BMC/Intel-BMC/linux.git/net/sunrpc, branch dev-5.15-intel

SUNRPC: Fix NFSD's request deferral on RDMA transports

2022-04-20T07:34:18+00:00

commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 upstream. Trond Myklebust reports an NFSD crash in svc_rdma_sendto(). Further investigation shows that the crash occurred while NFSD was handling a deferred request. This patch addresses two inter-related issues that prevent request deferral from working correctly for RPC/RDMA requests: 1. Prevent the crash by ensuring that the original svc_rqst::rq_xprt_ctxt value is available when the request is revisited. Otherwise svc_rdma_sendto() does not have a Receive context available with which to construct its reply. 2. Possibly since before commit 71641d99ce03 ("svcrdma: Properly compute .len and .buflen for received RPC Calls"), svc_rdma_recvfrom() did not include the transport header in the returned xdr_buf. There should have been no need for svc_defer() and friends to save and restore that header, as of that commit. This issue is addressed in a backport-friendly way by simply having svc_rdma_recvfrom() set rq_xprt_hlen to zero unconditionally, just as svc_tcp_recvfrom() does. This enables svc_deferred_recv() to correctly reconstruct an RPC message received via RPC/RDMA. Reported-by: Trond Myklebust Link: https://lore.kernel.org/linux-nfs/82662b7190f26fb304eb0ab1bb04279072439d4e.camel@hammerspace.com/ Signed-off-by: Chuck Lever Cc: Signed-off-by: Greg Kroah-Hartman

SUNRPC: Don't call connect() more than once on a TCP socket

2022-04-13T18:59:26+00:00

commit 89f42494f92f448747bd8a7ab1ae8b5d5520577d upstream. Avoid socket state races due to repeated calls to ->connect() using the same socket. If connect() returns 0 due to the connection having completed, but we are in fact in a closing state, then we may leave the XPRT_CONNECTING flag set on the transport. Reported-by: Enrico Scholz Fixes: 3be232f11a3c ("SUNRPC: Prevent immediate close+reconnect") Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman

SUNRPC: Prevent immediate close+reconnect

2022-04-13T18:59:24+00:00

commit 3be232f11a3cc9b0ef0795e39fa11bdb8e422a06 upstream. If we have already set up the socket and are waiting for it to connect, then don't immediately close and retry. Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman

SUNRPC: svc_tcp_sendmsg() should handle errors from xdr_alloc_bvec()

2022-04-13T18:59:20+00:00

[ Upstream commit b056fa070814897be32d83b079dbc311375588e7 ] The allocation is done with GFP_KERNEL, but it could still fail in a low memory situation. Fixes: 4a85a6a3320b ("SUNRPC: Handle TCP socket sends with kernel_sendpage() again") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC: Handle low memory situations in call_status()

2022-04-13T18:59:20+00:00

[ Upstream commit 9d82819d5b065348ce623f196bf601028e22ed00 ] We need to handle ENFILE, ENOBUFS, and ENOMEM, because xprt_wake_pending_tasks() can be called with any one of these due to socket creation failures. Fixes: b61d59fffd3e ("SUNRPC: xs_tcp_connect_worker{4,6}: merge common code") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC: Handle ENOMEM in call_transmit_status()

2022-04-13T18:59:20+00:00

[ Upstream commit d3c15033b240767d0287f1c4a529cbbe2d5ded8a ] Both call_transmit() and call_bc_transmit() can now return ENOMEM, so let's make sure that we handle the errors gracefully. Fixes: 0472e4766049 ("SUNRPC: Convert socket page send code to use iov_iter()") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC: Fix socket waits for write buffer space

2022-04-13T18:59:13+00:00

[ Upstream commit 7496b59f588dd52886fdbac7633608097543a0a5 ] The socket layer requires that we use the socket lock to protect changes to the sock->sk_write_pending field and others. Reported-by: Chuck Lever Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC: remove scheduling boost for "SWAPPER" tasks.

2022-04-13T18:59:12+00:00

[ Upstream commit a80a8461868905823609be97f91776a26befe839 ] Currently, tasks marked as "swapper" tasks get put to the front of non-priority rpc_queues, and are sorted earlier than non-swapper tasks on the transport's ->xmit_queue. This is pointless as currently *all* tasks for a mount that has swap enabled on *any* file are marked as "swapper" tasks. So the net result is that the non-priority rpc_queues are reverse-ordered (LIFO). This scheduling boost is not necessary to avoid deadlocks, and hurts fairness, so remove it. If there were a need to expedite some requests, the tk_priority mechanism is a more appropriate tool. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC/xprt: async tasks mustn't block waiting for memory

2022-04-13T18:59:12+00:00

[ Upstream commit a721035477fb5fb8abc738fbe410b07c12af3dc5 ] When memory is short, new worker threads cannot be created and we depend on the minimum one rpciod thread to be able to handle everything. So it must not block waiting for memory. xprt_dynamic_alloc_slot can block indefinitely. This can tie up all workqueue threads and NFS can deadlock. So when called from a workqueue, set __GFP_NORETRY. The rdma alloc_slot already does not block. However it sets the error to -EAGAIN suggesting this will trigger a sleep. It does not. As we can see in call_reserveresult(), only -ENOMEM causes a sleep. -EAGAIN causes immediate retry. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC/call_alloc: async tasks mustn't block waiting for memory

2022-04-13T18:59:12+00:00

[ Upstream commit c487216bec83b0c5a8803e5c61433d33ad7b104d ] When memory is short, new worker threads cannot be created and we depend on the minimum one rpciod thread to be able to handle everything. So it must not block waiting for memory. mempools are particularly a problem as memory can only be released back to the mempool by an async rpc task running. If all available workqueue threads are waiting on the mempool, no thread is available to return anything. rpc_malloc() can block, and this might cause deadlocks. So check RPC_IS_ASYNC(), rather than RPC_IS_SWAPPER() to determine if blocking is acceptable. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin