Messages in this thread | | | From | Nick Piggin <> | Subject | Re: [patch 1/5] vmalloc: do not check for freed locks on user maps | Date | Thu, 6 Mar 2008 09:56:43 +1100 |
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On Thursday 06 March 2008 04:20, Thomas Gleixner wrote: > On Thu, 6 Mar 2008, Nick Piggin wrote: > > On Thursday 06 March 2008 03:03, Thomas Gleixner wrote: > > > User maps do not contain kernel internal objects. No need to check > > > them. > > > > Why not? Depends on your definition of kernel internal... and > > objects ;) > > > > Drivers could create and manage some objects in this vmalloc > > area. They are no longer internal if you map them to userspace, > > but I still don't think you want to vunmap it until those > > object lifetimes are finished. > > Well, in case of the locks I have a hard time to figure out how you > use a spinlock/mutex with a user space address. The same applies for > timers or other objects used by kernel subsystems. So when the driver > writer creates an kernel related object in the vmalloc space, he has > to use the kernel mapping which is unmapped separate, right ?
This is the kernel mapping. The user mapping is unmapped when the userspace munmaps.
> I can see your concern about the infinite stu^H^H^Hcreativity of > driver writers, but I prefer not to go down that road and provide > debug infrastructure for absurdities.
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