Re: [PATCH 2.6.20-rc1 00/10] Kernel memory leak detector 0.13

From: Ingo Molnar
Date: Sun Dec 17 2006 - 08:31:45 EST



* Catalin Marinas <catalin.marinas@xxxxxxxxx> wrote:

> On 17/12/06, Ingo Molnar <mingo@xxxxxxx> wrote:
> >one more thing: after bootup i need to access the /debug/memleak file
> >twice to get any output from it - is that normal? The first 'cat
> >/debug/memleak' gives no output (but there's the usual scanning
> >delay, so memleak does do its work).
>
> Yes, this is normal. Especially on SMP, I get some transient reports,
> probably caused by pointers hold in registers (even more visible on
> ARM due to the bigger number of registers per CPU). Reporting a leak
> only if it was seen at least once before greatly reduces the false
> positives (this is configurable as well but I'll drop the
> configuration option). Without this, you could see that, at every
> scan, the reported pointers are different.
>
> Some people testing kmemleak used to read the /debug/memleak file
> periodically from a script and this wasn't noticeable. It would be
> even better if, as you suggested, I schedule a periodic memory
> scanning.

yeah. You could also use the allocation timestamp to exclude too young
entries. (if something really leaked then it will be a leak in 10
minutes too)

Ingo
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