From 30bee898f86506893883ffb8db20d8101a29b5f5 Mon Sep 17 00:00:00 2001 From: Xue jiufei Date: Thu, 14 Jan 2016 15:17:18 -0800 Subject: [PATCH] ocfs2/dlm: fix a race between purge and migration We found a race between purge and migration when doing code review. Node A put lockres to purgelist before receiving the migrate message from node B which is the master. Node A call dlm_mig_lockres_handler to handle this message. dlm_mig_lockres_handler dlm_lookup_lockres >>>>>> race window, dlm_run_purge_list may run and send deref message to master, waiting the response spin_lock(&res->spinlock); res->state |= DLM_LOCK_RES_MIGRATING; spin_unlock(&res->spinlock); dlm_mig_lockres_handler returns >>>>>> dlm_thread receives the response from master for the deref message and triggers the BUG because the lockres has the state DLM_LOCK_RES_MIGRATING with the following message: dlm_purge_lockres:209 ERROR: 6633EB681FA7474A9C280A4E1A836F0F: res M0000000000000000030c0300000000 in use after deref Signed-off-by: Jiufei Xue Reviewed-by: Joseph Qi Reviewed-by: Yiwen Jiang Cc: Mark Fasheh Cc: Joel Becker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/dlm/dlmrecovery.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c index 9e4f862d20fe..86fb53614bf4 100644 --- a/fs/ocfs2/dlm/dlmrecovery.c +++ b/fs/ocfs2/dlm/dlmrecovery.c @@ -1373,6 +1373,7 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data, char *buf = NULL; struct dlm_work_item *item = NULL; struct dlm_lock_resource *res = NULL; + unsigned int hash; if (!dlm_grab(dlm)) return -EINVAL; @@ -1400,7 +1401,10 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data, /* lookup the lock to see if we have a secondary queue for this * already... just add the locks in and this will have its owner * and RECOVERY flag changed when it completes. */ - res = dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len); + hash = dlm_lockid_hash(mres->lockname, mres->lockname_len); + spin_lock(&dlm->spinlock); + res = __dlm_lookup_lockres(dlm, mres->lockname, mres->lockname_len, + hash); if (res) { /* this will get a ref on res */ /* mark it as recovering/migrating and hash it */ @@ -1421,13 +1425,16 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data, mres->lockname_len, mres->lockname); ret = -EFAULT; spin_unlock(&res->spinlock); + spin_unlock(&dlm->spinlock); dlm_lockres_put(res); goto leave; } res->state |= DLM_LOCK_RES_MIGRATING; } spin_unlock(&res->spinlock); + spin_unlock(&dlm->spinlock); } else { + spin_unlock(&dlm->spinlock); /* need to allocate, just like if it was * mastered here normally */ res = dlm_new_lockres(dlm, mres->lockname, mres->lockname_len); -- 2.20.1