Re: ZONE_NORMAL exhaustion (dcache slab)

[Andrew Morton <akpm@digeo.com>]

"Martin J. Bligh" wrote:
> 
> >> My big NUMA box went OOM over the weekend and started killing things
> >> for no good reason (2.5.43-mm2). Probably running some background
> >> updatedb for locate thing, not doing any real work.
> >>
> >> meminfo:
> >>
> >
> > Looks like a plain dentry leak to me.  Very weird.
> >
> > Did the machine recover and run normally?
> 
> Nope, kept OOMing and killing everything .

Something broke.

> > Was it possible to force the dcache to shrink? (a cat /dev/hda1
> > would do that nicely)
> 
> Well, I didn't try that, but even looking at man pages got oom killed,
> so I guess not ... were you looking at the cat /dev/hda1 to fill pagecache
> or something? I have 16Gb of highmem (pretty much all ununsed) so
> presumably that'd fill the highmem first (pagecache?)

Blockdevices only use ZONE_NORMAL for their pagecache.  That cat will
selectively put pressure on the normal zone (and DMA zone, of course).
 
> > Is it reproducible?
> 
> Will try again. Presumably "find /" should do it? ;-)

You must have a lot of files.

Actually, I expect a `find /' will only stat directories,
whereas an `ls -lR /' will stat plain files as well.  Same
thing for dcache, but the ls will push the icache harder.

I don't know if updatedb stats regular files.  Presumably not.