Re: [PATCH][5/?] count writeback pages in nr_scanned

[Andrew Morton <akpm@osdl.org>]

Rik van Riel <riel@redhat.com> wrote:
>
> OOM kills have been observed with 70% of the pages in lowmem being
>  in the writeback state.  If we count those pages in sc->nr_scanned,
>  the VM should throttle and wait for IO completion, instead of OOM
>  killing.

I'll queue this up:



From: Rik van Riel <riel@redhat.com>

OOM kills have been observed with 70% of the pages in lowmem being in the
writeback state.  If we count those pages in sc->nr_scanned, the VM should
throttle and wait for IO completion, instead of OOM killing.

(akpm: this is how the code was designed to work - we broke it six months
ago).

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 25-akpm/mm/vmscan.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff -puN mm/vmscan.c~vmscan-count-writeback-pages-in-nr_scanned mm/vmscan.c
--- 25/mm/vmscan.c~vmscan-count-writeback-pages-in-nr_scanned	2005-01-05 15:24:53.730874336 -0800
+++ 25-akpm/mm/vmscan.c	2005-01-05 15:25:48.286580608 -0800
@@ -369,14 +369,14 @@ static int shrink_list(struct list_head 
 
 		BUG_ON(PageActive(page));
 
-		if (PageWriteback(page))
-			goto keep_locked;
-
 		sc->nr_scanned++;
 		/* Double the slab pressure for mapped and swapcache pages */
 		if (page_mapped(page) || PageSwapCache(page))
 			sc->nr_scanned++;
 
+		if (PageWriteback(page))
+			goto keep_locked;
+
 		referenced = page_referenced(page, 1, sc->priority <= 0);
 		/* In active use or really unfreeable?  Activate it. */
 		if (referenced && page_mapping_inuse(page))
_