From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0299CC433DF for ; Wed, 20 May 2020 14:24:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0B04205CB for ; Wed, 20 May 2020 14:24:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728222AbgETOYV (ORCPT ); Wed, 20 May 2020 10:24:21 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33216 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727083AbgETOW2 (ORCPT ); Wed, 20 May 2020 10:22:28 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1jbPc0-00036v-5j; Wed, 20 May 2020 15:22:24 +0100 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1jbPby-007DWt-11; Wed, 20 May 2020 15:22:22 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Anna Schumaker" , "Trond Myklebust" , "Trond Myklebust" , "Benjamin Coddington" Date: Wed, 20 May 2020 15:15:04 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 96/99] NFS: Directory page cache pages need to be locked when read In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.84-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 114de38225d9b300f027e2aec9afbb6e0def154b upstream. When a NFS directory page cache page is removed from the page cache, its contents are freed through a call to nfs_readdir_clear_array(). To prevent the removal of the page cache entry until after we've finished reading it, we must take the page lock. Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir") Signed-off-by: Trond Myklebust Reviewed-by: Benjamin Coddington Signed-off-by: Anna Schumaker [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- fs/nfs/dir.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -671,8 +671,6 @@ int nfs_readdir_filler(nfs_readdir_descr static void cache_page_release(nfs_readdir_descriptor_t *desc) { - if (!desc->page->mapping) - nfs_readdir_clear_array(desc->page); page_cache_release(desc->page); desc->page = NULL; } @@ -686,19 +684,28 @@ struct page *get_cache_page(nfs_readdir_ /* * Returns 0 if desc->dir_cookie was found on page desc->page_index + * and locks the page to prevent removal from the page cache. */ static -int find_cache_page(nfs_readdir_descriptor_t *desc) +int find_and_lock_cache_page(nfs_readdir_descriptor_t *desc) { int res; desc->page = get_cache_page(desc); if (IS_ERR(desc->page)) return PTR_ERR(desc->page); - - res = nfs_readdir_search_array(desc); + res = lock_page_killable(desc->page); if (res != 0) - cache_page_release(desc); + goto error; + res = -EAGAIN; + if (desc->page->mapping != NULL) { + res = nfs_readdir_search_array(desc); + if (res == 0) + return 0; + } + unlock_page(desc->page); +error: + cache_page_release(desc); return res; } @@ -713,7 +720,7 @@ int readdir_search_pagecache(nfs_readdir desc->last_cookie = 0; } do { - res = find_cache_page(desc); + res = find_and_lock_cache_page(desc); } while (res == -EAGAIN); return res; } @@ -752,7 +759,6 @@ int nfs_do_filldir(nfs_readdir_descripto desc->eof = 1; kunmap(desc->page); - cache_page_release(desc); dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (unsigned long long)*desc->dir_cookie, res); return res; @@ -798,13 +804,13 @@ int uncached_readdir(nfs_readdir_descrip status = nfs_do_filldir(desc); + out_release: + nfs_readdir_clear_array(desc->page); + cache_page_release(desc); out: dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status); return status; - out_release: - cache_page_release(desc); - goto out; } /* The file offset position represents the dirent entry number. A @@ -870,6 +876,8 @@ static int nfs_readdir(struct file *file break; res = nfs_do_filldir(desc); + unlock_page(desc->page); + cache_page_release(desc); if (res < 0) break; } while (!desc->eof);