The page reclaiming logic operates on a per-zone basis.  This patch
introduces a general try_to_free_pages_nozone() which just tries to
free 32 pages from *every* zone.

This function is only used from free_more_memory() in fs/buffer.c. 
When we're trying to grow buffers against a device for filesystem
metadata.

It seems to me that free_more_memory() simply is not needed - we're
already retrying the allocation over in buffer.c, and it seems that
this will do most everything which the call to try_to_free_pages()
would do?



=====================================

--- 2.4.19-pre4/fs/buffer.c~aa-120-try_to_free_pages_nozone	Tue Mar 26 23:11:31 2002
+++ 2.4.19-pre4-akpm/fs/buffer.c	Tue Mar 26 23:11:31 2002
@@ -727,12 +727,8 @@ void __invalidate_buffers(kdev_t dev, in
 
 static void free_more_memory(void)
 {
-	zone_t * zone = contig_page_data.node_zonelists[GFP_NOFS & GFP_ZONEMASK].zones[0];
-	
-	balance_dirty();
 	wakeup_bdflush();
-	try_to_free_pages(zone, GFP_NOFS, 0);
-	run_task_queue(&tq_disk);
+	try_to_free_pages_nozone(GFP_NOIO);
 	current->policy |= SCHED_YIELD;
 	__set_current_state(TASK_RUNNING);
 	schedule();
--- 2.4.19-pre4/include/linux/swap.h~aa-120-try_to_free_pages_nozone	Tue Mar 26 23:11:31 2002
+++ 2.4.19-pre4-akpm/include/linux/swap.h	Tue Mar 26 23:11:31 2002
@@ -113,6 +113,7 @@ extern void swap_setup(void);
 extern wait_queue_head_t kswapd_wait;
 extern int FASTCALL(try_to_free_pages(zone_t *, unsigned int, unsigned int));
 extern int vm_vfs_scan_ratio, vm_cache_scan_ratio, vm_lru_balance_ratio, vm_passes, vm_gfp_debug, vm_mapped_ratio;
+extern int FASTCALL(try_to_free_pages_nozone(unsigned int));
 
 /* linux/mm/page_io.c */
 extern void rw_swap_page(int, struct page *);
--- 2.4.19-pre4/mm/page_alloc.c~aa-120-try_to_free_pages_nozone	Tue Mar 26 23:11:31 2002
+++ 2.4.19-pre4-akpm/mm/page_alloc.c	Tue Mar 26 23:11:31 2002
@@ -510,6 +510,30 @@ unsigned int nr_free_highpages (void)
 }
 #endif
 
+int try_to_free_pages_nozone(unsigned int gfp_mask)
+{
+	pg_data_t *pgdat = pgdat_list;
+	zonelist_t *zonelist;
+	zone_t **zonep;
+	int ret = 0;
+	unsigned long pf_free_pages;
+
+	pf_free_pages = current->flags & PF_FREE_PAGES;
+	current->flags &= ~PF_FREE_PAGES;
+
+	do {
+		zonelist = pgdat->node_zonelists + (gfp_mask & GFP_ZONEMASK);
+		zonep = zonelist->zones;
+
+		ret |= try_to_free_pages(*zonep, gfp_mask, 0);
+
+		pgdat = pgdat->node_next;
+	} while (pgdat);
+
+	current->flags |= pf_free_pages;
+	return ret;
+}
+
 #define K(x) ((x) << (PAGE_SHIFT-10))
 
 /*