Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759481AbcCDJcp (ORCPT ); Fri, 4 Mar 2016 04:32:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:59691 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758985AbcCDJDT (ORCPT ); Fri, 4 Mar 2016 04:03:19 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jan Kara , Dmitry Vyukov , Al Viro , Jiri Slaby Subject: [PATCH 3.12 058/116] vfs: Avoid softlockups with sendfile(2) Date: Fri, 4 Mar 2016 10:01:43 +0100 Message-Id: X-Mailer: git-send-email 2.7.2 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1237 Lines: 42 From: Jan Kara 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit c2489e07c0a71a56fb2c84bc0ee66cddfca7d068 upstream. The following test program from Dmitry can cause softlockups or RCU stalls as it copies 1GB from tmpfs into eventfd and we don't have any scheduling point at that path in sendfile(2) implementation: int r1 = eventfd(0, 0); int r2 = memfd_create("", 0); unsigned long n = 1<<30; fallocate(r2, 0, 0, n); sendfile(r1, r2, 0, n); Add cond_resched() into __splice_from_pipe() to fix the problem. CC: Dmitry Vyukov Signed-off-by: Jan Kara Signed-off-by: Al Viro Signed-off-by: Jiri Slaby --- fs/splice.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/splice.c b/fs/splice.c index 76cb3a0b1ec4..76cbc01df6a4 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -949,6 +949,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, splice_from_pipe_begin(sd); do { + cond_resched(); ret = splice_from_pipe_next(pipe, sd); if (ret > 0) ret = splice_from_pipe_feed(pipe, sd, actor); -- 2.7.2