From a2f39fc0cdd1db20c4c4500224b83161c3549644 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 2 Jun 2022 01:48:55 +0000 Subject: [PATCH] SUNRPC/call_alloc: async tasks mustn't block waiting for memory stable inclusion from stable-4.19.238 commit 9970fca80164b3cbfd700acd735aa043d40a73ed category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5A6BA CVE: NA -------------------------------- [ 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 Signed-off-by: Yongqiang Liu --- 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 5af838a329e1..a873c92a4898 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -897,8 +897,10 @@ int rpc_malloc(struct rpc_task *task) struct rpc_buffer *buf; gfp_t gfp = GFP_NOIO | __GFP_NOWARN; + 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 bcac4bafa7c2..6be95ab8577d 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -647,8 +647,10 @@ 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_get_sendbuf(r_xprt, req, rqst->rq_callsize, flags)) goto out_fail; -- GitLab