/proc/<pid>/maps question....why aren't adjacent memory chunks merged?

[Chris Friesen]

Hi,

I've got a system running a somewhat-modified 2.6.27 on 64-bit x86.

While investigating a userspace memory leak issue I noticed that
/proc/<pid>/maps showed a bunch of adjacent anonymous memory chunks with
identical permissions:

7fd048000000-7fd04c000000 rw-p 00000000 00:00 0
7fd04c000000-7fd050000000 rw-p 00000000 00:00 0
7fd050000000-7fd054000000 rw-p 00000000 00:00 0
7fd054000000-7fd058000000 rw-p 00000000 00:00 0
7fd058000000-7fd05c000000 rw-p 00000000 00:00 0
7fd05c000000-7fd060000000 rw-p 00000000 00:00 0
7fd060000000-7fd064000000 rw-p 00000000 00:00 0
7fd064000000-7fd068000000 rw-p 00000000 00:00 0
7fd068000000-7fd06c000000 rw-p 00000000 00:00 0
7fd06c000000-7fd070000000 rw-p 00000000 00:00 0
7fd070000000-7fd074000000 rw-p 00000000 00:00 0
7fd074000000-7fd078000000 rw-p 00000000 00:00 0
7fd078000000-7fd07c000000 rw-p 00000000 00:00 0
7fd07c000000-7fd07fffe000 rw-p 00000000 00:00 0

I was under the impression that the kernel would merge areas together in
this circumstance.  Does anyone have an idea about what's going on here?

Thanks,

Chris
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