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slub: UML and CONFIG_CMPXCHG_LOCAL

DISCUSSION Richard Weinberger 2 participants 3 messages May 29, 2011 – May 31, 2011

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Christoph,

With commit 1759415e you've removed all #ifdef CONFIG_CMPXCHG_LOCAL's from slub. This change breaks slub (again) on UML.
UML does not implement this_cpu_cmpxchg16b_emu().

Starting with 2.6.39 (commit 084189a) I've disabled CONFIG_CMPXCHG_LOCAL on UML do bypass the issue. This fix does no longer help.

Is there anything I can do to have slub on UML? Implementing this_cpu_cmpxchg16b_emu for UML is not really an option. See:
http://comments.gmane.org/gmane.linux.kernel/1125183

Thanks,
//richard

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Quoted 3 lines · Richard Weinberger

With commit 1759415e you've removed all #ifdef CONFIG_CMPXCHG_LOCAL's from slub. This change breaks slub (again) on UML.
UML does not implement this_cpu_cmpxchg16b_emu().

It does not have to implement it. The this_cpu_ops can fall back to generic implementations.

Quoted 1 line

Is there anything I can do to have slub on UML?

Yes, rely on the generic implementation of this_cpu_cmpxchg.

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Am Dienstag 31 Mai 2011, 16:30:21 schrieb Christoph Lameter:

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Is there anything I can do to have slub on UML?

Yes, rely on the generic implementation of this_cpu_cmpxchg.

Thanks for the pointer.
You helped me a lot!

//richard