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 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 C8459C432C0 for ; Wed, 20 Nov 2019 15:45:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A55CC20709 for ; Wed, 20 Nov 2019 15:45:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729943AbfKTPpN (ORCPT ); Wed, 20 Nov 2019 10:45:13 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52638 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729747AbfKTPkR (ORCPT ); Wed, 20 Nov 2019 10:40:17 -0500 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iXS5U-0004ak-Dl; Wed, 20 Nov 2019 15:40:12 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1iXS5T-0004HG-C9; Wed, 20 Nov 2019 15:40:11 +0000 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 , "Trond Myklebust" , "John Hubbard" Date: Wed, 20 Nov 2019 15:37:33 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 23/83] NFSv4: Fix a potential sleep while atomic in nfs4_do_reclaim() In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 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 3.16.78-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit c77e22834ae9a11891cb613bd9a551be1b94f2bc upstream. John Hubbard reports seeing the following stack trace: nfs4_do_reclaim rcu_read_lock /* we are now in_atomic() and must not sleep */ nfs4_purge_state_owners nfs4_free_state_owner nfs4_destroy_seqid_counter rpc_destroy_wait_queue cancel_delayed_work_sync __cancel_work_timer __flush_work start_flush_work might_sleep: (kernel/workqueue.c:2975: BUG) The solution is to separate out the freeing of the state owners from nfs4_purge_state_owners(), and perform that outside the atomic context. Reported-by: John Hubbard Fixes: 0aaaf5c424c7f ("NFS: Cache state owners after files are closed") Signed-off-by: Trond Myklebust Signed-off-by: Ben Hutchings --- fs/nfs/nfs4_fs.h | 3 ++- fs/nfs/nfs4client.c | 5 ++++- fs/nfs/nfs4state.c | 27 ++++++++++++++++++++++----- 3 files changed, 28 insertions(+), 7 deletions(-) --- a/fs/nfs/nfs4_fs.h +++ b/fs/nfs/nfs4_fs.h @@ -419,7 +419,8 @@ static inline void nfs4_schedule_session extern struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *, struct rpc_cred *, gfp_t); extern void nfs4_put_state_owner(struct nfs4_state_owner *); -extern void nfs4_purge_state_owners(struct nfs_server *); +extern void nfs4_purge_state_owners(struct nfs_server *, struct list_head *); +extern void nfs4_free_state_owners(struct list_head *head); extern struct nfs4_state * nfs4_get_open_state(struct inode *, struct nfs4_state_owner *); extern void nfs4_put_open_state(struct nfs4_state *); extern void nfs4_close_state(struct nfs4_state *, fmode_t); --- a/fs/nfs/nfs4client.c +++ b/fs/nfs/nfs4client.c @@ -682,9 +682,12 @@ int nfs41_walk_client_list(struct nfs_cl static void nfs4_destroy_server(struct nfs_server *server) { + LIST_HEAD(freeme); + nfs_server_return_all_delegations(server); unset_pnfs_layoutdriver(server); - nfs4_purge_state_owners(server); + nfs4_purge_state_owners(server, &freeme); + nfs4_free_state_owners(&freeme); } /* --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -598,24 +598,39 @@ void nfs4_put_state_owner(struct nfs4_st /** * nfs4_purge_state_owners - Release all cached state owners * @server: nfs_server with cached state owners to release + * @head: resulting list of state owners * * Called at umount time. Remaining state owners will be on * the LRU with ref count of zero. + * Note that the state owners are not freed, but are added + * to the list @head, which can later be used as an argument + * to nfs4_free_state_owners. */ -void nfs4_purge_state_owners(struct nfs_server *server) +void nfs4_purge_state_owners(struct nfs_server *server, struct list_head *head) { struct nfs_client *clp = server->nfs_client; struct nfs4_state_owner *sp, *tmp; - LIST_HEAD(doomed); spin_lock(&clp->cl_lock); list_for_each_entry_safe(sp, tmp, &server->state_owners_lru, so_lru) { - list_move(&sp->so_lru, &doomed); + list_move(&sp->so_lru, head); nfs4_remove_state_owner_locked(sp); } spin_unlock(&clp->cl_lock); +} + +/** + * nfs4_purge_state_owners - Release all cached state owners + * @head: resulting list of state owners + * + * Frees a list of state owners that was generated by + * nfs4_purge_state_owners + */ +void nfs4_free_state_owners(struct list_head *head) +{ + struct nfs4_state_owner *sp, *tmp; - list_for_each_entry_safe(sp, tmp, &doomed, so_lru) { + list_for_each_entry_safe(sp, tmp, head, so_lru) { list_del(&sp->so_lru); nfs4_free_state_owner(sp); } @@ -1719,12 +1734,13 @@ static int nfs4_do_reclaim(struct nfs_cl struct nfs4_state_owner *sp; struct nfs_server *server; struct rb_node *pos; + LIST_HEAD(freeme); int status = 0; restart: rcu_read_lock(); list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) { - nfs4_purge_state_owners(server); + nfs4_purge_state_owners(server, &freeme); spin_lock(&clp->cl_lock); for (pos = rb_first(&server->state_owners); pos != NULL; @@ -1752,6 +1768,7 @@ restart: spin_unlock(&clp->cl_lock); } rcu_read_unlock(); + nfs4_free_state_owners(&freeme); return 0; }