From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nigel Cunningham <nigel@nigel.suspend2.net>
Subject: Re: [PATCH] Remove process freezer from suspend to RAM
	pathway
Date: Fri, 6 Jul 2007 19:16:16 +1000
Message-ID: <200707061916.17590.nigel@nigel.suspend2.net>
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To: Miklos Szeredi <miklos@szeredi.hu>
Cc: mjg59@srcf.ucam.org, nigel@suspend2.net, linux-kernel@vger.kernel.org, pavel@ucw.cz, linux-pm@lists.linux-foundation.org
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Hi.

On Friday 06 July 2007 19:09:43 Miklos Szeredi wrote:
> > > > Moreover, if FUSE implements syncing, then the sync from within the=
=20
freezer
> > > > will almost certainly deadlock.
> > >=20
> > > Rafael, think positively: by the time fuse implements sync(), the
> > > freezer will be long gone ;)
> >=20
> > Now you are entering really dangerous territory.
> > If you can implement a meaningfull sync method, you must have dirty
> > pages in the page cache. That means you are in the page freeing path
> > of the vm. Then we are in real trouble. Don't even think about it.
>=20
> VM induced deadlocks are real nasty.  I have thought about them a lot
> already.  Suspend shouldn't introduce any big surprises.

Suspend isn't introducing the surprises. Fuse is. It creates the potential=
=20
deadlocks simply by existing (this isn't suspend or hibernate specific).

Nigel

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