From mboxrd@z Thu Jan 1 00:00:00 1970 From: piaojun Date: Fri, 22 Jun 2018 08:34:14 +0800 Subject: [Ocfs2-devel] [PATCH] ocfs2: Fix locking for res->tracking and dlm->tracking_list In-Reply-To: <1529625429-13901-1-git-send-email-ashish.samant@oracle.com> References: <1529625429-13901-1-git-send-email-ashish.samant@oracle.com> Message-ID: <5B2C4406.7030500@huawei.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com Hi Ashish, I think we should get 'res->spinlock' before getting 'dlm->track_lock' such as in __dlm_do_purge_lockres(). But your patch reverse the locking sequence as we will get 'res->spinlock' in dlm_print_one_lock_resource() which may cause 'ABBA' deadlock. thanks, Jun On 2018/6/22 7:57, Ashish Samant wrote: > In dlm_init_lockres() and dlm_unregister_domain() we access and modify > res->tracking and dlm->tracking_list without holding dlm->track_lock. > This can cause list corruptions and can end up in kernel panic. > > Fix this by locking res->tracking and dlm->tracking_list with > dlm->track_lock at all places. > > Signed-off-by: Ashish Samant > --- > fs/ocfs2/dlm/dlmdomain.c | 2 ++ > fs/ocfs2/dlm/dlmmaster.c | 4 ++-- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c > index 2acd58b..cfb1edd 100644 > --- a/fs/ocfs2/dlm/dlmdomain.c > +++ b/fs/ocfs2/dlm/dlmdomain.c > @@ -723,6 +723,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm) > mlog(0, "%s: more migration to do\n", dlm->name); > } > > + spin_lock(&dlm->track_lock); > /* This list should be empty. If not, print remaining lockres */ > if (!list_empty(&dlm->tracking_list)) { > mlog(ML_ERROR, "Following lockres' are still on the " > @@ -730,6 +731,7 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm) > list_for_each_entry(res, &dlm->tracking_list, tracking) > dlm_print_one_lock_resource(res); > } > + spin_unlock(&dlm->track_lock); > > dlm_mark_domain_leaving(dlm); > dlm_leave_domain(dlm); > diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c > index aaca094..826f056 100644 > --- a/fs/ocfs2/dlm/dlmmaster.c > +++ b/fs/ocfs2/dlm/dlmmaster.c > @@ -584,9 +584,9 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm, > > res->last_used = 0; > > - spin_lock(&dlm->spinlock); > + spin_lock(&dlm->track_lock); > list_add_tail(&res->tracking, &dlm->tracking_list); > - spin_unlock(&dlm->spinlock); > + spin_unlock(&dlm->track_lock); > > memset(res->lvb, 0, DLM_LVB_LEN); > memset(res->refmap, 0, sizeof(res->refmap)); >