Re: Kernel 2.6.8.1: swap storm of death - nr_requests > 1024 on swap partition

Andrew Morton
2004-08-29T22:28:20Z

William Lee Irwin III <wli@holomorphy.com> wrote:
>
> On Sun, Aug 29, 2004 at 01:59:17PM -0700, Andrew Morton wrote:
> > The changlog wasn't that detailed ;)
> > But yes, it's the large nr_requests which is tripping up swapout. I'm
> > assuming that when a process exits with its anonymous memory still under
> > swap I/O we're forgetting to actually free the pages when the I/O
> > completes. So we end up with a ton of zero-ref swapcache pages on the LRU.
> > I assume. Something odd's happening, that's for sure.
>
> Maybe we need to be checking for this in end_swap_bio_write() or
> rotate_reclaimable_page()?

Maybe. I thought a get_page() in swap_writepage() and a put_page() in
end_swap_bio_write() would cause the page to be freed. But not. It needs
some actual real work done on it.