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On Mon, Mar 24, 2008 at 12:53:19PM -0700, Christoph Lameter wrote: > On Fri, 21 Mar 2008, Andi Kleen wrote: > > > The traditional reason this was discouraged (people seem to reinvent > > variants of this patch all the time) was that there used > > to be drivers that did __pa() (or equivalent) on stack addresses > > and that doesn't work with vmalloc pages. > > > > I don't know if such drivers still exist, but such a change > > is certainly not a no-brainer > > I thought that had been cleaned up because some arches already have Someone posted a patch recently that showed that the cdrom layer does it. Might be more. It is hard to audit a few million lines of driver code. > virtually mapped stacks? This could be debugged by testing with > CONFIG_VFALLBACK_ALWAYS set. Which results in a stack that is always > vmalloc'ed and thus the driver should fail. It might be a subtle failure. Maybe sparse could be taught to check for this if it happens in a single function? (cc'ing Al who might have some thoughts on this). Of course if it happens spread out over multiple functions sparse wouldn't help neither. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | |||||||||
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