Re: weird memory related problems, negative memory usage or fake memory usage?

[Andrea Arcangeli <andrea@suse.de>]

On Mon, Sep 24, 2001 at 07:03:20PM -0300, Rik van Riel wrote:
> [Andrea, please read this bugreport ...]
> 
> On Mon, 24 Sep 2001, Olivier Sessink wrote:
> 
> > after upgrade from 2.4.10pre8 to 2.4.10 I have weird problems,
> > Xfree sometimes shows up with 99.9% memory in top (on a box with
> > 512 mb), and in ps axl it has 4294989036 in the RSS column. When
> > this happens the box starts to kill some processes, starts
> > heavily swapping (top reports > 400MB in the cache, but the
> > machine is heavily swapping!!!) and is completely unusable.
> 
> > Since this makes the machine completely unusable, and since it is not
> > happening on 2.4.10pre8 I guess it is a bug ;-)
> 
> >   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
> >  1262 root       5 -10 50764  -1M  1320 S <   2.7 99.9   0:01 XFree86
> 
> 
> It seems Andrea wasn't careful with the merge and
> backed out some of the locking wrt mm->rss.

thanks for forwarding this report, actually I just noticed this here and
that's good so I can reproduce :)

it is possible it is my mistake, but I don't think so, infact I don't
recall to have changed rss stuff or locking around it. Incidentally the
first time I reproduced it here was after the tlb shootdown patch from
Ben was introduced, never reproduced it here previously with only my
changes.  However it is possibly just a coincidence.

> 
> Andrea, you may want to spend some time auditing
> your VM like has been done with the other 2.4 VM.
> 
> cheers,
> 
> Rik
> --
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> 
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> 


Andrea