Re: 2.5.74-mm3 OOM killer fubared ?

Andrew Morton (
Thu, 10 Jul 2003 10:38:10 -0700

"Miquel van Smoorenburg" <> wrote:
> I was running 2.5.74 on our newsfeeder box for a day without
> problems (and 2.5.72-mm2 for weeks before that).

And how was 2.5.72-mm2 performing, generally?

> Now with 2.5.74-mm3 (booted 11 hours ago) it keeps killing processes
> for no apparent reason:
> ...
> I notice that in -mm3 this was deleted relative to -vanilla:
> -
> - /*
> - * Enough swap space left? Not OOM.
> - */
> - if (nr_swap_pages > 0)
> - return;
> .. is that what causes this?

Yes. That was a "hmm, I wonder what happens if I do this" patch. It's
interesting that we're going down that code path.

Is your INND configured to use the strange mmap(MAP_SHARED) of a blockdev
thing? That could explain the scanning hysteria.

> Related mm question - this box is a news server, which does a lot
> of streaming I/O, and also keeps a history database open. I have the
> idea that the streaming I/O evicts the history database hash and
> index file caches from memory, which I do not want. Any chance of
> a control on a filedescriptor that tells it how persistant to be
> in caching file data ? E.g. a sort of "nice" for the cache, so that
> I could say that streaming data may be flushed from buffers/cache
> earlier than other data (where the other data would be the
> database files) ?

Makes sense. We can use posix_fadvise(POSIX_FADV_NOREUSE) as a hint to
tell the VM/VFS to throw away old pages. I'll take a look at that.

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