From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752298AbcKRHaf (ORCPT ); Fri, 18 Nov 2016 02:30:35 -0500 Received: from mx2.suse.de ([195.135.220.15]:50562 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751243AbcKRHab (ORCPT ); Fri, 18 Nov 2016 02:30:31 -0500 Date: Fri, 18 Nov 2016 08:30:29 +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 2/9] mm: khugepaged: fix radix tree node leak in shmem collapse error path Message-ID: <20161118073029.GB18676@quack2.suse.cz> References: <20161117191138.22769-1-hannes@cmpxchg.org> <20161117191138.22769-3-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161117191138.22769-3-hannes@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 14:11:31, Johannes Weiner wrote: > The radix tree counts valid entries in each tree node. Entries stored > in the tree cannot be removed by simpling storing NULL in the slot or > the internal counters will be off and the node never gets freed again. > > When collapsing a shmem page fails, restore the holes that were filled > with radix_tree_insert() with a proper radix tree deletion. > > Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages") > Reported-by: Jan Kara > Signed-off-by: Johannes Weiner Looks good. You can add: Reviewed-by: Jan Kara Honza > --- > mm/khugepaged.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index bdfdab40a813..d553c294de40 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -1523,9 +1523,11 @@ static void collapse_shmem(struct mm_struct *mm, > if (!page || iter.index < page->index) { > if (!nr_none) > break; > - /* Put holes back where they were */ > - radix_tree_replace_slot(slot, NULL); > nr_none--; > + /* Put holes back where they were */ > + radix_tree_delete(&mapping->page_tree, > + iter.index); > + slot = radix_tree_iter_next(&iter); > continue; > } > > -- > 2.10.2 > -- Jan Kara SUSE Labs, CR