Messages in this thread | | | Date | Fri, 06 Nov 2009 17:24:16 +0900 | From | Tejun Heo <> | Subject | Re: irq lock inversion |
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Hello, Ingo.
Ingo Molnar wrote: > I havent looked deeply but at first sight i'm not 100% sure that even > the lock dance hack is safe - doesnt vfree() do TLB flushes, which must > be done with irqs enabled in general? If yes, then the whole notion of > using the allocator from irqs-off sections is wrong and the flags > save/restore is misguided (or at least incomplete).
The only place where any v*() call is nested under pcpu_lock is in the alloc path, specifically pcpu_extend_area_map() ends up calling vfree(). pcpu_free() path which can be called from irq context never calls any vmalloc function directly. The reclaiming is deferred to a work. Breaking the single nesting completely decouples the two locks and nobody would be calling vfree() with irq disabled, so I don't think there will be any problem.
Thanks.
-- tejun
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