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H A Ddlmrecovery.c30bee898 Thu Jan 14 17:17:18 CST 2016 Xue jiufei <xuejiufei@huawei.com> 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 <xuejiufei@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
30bee898 Thu Jan 14 17:17:18 CST 2016 Xue jiufei <xuejiufei@huawei.com> 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 <xuejiufei@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>