linux-kernel - Re: [PATCH/RFC] mutex: Fix optimistic spinning vs. BKL

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:	Wed, 28 Apr 2010 14:39:34 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Tony Breeds <tonyb@....ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH/RFC] mutex: Fix optimistic spinning vs. BKL

On Wed, 2010-04-28 at 14:38 +1000, Benjamin Herrenschmidt wrote:
> Currently, we can hit a nasty case with optimistic spinning on mutexes:
> 
>     CPU A tries to take a mutex, while holding the BKL
> 
>     CPU B tried to take the BLK while holding the mutex
> 
> This looks like a AB-BA scenario but in practice, is allowed and happens
> due to the auto-release-on-schedule nature of the BKL.

 .../...

BTW. The patch is only compile-tested so far :-) It's going to be
hammered with the test case that triggered the original bug hopefully
tonight.

Cheers,
Ben.


--
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/