linux-kernel - Re: [RFC][PATCH -mm] Freezer: Handle uninterruptible tasks

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Date:	Sat, 7 Jul 2007 13:31:18 +0200
From:	Pavel Machek <pavel@....cz>
To:	nigel@...pend2.net
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	LKML <linux-kernel@...r.kernel.org>,
	Oliver Neukum <oliver@...kum.org>,
	Miklos Szeredi <miklos@...redi.hu>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC][PATCH -mm] Freezer: Handle uninterruptible tasks

Hi!

> > I don't think we can do that. I suspect rename looks like:
> > 
> > 	write directory entry in source
> > A)	(uninterruptible wait for write)
> > 	write directory entry in destination
> > 	(uninterruptible wait for write)
> > 	write something else
> > 
> > If we freeze some task in place "A)", we'll write to the disk when the
> > directory write is finished :-(.
> 
> Renaming is a single syscall, so won't the process get frozen when the syscall 
> finishes? 

It would be frozen when syscall finishes. But if we freeze it at A)
point, we have a problem.

> Perhaps you've just found more logic for keeping the sys_sync there?

No, I don't think so.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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