Its possible that using AUTH_SYS and mountd manage-gids option a user may hit the 8k RPC channel buffer limit. This have been observed on field, causing unanswered RPCs on clients after mountd fails to write on channel : rpc.mountd[11231]: auth_unix_gid: error writing reply Userland nfs-utils uses a buffer size of 32k (RPC_CHAN_BUF_SIZE), so lets match those two. Signed-off-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx> --- net/sunrpc/cache.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index baef5ee43dbb..08df4c599ab3 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -908,7 +908,7 @@ static ssize_t cache_do_downcall(char *kaddr, const char __user *buf, static ssize_t cache_slow_downcall(const char __user *buf, size_t count, struct cache_detail *cd) { - static char write_buf[8192]; /* protected by queue_io_mutex */ + static char write_buf[32768]; /* protected by queue_io_mutex */ ssize_t ret = -EINVAL; if (count >= sizeof(write_buf)) -- 2.21.0