linux-kernel - Re: [PATCH v3 04/16] lockdep: check that no locks held at freeze time

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20130507122906.GC2585@elf.ucw.cz>
Date:	Tue, 7 May 2013 14:29:07 +0200
From:	Pavel Machek <pavel@....cz>
To:	Colin Cross <ccross@...roid.com>
Cc:	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mandeep Singh Baines <msb@...omium.org>,
	Oleg Nesterov <oleg@...hat.com>, linux-nfs@...r.kernel.org,
	linux-pm@...r.kernel.org, netdev@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Ben Chan <benchan@...omium.org>,
	Len Brown <len.brown@...el.com>
Subject: Re: [PATCH v3 04/16] lockdep: check that no locks held at freeze time

On Mon 2013-05-06 16:50:09, Colin Cross wrote:
> From: Mandeep Singh Baines <msb@...omium.org>
> 
> We shouldn't try_to_freeze if locks are held.  Holding a lock can cause a
> deadlock if the lock is later acquired in the suspend or hibernate path
> (e.g.  by dpm).  Holding a lock can also cause a deadlock in the case of
> cgroup_freezer if a lock is held inside a frozen cgroup that is later
> acquired by a process outside that group.
> 
> History:
> This patch was originally applied as 6aa9707099c and reverted in
> dbf520a9d7d4 because NFS was freezing with locks held.  It was
> deemed better to keep the bad freeze point in NFS to allow laptops
> to suspend consistently.  The previous patch in this series converts
> NFS to call _unsafe versions of the freezable helpers so that
> lockdep doesn't complain about them until a more correct fix
> can be applied.
> 
> [akpm@...ux-foundation.org: export debug_check_no_locks_held]
> Signed-off-by: Mandeep Singh Baines <msb@...omium.org>
> Cc: Ben Chan <benchan@...omium.org>
> Cc: Oleg Nesterov <oleg@...hat.com>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Rafael J. Wysocki <rjw@...k.pl>
> Cc: Ingo Molnar <mingo@...hat.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> [ccross@...roid.com: don't warn if try_to_freeze_unsafe is called]
> Signed-off-by: Colin Cross <ccross@...roid.com>

Acked-by: Pavel Machek <pavel@....cz>

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