From: NeilBrown neilb@suse.de
[ 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 neilb@suse.de Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sunrpc/sched.c | 4 +++- net/sunrpc/xprtrdma/transport.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 8fc4a6b3422f..32ffa801a5b9 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -1039,8 +1039,10 @@ int rpc_malloc(struct rpc_task *task) struct rpc_buffer *buf; gfp_t gfp = GFP_NOFS;
+ if (RPC_IS_ASYNC(task)) + gfp = GFP_NOWAIT | __GFP_NOWARN; if (RPC_IS_SWAPPER(task)) - gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN; + gfp |= __GFP_MEMALLOC;
size += sizeof(struct rpc_buffer); if (size <= RPC_BUFFER_MAXSIZE) diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index 2f21e3c52bfc..866bcd99bdc0 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -626,8 +626,10 @@ xprt_rdma_allocate(struct rpc_task *task) gfp_t flags;
flags = RPCRDMA_DEF_GFP; + if (RPC_IS_ASYNC(task)) + flags = GFP_NOWAIT | __GFP_NOWARN; if (RPC_IS_SWAPPER(task)) - flags = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN; + flags |= __GFP_MEMALLOC;
if (!rpcrdma_check_regbuf(r_xprt, req->rl_sendbuf, rqst->rq_callsize, flags))