Re: [tip:locking/urgent] locking/mutex: Disable optimistic spinning on some architectures

[Davidlohr Bueso]

On Wed, 2014-07-16 at 12:24 -0700, tip-bot for Peter Zijlstra wrote:
> Commit-ID:  4badad352a6bb202ec68afa7a574c0bb961e5ebc
> Gitweb:     http://git.kernel.org/tip/4badad352a6bb202ec68afa7a574c0bb961e5ebc
> Author:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> AuthorDate: Fri, 6 Jun 2014 19:53:16 +0200
> Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Wed, 16 Jul 2014 14:57:07 +0200
> 
> locking/mutex: Disable optimistic spinning on some architectures
> 
> The optimistic spin code assumes regular stores and cmpxchg() play nice;
> this is found to not be true for at least: parisc, sparc32, tile32,
> metag-lock1, arc-!llsc and hexagon.
> 
> There is further wreckage, but this in particular seemed easy to
> trigger, so blacklist this.
> 
> Opt in for known good archs.
> 
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Reported-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Cc: David Miller <davem@xxxxxxxxxxxxx>
> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
> Cc: Jason Low <jason.low2@xxxxxx>
> Cc: Waiman Long <waiman.long@xxxxxx>
> Cc: "James E.J. Bottomley" <jejb@xxxxxxxxxxxxxxxx>
> Cc: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Cc: John David Anglin <dave.anglin@xxxxxxxx>
> Cc: James Hogan <james.hogan@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Davidlohr Bueso <davidlohr@xxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> Cc: sparclinux@xxxxxxxxxxxxxxx
> Link: http://lkml.kernel.org/r/20140606175316.GV13930@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>

Cc'ing stable: this issue was reported to begin after commit fb0527bd,
so since v3.13.

Thanks,
Davidlohr

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