From: Chuck Lever chuck.lever@oracle.com

Jan Schunk reports that his small NFS servers suffer from memory exhaustion after just a few days. A bisect shows that commit e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_sendmsg() call") is the first bad commit.

That commit assumed that sock_sendmsg() releases all the pages in the underlying bio_vec array, but the reality is that it doesn't. svc_xprt_release() releases the rqst's response pages, but the record marker page fragment isn't one of those, so it is never released.

This is a narrow fix that can be applied to stable kernels. A more extensive fix is in the works.

Reported-by: Jan Schunk scpcom@gmx.de Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218671 Fixes: e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_sendmsg() call") Cc: Alexander Duyck alexander.duyck@gmail.com Cc: Jakub Kacinski kuba@kernel.org Cc: David Howells dhowells@redhat.com Reviewed-by: David Howells dhowells@redhat.com Signed-off-by: Chuck Lever chuck.lever@oracle.com --- net/sunrpc/svcsock.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c index e0ce42762..933e12e3a 100644 --- a/net/sunrpc/svcsock.c +++ b/net/sunrpc/svcsock.c @@ -1216,15 +1216,6 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp) * MSG_SPLICE_PAGES is used exclusively to reduce the number of * copy operations in this path. Therefore the caller must ensure * that the pages backing @xdr are unchanging. - * - * Note that the send is non-blocking. The caller has incremented - * the reference count on each page backing the RPC message, and - * the network layer will "put" these pages when transmission is - * complete. - * - * This is safe for our RPC services because the memory backing - * the head and tail components is never kmalloc'd. These always - * come from pages in the svc_rqst::rq_pages array. */ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp, rpc_fraghdr marker, unsigned int *sentp) @@ -1254,6 +1245,7 @@ static int svc_tcp_sendmsg(struct svc_sock *svsk, struct svc_rqst *rqstp, iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, rqstp->rq_bvec, 1 + count, sizeof(marker) + rqstp->rq_res.len); ret = sock_sendmsg(svsk->sk_sock, &msg); + page_frag_free(buf); if (ret < 0) return ret; *sentp += ret;