On Tue, 26 Apr 2011 08:36:53 +0100 Mel Gorman <mgorman@xxxxxxx> wrote:
> +/*
> + * Throttle direct reclaimers if backing storage is backed by the network
> + * and the PFMEMALLOC reserve for the preferred node is getting dangerously
> + * depleted. kswapd will continue to make progress and wake the processes
> + * when the low watermark is reached
> + */
> +static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
> + nodemask_t *nodemask)
> +{
> + struct zone *zone;
> + int high_zoneidx = gfp_zone(gfp_mask);
> + DEFINE_WAIT(wait);
> +
> + /* Check if the pfmemalloc reserves are ok */
> + first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
> + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> + TASK_INTERRUPTIBLE);
> + if (pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx))
> + goto out;
> +
> + /* Throttle */
> + do {
> + schedule();
> + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait,
> + TASK_INTERRUPTIBLE);
> + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) &&
> + !fatal_signal_pending(current));
> +
> +out:
> + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait);
> +}
You are doing an interruptible wait, but only checking for fatal signals.
So if a non-fatal signal arrives, you will busy-wait.
So I suspect you want TASK_KILLABLE, so just use:
wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
pgmemalloc_watermark_ok(zone->zone_pgdata,
high_zoneidx));
(You also have an extraneous call to finish_wait)
NeilBrown
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