linux-kernel - Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway

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Date:	Sat, 7 Jul 2007 14:17:29 +0200
From:	Pavel Machek <pavel@....cz>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	oliver@...kum.org, paulus@...ba.org, stern@...land.harvard.edu,
	johannes@...solutions.net, rjw@...k.pl,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	mjg59@...f.ucam.org, benh@...nel.crashing.org
Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway

Hi!

> > > Actually fuse allows SIGKILL, because it's always fatal, and the
> > > syscall may not be restarted.
> > 
> > I think you want to stick try_to_freeze() at the same places where you
> > do SIGKILL handling. That should solve the 'syslogd is unfreezeable'
> > problem.
> 
> I could, but it would not solve the general problem.  Namely, that the
> presence of fuse imposes a certain ordering in which userspace tasks
> have to be frozen.  And it is not possible to know this ordering.

We can just wait for all fuse requests to be serviced before
proceeding further with freeze, right?

> And even if the ordering were solved, the freezer would still not work
> if the filesystem is not responding due to external events, such as a
> lost network (this affects NFS, CIFS, whatever just the same as
> fuse).

That's ok, you can't suspend if your hdd is dead, and in the same way
you can't suspend if your NFS server is dead. I agree it is ugly, but
we seem to live ok with that.

We could (and should?) handle that, probably by realizing that NFS is
not a disk and using interruptible sleep, but...

> > Plus, it would be nice to find out where suspend/hibernation is
> > triggering fuse activity. We can then decide where to fix it -- in
> > fuse or in suspend parts. You said sys_sync is not implemented... so
> > where is the problem?
> 
> I cannot say without having a sysrq-t of the situation.

Yes please. Can someone affected please produce sysrq-t?
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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