It's possible that we could race with a call to xs_reset_transport, in which case the xprt->inet pointer could be zeroed out while we're accessing it. Lock the xprt before we try to set memalloc on it.
Cc: Mel Gorman <[email protected]> Signed-off-by: Jeff Layton <[email protected]> --- net/sunrpc/xprtsock.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 359446442112..91770ccab608 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1964,11 +1964,22 @@ static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task) } #ifdef CONFIG_SUNRPC_SWAP +/* + * Note that this should be called with XPRT_LOCKED held (or when we otherwise + * know that we have exclusive access to the socket), to guard against + * races with xs_reset_transport. + */ static void xs_set_memalloc(struct rpc_xprt *xprt) { struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + /* + * If there's no sock, then we have nothing to set. The + * reconnecting process will get it for us. + */ + if (!transport->inet) + return; if (atomic_read(&xprt->swapper)) sk_set_memalloc(transport->inet); } @@ -1986,8 +1997,11 @@ xs_swapper_enable(struct rpc_xprt *xprt) struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE)) + return -ERESTARTSYS; if (atomic_inc_return(&xprt->swapper) == 1) sk_set_memalloc(transport->inet); + xprt_release_xprt(xprt, NULL); return 0; } @@ -2004,8 +2018,11 @@ xs_swapper_disable(struct rpc_xprt *xprt) struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE)) + return; if (atomic_dec_and_test(&xprt->swapper)) sk_clear_memalloc(transport->inet); + xprt_release_xprt(xprt, NULL); } #else static void xs_set_memalloc(struct rpc_xprt *xprt) -- 2.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
