Return-Path: Received: from smtp-out.google.com ([216.239.44.51]:38229 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932142Ab0LAVDE (ORCPT ); Wed, 1 Dec 2010 16:03:04 -0500 Received: from hpaq1.eem.corp.google.com (hpaq1.eem.corp.google.com [172.25.149.1]) by smtp-out.google.com with ESMTP id oB1L2wAh024265 for ; Wed, 1 Dec 2010 13:02:58 -0800 Received: from pzk2 (pzk2.prod.google.com [10.243.19.130]) by hpaq1.eem.corp.google.com with ESMTP id oB1L2FhU007492 for ; Wed, 1 Dec 2010 13:02:56 -0800 Received: by pzk2 with SMTP id 2so1278216pzk.32 for ; Wed, 01 Dec 2010 13:02:56 -0800 (PST) Date: Wed, 1 Dec 2010 13:02:48 -0800 (PST) From: Hugh Dickins To: Andrew Morton cc: Trond Myklebust , Linus Torvalds , Nick Piggin , Nick Bowler , Linux Kernel Mailing List , linux-nfs@vger.kernel.org, Rik van Riel , Christoph Hellwig , Al Viro Subject: Re: [PATCH v2 3/3] NFS: Fix a memory leak in nfs_readdir In-Reply-To: <20101201123341.d12ef362.akpm@linux-foundation.org> Message-ID: References: <1291217804-11257-1-git-send-email-Trond.Myklebust@netapp.com> <1291217804-11257-2-git-send-email-Trond.Myklebust@netapp.com> <20101201150428.GA2879@elliptictech.com> <1291217804-11257-3-git-send-email-Trond.Myklebust@netapp.com> <1291217804-11257-4-git-send-email-Trond.Myklebust@netapp.com> <1291229669.6609.24.camel@heimdal.trondhjem.org> <1291234251.6609.39.camel@heimdal.trondhjem.org> <20101201123341.d12ef362.akpm@linux-foundation.org> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Wed, 1 Dec 2010, Andrew Morton wrote: > On Wed, 01 Dec 2010 15:10:50 -0500 > Trond Myklebust wrote: > > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -602,6 +602,7 @@ struct address_space_operations { > > sector_t (*bmap)(struct address_space *, sector_t); > > void (*invalidatepage) (struct page *, unsigned long); > > int (*releasepage) (struct page *, gfp_t); > > + void (*freepage)(struct page *); > > ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, > > loff_t offset, unsigned long nr_segs); > > int (*get_xip_mem)(struct address_space *, pgoff_t, int, > > It would be good to think about and then clearly spell out exactly what > state the page is in here. It is locked, and I assume clean and not > under writeback. What about its refcount, freezedness status and > eligibility for lookups? > > And as Hugh pointed out, some callees might needs the address_space* > although we can perhaps defer that until such a callee turns up. > If/when that happens we might have a problem though: if this locked > page is no longer attached to the address_space then what now pins the > address_space, protecting it from inode reclaim? That's an excellent point and trumps mine: it would be actively wrong to provide the struct address_space *mapping arg I was asking for. (Bet someone then tries stashing it away via page->private though.) Hugh