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| author | Chuck Lever <chuck.lever@oracle.com> | 2019-06-19 17:32:48 +0300 |
|---|---|---|
| committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2019-07-09 17:30:16 +0300 |
| commit | 05eb06d86685e7d9dac60e6bbb46d7f4c30b056e (patch) | |
| tree | 8f04bce3b88e16afd6912e44681b80752721c171 /security | |
| parent | 1310051c720a83c5717658bcbff710b260f2bff9 (diff) | |
| download | linux-05eb06d86685e7d9dac60e6bbb46d7f4c30b056e.tar.xz | |
xprtrdma: Fix occasional transport deadlock
Under high I/O workloads, I've noticed that an RPC/RDMA transport
occasionally deadlocks (IOPS goes to zero, and doesn't recover).
Diagnosis shows that the sendctx queue is empty, but when sendctxs
are returned to the queue, the xprt_write_space wake-up never
occurs. The wake-up logic in rpcrdma_sendctx_put_locked is racy.
I noticed that both EMPTY_SCQ and XPRT_WRITE_SPACE are implemented
via an atomic bit. Just one of those is sufficient. Removing
EMPTY_SCQ in favor of the generic bit mechanism makes the deadlock
un-reproducible.
Without EMPTY_SCQ, rpcrdma_buffer::rb_flags is no longer used and
is therefore removed.
Unfortunately this patch does not apply cleanly to stable. If
needed, someone will have to port it and test it.
Fixes: 2fad659209d5 ("xprtrdma: Wait on empty sendctx queue")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'security')
0 files changed, 0 insertions, 0 deletions