Re: 2.5.67-mm3

William Lee Irwin III
2003-04-15T02:00:57Z

On Mon, Apr 14, 2003 at 01:53:13AM -0700, Andrew Morton wrote:
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.5/2.5.67/2.5.67-mm3/
>
> A bunch of new fixes, and a framebuffer update. This should work a bit
> better than -mm2.

If one's goal is to free highmem pages, shrink_slab() is an ineffective
method of recovering them, as slab pages are all ZONE_NORMAL or ZONE_DMA.
Hence, this "FIXME: do not do for zone highmem". Presumably this is a
question of policy, as highmem allocations may be satisfied by reaping
slab pages and handing them back; but the FIXME says what we should do.

diff -urpN mm3-2.5.67-1/mm/vmscan.c mm3-2.5.67-2/mm/vmscan.c
--- mm3-2.5.67-1/mm/vmscan.c 2003-04-14 18:08:15.000000000 -0700
+++ mm3-2.5.67-2/mm/vmscan.c 2003-04-14 18:16:41.000000000 -0700
@@ -134,11 +134,9 @@ void remove_shrinker(struct shrinker *sh
* If the vm encounted mapped pages on the LRU it increase the pressure on
* slab to avoid swapping.
*
- * FIXME: do not do for zone highmem
- *
* We do weird things to avoid (scanned*seeks*entries) overflowing 32 bits.
*/
-static int shrink_slab(long scanned, unsigned int gfp_mask)
+static int shrink_slab(long scanned, unsigned int gfp_mask)
{
struct shrinker *shrinker;
long pages;
@@ -835,7 +833,8 @@ try_to_free_pages(struct zone *classzone

/* Take a nap, wait for some writeback to complete */
blk_congestion_wait(WRITE, HZ/10);
- shrink_slab(total_scanned, gfp_mask);
+ if (classzone - classzone->zone_pgdat->node_zones < ZONE_HIGHMEM)
+ shrink_slab(total_scanned, gfp_mask);
}
if (gfp_mask & __GFP_FS)
out_of_memory();
@@ -895,7 +894,8 @@ static int balance_pgdat(pg_data_t *pgda
max_scan = SWAP_CLUSTER_MAX;
to_free -= shrink_zone(zone, max_scan, GFP_KERNEL,
to_reclaim, &nr_mapped, ps, priority);
- shrink_slab(max_scan + nr_mapped, GFP_KERNEL);
+ if (i < ZONE_HIGHMEM)
+ shrink_slab(max_scan + nr_mapped, GFP_KERNEL);
if (zone->all_unreclaimable)
continue;
if (zone->pages_scanned > zone->present_pages * 2)