From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f72.google.com (mail-vk0-f72.google.com [209.85.213.72]) by kanga.kvack.org (Postfix) with ESMTP id 97F9A6B026C for ; Mon, 9 Oct 2017 06:44:27 -0400 (EDT) Received: by mail-vk0-f72.google.com with SMTP id h63so14620516vka.10 for ; Mon, 09 Oct 2017 03:44:27 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 16sor170428iot.94.2017.10.09.03.44.23 for (Google Transport Security); Mon, 09 Oct 2017 03:44:23 -0700 (PDT) MIME-Version: 1.0 From: Yafang Shao Date: Mon, 9 Oct 2017 18:44:23 +0800 Message-ID: Subject: Re: [PATCH] mm/page-writeback.c: fix bug caused by disable periodic writeback Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Andrew Morton , mhocko@suse.com, Johannes Weiner , vdavydov.dev@gmail.com, jlayton@redhat.com, nborisov@suse.com, Theodore Ts'o , mawilcox@microsoft.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, axboe@kernel.dk 2017-10-09 17:56 GMT+08:00 Jan Kara : > On Sat 07-10-17 06:58:04, Yafang Shao wrote: >> After disable periodic writeback by writing 0 to >> dirty_writeback_centisecs, the handler wb_workfn() will not be >> entered again until the dirty background limit reaches or >> sync syscall is executed or no enough free memory available or >> vmscan is triggered. >> So the periodic writeback can't be enabled by writing a non-zero >> value to dirty_writeback_centisecs >> As it can be disabled by sysctl, it should be able to enable by >> sysctl as well. >> >> Signed-off-by: Yafang Shao >> --- >> mm/page-writeback.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/mm/page-writeback.c b/mm/page-writeback.c >> index 0b9c5cb..e202f37 100644 >> --- a/mm/page-writeback.c >> +++ b/mm/page-writeback.c >> @@ -1972,7 +1972,13 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb) >> int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, >> void __user *buffer, size_t *length, loff_t *ppos) >> { >> - proc_dointvec(table, write, buffer, length, ppos); >> + unsigned int old_interval = dirty_writeback_interval; >> + int ret; >> + >> + ret = proc_dointvec(table, write, buffer, length, ppos); >> + if (!ret && !old_interval && dirty_writeback_interval) >> + wakeup_flusher_threads(0, WB_REASON_PERIODIC); >> + > > I agree it is good to schedule some writeback. However Jens has some > changes queued in linux-block tree in this area so your change won't apply. > So please base your changes on his tree. > Do you mean this tree git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git ? I have checked his tree and find nothing need to change on my patch. > Honza > -- > Jan Kara > SUSE Labs, CR Thanks Yafang -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org