After taking long time bisecting kernel (3.13 <-> 3.16) it came out that
the following commit (and its dependencies) are the ones that fixes the
issue:
commit b73c3adabdb1e2cb2f2c69bc3cbb9306aa3f9700
Author: Ariel Nahum <ari...@mellanox.com>
Date: Thu May 22 11:00:18 2014 +0300
IB/iser: Simplify connection management
iSER relies on refcounting to manage iser connections establishment
and teardown.
Following commit 39ff05dbbbdb ("IB/iser: Enhance disconnection logic
for multi-pathing"), iser connection maintain 3 references:
- iscsi_endpoint (at creation stage)
- cma_id (at connection request stage)
- iscsi_conn (at bind stage)
We can avoid taking explicit refcounts by correctly serializing iser
teardown flows (graceful and non-graceful).
Our approach is to trigger a scheduled work to handle ordered teardown
by gracefully waiting for 2 cleanup stages to complete:
1. Cleanup of live pending tasks indicated by iscsi_conn_stop completion
2. Flush errors processing
Each completed stage will notify a waiting worker thread when it is
done to allow teardwon continuation.
Since iSCSI connection establishment may trigger endpoint disconnect
without a successful endpoint connect, we rely on the iscsi <-> iser
binding (.conn_bind) to learn about the teardown policy we should take
wrt cleanup stages.
Since all cleanup worker threads are scheduled (release_wq) in
.ep_disconnect it is safe to assume that when module_exit is called,
all cleanup workers are already scheduled. Thus proper module unload
shall flush all scheduled works before allowing safe exit, to
guarantee no resources got left behind.
Signed-off-by: Ariel Nahum <ari...@mellanox.com>
Signed-off-by: Sagi Grimberg <sa...@mellanox.com>
Reviewed-by: Roi Dayan <r...@mellanox.com>
Reviewed-by: Or Gerlitz <ogerl...@mellanox.com>
Signed-off-by: Roland Dreier <rol...@purestorage.com>
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https://bugs.launchpad.net/bugs/1443648
Title:
Kernel panics on iSER (iscsi over IB) logouts
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