On Mon 07-11-16 14:07:41, 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 <[email protected]>
The patch looks good to me. You can add: Reviewed-by: Jan Kara <[email protected]> Honza > --- > mm/filemap.c | 13 +++---------- > 1 file changed, 3 insertions(+), 10 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 438f0b54f8fd..55a3b136a527 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -178,19 +178,12 @@ static void page_cache_tree_delete(struct address_space > *mapping, > > radix_tree_clear_tags(&mapping->page_tree, 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; > - } > - > __radix_tree_replace(&mapping->page_tree, node, slot, shadow); > > - if (!node) > + if (!node) { > + VM_BUG_ON_PAGE(nr != 1, page); > break; > + } > > if (!shadow && > __radix_tree_delete_node(&mapping->page_tree, node)) > -- > 2.10.1 > -- Jan Kara <[email protected]> SUSE Labs, CR
