[Bug 859] New: bitmap:port appears to be using 8 bytes of kernel memory per port, rather than 1 bit.

[bugzilla-daemon at netfilter.org]

https://bugzilla.netfilter.org/show_bug.cgi?id=859

           Summary: bitmap:port appears to be using 8 bytes of kernel
                    memory per port, rather than 1 bit.
           Product: ipset
           Version: unspecified
          Platform: x86_64
        OS/Version: All
            Status: NEW
          Severity: critical
          Priority: P5
         Component: default
        AssignedTo: netfilter-buglog at lists.netfilter.org
        ReportedBy: quentin at armitage.org.uk
   Estimated Hours: 0.0


Using ipset version 6.19 on kernel version 3.6.11, a bitmap:ip range 1-65535 is
reported to be using 8304 bytes of memory. With a kernel version 3.11.3, the
same size bitmap:ip is reported to be using 524424 bytes of memory.

# uname -r
3.6.11-4.fc16.x86_64
# ipset create fred bitmap:port range 1-65535
# ipset list fred
Name: fred
Type: bitmap:port
Revision: 0
Header: range 1-65535
Size in memory: 8304
References: 0
Members:

# uname -r
3.11.3-201.fc19.x86_64
# ipset create fred bitmap:port range 1-65535
# ipset list fred
Name: fred
Type: bitmap:port
Revision: 1
Header: range 1-65535
Size in memory: 524424
References: 0
Members:

A 3.7.5 kernel reports memory utilisation of 8260, so slightly lower than
3.6.11. Unfortunately I don't have any kernels between 3.7.5 and 3.11.3
running.

Further checks show that for every additional port in the bitmap, kernel 3.11.3
reports adding 8 bytes to the size of the bitmap.

A bitmap:ip does NOT have the same problem.

I assume it is a problem in the kernel, since I am using ipset version 6.19 on
both systems (I have also tried ipset v6.20 on the 3.11.3 system, but it shows
the same problem).

Is the 3.11.3 kernel using an excessive amount of memory for bitmap:port, or is
it incorrectly reporting the amount of memory used?

I've marked this as critical in case the kernel is using the excessive amount
of memory. If it is just the amount of memory being used, then I'm happy for
the severity to be lowered.

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