memory leakage -> howto discover the leak [Re: Potential memory leakage in 2.2.0 ?]

Andrea Arcangeli (andrea@e-mind.com)
Tue, 2 Feb 1999 17:11:55 +0100 (CET)


On Mon, 1 Feb 1999, Thierry Danis wrote:

> I let my 2.2.0-final box run other the last days with 'normal'

Please upgrade to 2.2.1 and then apply my version of the patch-ikd, (btw
the memleak detector part is been developed by Ingo Molnar and maintained
by Mike Galbraith):

ftp://e-mind.com/pub/linux/patch-ikd-arca/patch-ikd-arca-24-against-2.2.1.diff.gz

Then run make menuconfig and enable kernel debugging -> memleak detector.
BTW it works only on i386 arch.

Then recompile (also with `make debug`) and then reboot. Then you can read
linux/scripts/memleak/FAQ to know how to get data from /proc/memleak and
how to compare them. When you'll have discovered where is the leak please
let me/us know.

BTW, before complaining about a kernel mem leak I suggest you to check
that you don't have memory allocated in shm memory (due an userspace
leak). You can for example do a `killall5 -9; swapoff -a` and then run
`ipcs` to check that you have no one byte allocated in shm memory. The
swapoff -a is to flush all the swap cache memory from the memory (it could
be fooling your eyes ;). BTW, my kerenl tree avoid orphaned entried in the
swap cache.

Forget to tell don't complain about a memleak if you get an Oops some time
before (in such case there's a bug in the kenrel and not a leak). Once
your kernel has oopsed one time you are grately suggested to reset the
machine if you don't know the details of the kernel bug (once you have
logged the Oops and the old System.map of course ;).

Hope this helps to get some more detailed info.

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