From: Rik van Riel During an AIM7 run on a 16GB system, fork started failing around 32000 threads, despite the system having plenty of free swap and 15GB of pageable memory. If normal pageout does not result in contiguous free pages for kernel stacks, fall back to lumpy reclaim instead of failing fork or doing excessive pageout IO. I do not know whether this change is needed due to the extreme stress test or because the inactive list is a smaller fraction of system memory on huge systems. Signed-off-by: Rik van Riel Index: linux-2.6.26-rc2-mm1/mm/vmscan.c =================================================================== --- linux-2.6.26-rc2-mm1.orig/mm/vmscan.c 2008-05-16 14:04:57.000000000 -0400 +++ linux-2.6.26-rc2-mm1/mm/vmscan.c 2008-05-16 14:05:05.000000000 -0400 @@ -857,7 +857,8 @@ int isolate_lru_page(struct page *page) * of reclaimed pages */ static unsigned long shrink_inactive_list(unsigned long max_scan, - struct zone *zone, struct scan_control *sc, int file) + struct zone *zone, struct scan_control *sc, + int priority, int file) { LIST_HEAD(page_list); struct pagevec pvec; @@ -875,8 +876,19 @@ static unsigned long shrink_inactive_lis unsigned long nr_freed; unsigned long nr_active; unsigned int count[NR_LRU_LISTS] = { 0, }; - int mode = (sc->order > PAGE_ALLOC_COSTLY_ORDER) ? - ISOLATE_BOTH : ISOLATE_INACTIVE; + int mode = ISOLATE_INACTIVE; + + /* + * If we need a large contiguous chunk of memory, or have + * trouble getting a small set of contiguous pages, we + * will reclaim both active and inactive pages. + * + * We use the same threshold as pageout congestion_wait below. + */ + if (sc->order > PAGE_ALLOC_COSTLY_ORDER) + mode = ISOLATE_BOTH; + else if (sc->order && priority < DEF_PRIORITY - 2) + mode = ISOLATE_BOTH; nr_taken = sc->isolate_pages(sc->swap_cluster_max, &page_list, &nr_scan, sc->order, mode, @@ -1161,7 +1173,7 @@ static unsigned long shrink_list(enum lr shrink_active_list(nr_to_scan, zone, sc, priority, file); return 0; } - return shrink_inactive_list(nr_to_scan, zone, sc, file); + return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); } /* -- All Rights Reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/