From: Jan Kara <jack@suse.cz>
To: Tejun Heo <tj@kernel.org>
Cc: Jan Kara <jack@suse.cz>, Peter Chen <hzpeterchen@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>,
florian@mickler.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org,
usb-storage@lists.one-eyed-alien.net, Jan Kara <jack@suse.com>,
jkosina@suse.cz
Subject: Re: Freezable workqueue blocks non-freezable workqueue during the system resume process
Date: Mon, 14 Mar 2016 08:22:34 +0100 [thread overview]
Message-ID: <20160314072234.GC5213@quack.suse.cz> (raw)
In-Reply-To: <20160311175610.GL24046@htj.duckdns.org>
On Fri 11-03-16 12:56:10, Tejun Heo wrote:
> Hello, Jan.
>
> On Thu, Mar 03, 2016 at 10:33:10AM +0100, Jan Kara wrote:
> > > Ugh... that's nasty. I wonder whether the right thing to do is making
> > > writeback workers non-freezable. IOs are supposed to be blocked from
> > > lower layer anyway. Jan, what do you think?
> >
> > Well no, at least currently IO is not blocked in lower layers AFAIK - for
> > that you'd need to freeze block devices & filesystems and there are issues
>
> At least libata does and I think SCSI does too, but yeah, there
> probably are drivers which depend on block layer blocking IOs, which
> btw is a pretty fragile way to go about as upper layers might not be
> the only source of activities.
>
> > with that (Jiri Kosina was the last one which was trying to make this work
> > AFAIR). And I think you need to stop writeback (and generally any IO) to be
> > generated so that it doesn't interact in a strange way with device drivers
> > being frozen. So IMO until suspend freezes filesystems & devices properly
> > you have to freeze writeback workqueue.
>
> I still think the right thing to do is plugging that block layer or
> low level drivers. It's like we're trying to plug multiple sources
> when we can plug the point where they come together anyway.
I agree that freezing writeback workers is a workaround for real issues at
best and ideally we shouldn't have to do that. But at least for now I had
the impression that it is needed for suspend to work reasonably reliably.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2016-03-14 7:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-23 3:20 Freezable workqueue blocks non-freezable workqueue during the system resume process Peter Chen
2016-02-23 9:47 ` Peter Chen
2016-02-23 15:34 ` Alan Stern
2016-02-24 7:24 ` Peter Chen
2016-02-25 22:01 ` Tejun Heo
2016-02-26 6:19 ` Peter Chen
2016-03-02 16:00 ` Tejun Heo
2016-03-03 9:33 ` Jan Kara
2016-03-11 17:56 ` Tejun Heo
2016-03-14 7:22 ` Jan Kara [this message]
2016-03-14 14:37 ` Alan Stern
2016-03-15 9:25 ` Jan Kara
2016-03-16 15:00 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160314072234.GC5213@quack.suse.cz \
--to=jack@suse.cz \
--cc=florian@mickler.org \
--cc=hzpeterchen@gmail.com \
--cc=jack@suse.com \
--cc=jkosina@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=stern@rowland.harvard.edu \
--cc=tj@kernel.org \
--cc=usb-storage@lists.one-eyed-alien.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).