Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932840AbcDKN66 (ORCPT ); Mon, 11 Apr 2016 09:58:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:37403 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932325AbcDKNXy (ORCPT ); Mon, 11 Apr 2016 09:23:54 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jeff Layton , Jeff Layton , Trond Myklebust , Jiri Slaby Subject: [PATCH 3.12 29/98] nfs: fix high load average due to callback thread sleeping Date: Mon, 11 Apr 2016 15:22:31 +0200 Message-Id: X-Mailer: git-send-email 2.8.1 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2200 Lines: 61 From: Jeff Layton 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 5d05e54af3cdbb13cf19c557ff2184781b91a22c upstream. Chuck pointed out a problem that crept in with commit 6ffa30d3f734 (nfs: don't call blocking operations while !TASK_RUNNING). Linux counts tasks in uninterruptible sleep against the load average, so this caused the system's load average to be pinned at at least 1 when there was a NFSv4.1+ mount active. Not a huge problem, but it's probably worth fixing before we get too many complaints about it. This patch converts the code back to use TASK_INTERRUPTIBLE sleep, simply has it flush any signals on each loop iteration. In practice no one should really be signalling this thread at all, so I think this is reasonably safe. With this change, there's also no need to game the hung task watchdog so we can also convert the schedule_timeout call back to a normal schedule. Reported-by: Chuck Lever Signed-off-by: Jeff Layton Tested-by: Chuck Lever Fixes: commit 6ffa30d3f734 (“nfs: don't call blocking . . .”) Signed-off-by: Trond Myklebust Signed-off-by: Jiri Slaby --- fs/nfs/callback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index f4cac2b06ac3..50443e6dc033 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -128,7 +128,7 @@ nfs41_callback_svc(void *vrqstp) if (try_to_freeze()) continue; - prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_UNINTERRUPTIBLE); + prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE); spin_lock_bh(&serv->sv_cb_lock); if (!list_empty(&serv->sv_cb_list)) { req = list_first_entry(&serv->sv_cb_list, @@ -142,10 +142,10 @@ nfs41_callback_svc(void *vrqstp) error); } else { spin_unlock_bh(&serv->sv_cb_lock); - /* schedule_timeout to game the hung task watchdog */ - schedule_timeout(60 * HZ); + schedule(); finish_wait(&serv->sv_cb_waitq, &wq); } + flush_signals(current); } return 0; } -- 2.8.1