On 09/09/2012 06:56 PM, H. Peter Anvin wrote: >> >> Anyway, that means that the BUG_ON() is likely bogus, but so is the >> whole calling convention. >> >> The 4kB range starting at 0xfffffffffffff000 sounds like a *valid* >> range, but that requires that we fix the calling convention to not >> have that "end" (exclusive) thing. It should either be "end" >> (inclusive), or just "len". >> > > On x86, it is definitely NOT a valid range. There is no physical addresses > there, and there will never be any. This reminds me a similar issue: If you try to mmap /dev/kmem at an offset which is not kernel owned (such as 0), you'll get all the way to __pa() before getting a BUG() about addresses not making sense. How come there's no arch-specific validation of attempts to access virtual/physical addresses? In the kmem example I'd assume that something very early on should be yelling at me about doing something like that, but for some reason I get all the way to __pa() before getting a BUG() (!). Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>