmail.com> wrote:
> > howdy all,
> >
> > At my work, I am using 10.0-CURRENT on Intel(R) Xeon(R) E5620 with 16GB
> > ram. I am taking
> >
> > "panic: kmem_malloc(-548663296): kmem_map too small: 539459584 total
> allocated"
> >
> > message with configuration below:
> >
> > [root@ ~]# sysctl vm.kmem_size_min vm.kmem_size_max vm.kmem_size
> > vm.kmem_size_scale
> > vm.kmem_size_min: 0
> > vm.kmem_size_max: 329853485875
> > vm.kmem_size: 16686845952
> > vm.kmem_size_scale: 1
> > [root@ ~]# sysctl hw.physmem hw.usermem hw.realmem
> > hw.physmem: 17151787008
> > hw.usermem: 8282652672
> > hw.realmem: 18253611008
> > [root@ ~]# sysctl hw.pagesize hw.pagesizes hw.availpages
> > hw.pagesize: 4096
> > hw.pagesizes: 4096 2097152 0
> > hw.availpages: 4187448
> >
> >
> > When I compare vmstat and netstat output of boot time result and
> > subsequent result, the major difference are seemed at:
> >
> > pf_temp 0 0K - 79309736 128 | pf_temp 1077640 134705K - 84330076 128
> >
> > and after the panic at the core dump file the major vmstat difference is:
> >
> > temp 110 15K - 76212305 16,32,64,128,256 | temp 117 6742215K - 655115
> > 16,32,64,128,2
> >
> > When I explore the source code of kernel (at vm_kern.c and vm_map.c), I
> see
> > that the panic can occur with the cases at below:
> >
> > * negative malloc size parameter
> >
> > * longer than free buffer respect to kmem_map min_offset and max_offset
> > values
> >
> > * try to allocate when the root entry of map is the rightmost entry of
> map
> >
> > * try to allocate bigger than map's max_free value
> >
> > I think the panic occurs at mbuf creation process when calling malloc()
> as
> > a result of couldn't be able to allocate memory; but I don't understand
> why
> > one of this panic case activating? The memory is almost empty but the
> > device is saying kmem_map small when using about 0.5GB memory purely. How
> > can i solve this panic problem?
> >
> > Thank you all for your time.
> >
> > -- Best Wishes,
> >
> > Tugrul Erdogan
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