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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 5 Jul 2007 10:24:22 +0200
From:	Oliver Neukum <oliver@...kum.org>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	paulus@...ba.org, stern@...land.harvard.edu,
	johannes@...solutions.net, rjw@...k.pl,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	pavel@....cz, mjg59@...f.ucam.org, benh@...nel.crashing.org
Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway

Am Donnerstag, 5. Juli 2007 schrieb Miklos Szeredi:
> > > > I have discussed the benefits elsewhere.  As for the deadlocks -- do 
> > > > you still observe them if you use the version of the freezer which 
> > > > doesn't freeze kernel threads?
> > > 
> > > In general the only way to guarantee there are no deadlocks is to
> > > construct the graph of dependencies between tasks.  Those dependencies
> > > are not in practice observable from outside the tasks, so it is
> > > virtually impossible to construct the graph.
> > 
> > In which way can user space tasks depend on each other in a way that
> > allows a them members of that cycle to be in uninterruptible sleep?
> 
>  - process A calls rename() on a fuse fs
>  - process B, the fuse server, starts to process the rename request
>  - process B is frozen before it can reply
> 
> Now process A is unfreezable.  We cannot make rename() restartable,
> hence it cannot be interruptible.

Then this is a problem specific to fuse. You should teach fuse to block
suspension while such operations are being performed.

	Regards
		Oliver

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/