From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752948AbcKRIaq (ORCPT ); Fri, 18 Nov 2016 03:30:46 -0500 Received: from mx2.suse.de ([195.135.220.15]:54944 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752550AbcKRIao (ORCPT ); Fri, 18 Nov 2016 03:30:44 -0500 Date: Fri, 18 Nov 2016 09:30:42 +0100 From: Jan Kara To: Johannes Weiner Cc: Andrew Morton , Jan Kara , "Kirill A. Shutemov" , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 9/9] mm: workingset: restore refault tracking for single-page files Message-ID: <20161118083042.GI18676@quack2.suse.cz> References: <20161117191138.22769-1-hannes@cmpxchg.org> <20161117193244.GF23430@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161117193244.GF23430@cmpxchg.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Looks good. You can add: Reviewed-by: Jan Kara 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 SUSE Labs, CR From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 556926B03BA for ; Fri, 18 Nov 2016 03:30:44 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id s63so8478837wms.7 for ; Fri, 18 Nov 2016 00:30:44 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id v130si1578061wmf.126.2016.11.18.00.30.43 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 18 Nov 2016 00:30:43 -0800 (PST) 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 Message-ID: <20161118083042.GI18676@quack2.suse.cz> References: <20161117191138.22769-1-hannes@cmpxchg.org> <20161117193244.GF23430@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161117193244.GF23430@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Jan Kara , "Kirill A. Shutemov" , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com 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 Looks good. You can add: Reviewed-by: Jan Kara 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 SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org