linux-kernel - Re: [patch 1/3] mmu

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]

Message-ID: <Pine.LNX.4.64.0801311901580.6272@schroedinger.engr.sgi.com>
Date:	Thu, 31 Jan 2008 19:03:43 -0800 (PST)
From:	Christoph Lameter <clameter@....com>
To:	Jack Steiner <steiner@....com>
cc:	Robin Holt <holt@....com>, Andrea Arcangeli <andrea@...ranet.com>,
	Avi Kivity <avi@...ranet.com>, Izik Eidus <izike@...ranet.com>,
	kvm-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com
Subject: Re: [patch 1/3] mmu_notifier: Core code

On Thu, 31 Jan 2008, Jack Steiner wrote:

> I currently unlink the mmu_notifier when the last GRU mapping is closed. For
> example, if a user does a:
> 
>         gru_create_context();
>         ...
>         gru_destroy_context();
> 
> the mmu_notifier is unlinked and all task tables allocated
> by the driver are freed. Are you suggesting that I leave tables
> allocated until the task terminates??

You are in user space and calling into the kernel somehow. The 
mmap_sem is not held at that point so its no trouble to use the unregister 
function. After that wait for rcu and then free your tables.

> I assumed that I would need to use call_rcu() or synchronize_rcu()
> before the table is actually freed. That's still on my TODO list.

Right.

--
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/