Messages in this thread | | | Date | Fri, 18 Nov 2016 09:30:42 +0100 | From | Jan Kara <> | Subject | Re: [PATCH 9/9] mm: workingset: restore refault tracking for single-page files |
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On Thu 17-11-16 14:32:44, Johannes Weiner wrote: > Shadow entries in the page cache used to be accounted behind the radix > tree implementation's back in the upper bits of node->count, and the > radix tree code extending a single-entry tree with a shadow entry in > root->rnode would corrupt that counter. As a result, we could not put > shadow entries at index 0 if the tree didn't have any other entries, > and that means no refault detection for any single-page file. > > Now that the shadow entries are tracked natively in the radix tree's > exceptional counter, this is no longer necessary. Extending and > shrinking the tree from and to single entries in root->rnode now does > the right thing when the entry is exceptional, remove that limitation. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> --- > mm/filemap.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 7d92032277ff..ae7b6992aded 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -164,14 +164,7 @@ static void page_cache_tree_delete(struct address_space *mapping, > __radix_tree_lookup(&mapping->page_tree, page->index + i, > &node, &slot); > > - if (!node) { > - VM_BUG_ON_PAGE(nr != 1, page); > - /* > - * We need a node to properly account shadow > - * entries. Don't plant any without. XXX > - */ > - shadow = NULL; > - } > + VM_BUG_ON_PAGE(!node && nr != 1, page); > > radix_tree_clear_tags(&mapping->page_tree, node, slot); > __radix_tree_replace(&mapping->page_tree, node, slot, shadow, > -- > 2.10.2 > -- Jan Kara <jack@suse.com> SUSE Labs, CR
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