On Sat, Feb 09, 2008 at 06:09:23PM +0100, Thomas Gleixner wrote: > On Sat, 9 Feb 2008, Andi Kleen wrote: > > > > Note the behaviour for pageattr and thus DEBUG_RODATA / debugging > > > > sitations where you don't care about your TLB this > > > > does not change, this makes only a difference for the initial init_32 > > > > direct mapping setup. > > > > > > Your patches do change the behaviour. The range checking breaks the > > > enforcement of some restrictions for the sake of keeping the large > > > page intact. > > > > You mean in try_preserve_large_page()? > > > > No actually they were not completely enforced previously at all, because > > it did only check the restrictions of the first page. > > Right, you poked my nose to it. I did not think about it when I coded > it. It is wrong and needs to be fixed, but not by the range check you > introduced.
Well I need the range check for a different piece of code (init_memory_mapping()) For that a range check is definitely needed and the existing code there also does an (although quite fishy) range check. The DEBUG_RODATA case is also handled correctly there because DEBUG_RODATA is applied explicitely using pageattr later. You have not commented on that at all so I assume it's ok for you. > > On the end of my patch series the enforcement is actually stricter > > than it was before, although not 100%. > > As far as I can tell it is more relaxed, as it will make overlapping > regions of rodata and rwdata completely rw instead of splitting it up. In try_preserve_large_page()? No because it only checks the first page. In all other cases (in the existing code; my patchkit adds a new case in mm/init_32.c) it always only checks single 4K pages so the only overlap case would be sub 4K. For that there can be no split up. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
