Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755491Ab1BVWd6 (ORCPT ); Tue, 22 Feb 2011 17:33:58 -0500 Received: from kroah.org ([198.145.64.141]:46664 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754172Ab1BVWVb (ORCPT ); Tue, 22 Feb 2011 17:21:31 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Feb 22 14:18:39 2011 Message-Id: <20110222221839.164753186@clark.kroah.org> User-Agent: quilt/0.48-11.2 Date: Tue, 22 Feb 2011 14:17:00 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Dave Chinner , Arkadiusz Miskiewicz Subject: [21/70] xfs: fix dquot shaker deadlock In-Reply-To: <20110222222003.GA15831@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4173 Lines: 149 2.6.37-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dave Chinner commit 0fbca4d1c3932c27c4794bf5c2b5fc961cf5a54f upstream. Commit 368e136 ("xfs: remove duplicate code from dquot reclaim") fails to unlock the dquot freelist when the number of loop restarts is exceeded in xfs_qm_dqreclaim_one(). This causes hangs in memory reclaim. Rework the loop control logic into an unwind stack that all the different cases jump into. This means there is only one set of code that processes the loop exit criteria, and simplifies the unlocking of all the items from different points in the loop. It also fixes a double increment of the restart counter from the qi_dqlist_lock case. Reported-by: Malcolm Scott Signed-off-by: Dave Chinner Reviewed-by: Alex Elder Cc: Arkadiusz Miskiewicz Signed-off-by: Greg Kroah-Hartman --- fs/xfs/quota/xfs_qm.c | 46 +++++++++++++++++++++------------------------- 1 file changed, 21 insertions(+), 25 deletions(-) --- a/fs/xfs/quota/xfs_qm.c +++ b/fs/xfs/quota/xfs_qm.c @@ -1863,12 +1863,14 @@ xfs_qm_dqreclaim_one(void) xfs_dquot_t *dqpout; xfs_dquot_t *dqp; int restarts; + int startagain; restarts = 0; dqpout = NULL; /* lockorder: hashchainlock, freelistlock, mplistlock, dqlock, dqflock */ -startagain: +again: + startagain = 0; mutex_lock(&xfs_Gqm->qm_dqfrlist_lock); list_for_each_entry(dqp, &xfs_Gqm->qm_dqfrlist, q_freelist) { @@ -1885,13 +1887,10 @@ startagain: ASSERT(! (dqp->dq_flags & XFS_DQ_INACTIVE)); trace_xfs_dqreclaim_want(dqp); - - xfs_dqunlock(dqp); - mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock); - if (++restarts >= XFS_QM_RECLAIM_MAX_RESTARTS) - return NULL; XQM_STATS_INC(xqmstats.xs_qm_dqwants); - goto startagain; + restarts++; + startagain = 1; + goto dqunlock; } /* @@ -1906,23 +1905,20 @@ startagain: ASSERT(list_empty(&dqp->q_mplist)); list_del_init(&dqp->q_freelist); xfs_Gqm->qm_dqfrlist_cnt--; - xfs_dqunlock(dqp); dqpout = dqp; XQM_STATS_INC(xqmstats.xs_qm_dqinact_reclaims); - break; + goto dqunlock; } ASSERT(dqp->q_hash); ASSERT(!list_empty(&dqp->q_mplist)); /* - * Try to grab the flush lock. If this dquot is in the process of - * getting flushed to disk, we don't want to reclaim it. + * Try to grab the flush lock. If this dquot is in the process + * of getting flushed to disk, we don't want to reclaim it. */ - if (!xfs_dqflock_nowait(dqp)) { - xfs_dqunlock(dqp); - continue; - } + if (!xfs_dqflock_nowait(dqp)) + goto dqunlock; /* * We have the flush lock so we know that this is not in the @@ -1944,8 +1940,7 @@ startagain: xfs_fs_cmn_err(CE_WARN, mp, "xfs_qm_dqreclaim: dquot %p flush failed", dqp); } - xfs_dqunlock(dqp); /* dqflush unlocks dqflock */ - continue; + goto dqunlock; } /* @@ -1967,13 +1962,8 @@ startagain: */ if (!mutex_trylock(&mp->m_quotainfo->qi_dqlist_lock)) { restarts++; - mutex_unlock(&dqp->q_hash->qh_lock); - xfs_dqfunlock(dqp); - xfs_dqunlock(dqp); - mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock); - if (restarts++ >= XFS_QM_RECLAIM_MAX_RESTARTS) - return NULL; - goto startagain; + startagain = 1; + goto qhunlock; } ASSERT(dqp->q_nrefs == 0); @@ -1986,14 +1976,20 @@ startagain: xfs_Gqm->qm_dqfrlist_cnt--; dqpout = dqp; mutex_unlock(&mp->m_quotainfo->qi_dqlist_lock); +qhunlock: mutex_unlock(&dqp->q_hash->qh_lock); dqfunlock: xfs_dqfunlock(dqp); +dqunlock: xfs_dqunlock(dqp); if (dqpout) break; if (restarts >= XFS_QM_RECLAIM_MAX_RESTARTS) - return NULL; + break; + if (startagain) { + mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock); + goto again; + } } mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock); return dqpout; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/