On Thu, Jan 23, 2014 at 02:22:12PM -0500, Johannes Weiner wrote:

On Thu, Jan 23, 2014 at 02:20:14PM +0900, Minchan Kim wrote:

quoted

On Wed, Jan 22, 2014 at 01:42:17PM -0500, Johannes Weiner wrote:

quoted

On Mon, Jan 13, 2014 at 04:39:47PM +0900, Minchan Kim wrote:

quoted

On Fri, Jan 10, 2014 at 01:10:43PM -0500, Johannes Weiner wrote:

quoted

@@ -123,9 +129,39 @@ static void page_cache_tree_delete(struct address_space *mapping,
 		 * same time and miss a shadow entry.
 		 */
 		smp_wmb();
-	} else
-		radix_tree_delete(&mapping->page_tree, page->index);
+	}
 	mapping->nrpages--;
+
+	if (!node) {
+		/* Clear direct pointer tags in root node */
+		mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
+		radix_tree_replace_slot(slot, shadow);
+		return;
+	}
+
+	/* Clear tree tags for the removed page */
+	index = page->index;
+	offset = index & RADIX_TREE_MAP_MASK;
+	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
+		if (test_bit(offset, node->tags[tag]))
+			radix_tree_tag_clear(&mapping->page_tree, index, tag);
+	}
+
+	/* Delete page, swap shadow entry */
+	radix_tree_replace_slot(slot, shadow);
+	node->count--;
+	if (shadow)
+		node->count += 1U << RADIX_TREE_COUNT_SHIFT;

Nitpick2:
It should be a function of workingset.c rather than exposing
RADIX_TREE_COUNT_SHIFT?

IMO, It would be better to provide some accessor functions here, too.

The shadow maintenance and node lifetime management are pretty
interwoven to share branches and reduce instructions as these are
common paths.  I don't see how this could result in cleaner code while
keeping these advantages.

What I want is just put a inline accessor in somewhere like workingset.h

static inline void inc_shadow_entry(struct radix_tree_node *node)
{
    node->count += 1U << RADIX_TREE_COUNT_MASK;
}

So, anyone don't need to know that node->count upper bits present
count of shadow entry.

Okay, but then you have to cover lower bits as well, without explicit
higher bit access it would be confusing to use the mask for lower
bits.

Something like the following?

LGTM.

-- 
Kind regards,
Minchan Kim

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