On Fri, Feb 11, 2011 at 11:58:58AM -0800, Hugh Dickins wrote: > Oh, I hadn't realized Fedora use it. I wonder if that's wise, I thought > Nick introduced it partly for the more expensive checks, and there might > be one or two of those around - those bad_range()s in page_alloc.c? I doubt the more expensive checks are very measurable.. benchmarks usually run on enterprise distro. I'm sure when they enabled, they were aware of having to run more expensive runtime checks. > But the patch actually says -1024*1024: either would do. I actually increased it to -1024*1024 after writing the email ;) sorry the for the confusion. > Yes, that's fine, 0xfff00000 looks unlikely enough (and my > imagination for "deadbeef"-like magic is too drowsy today). I used a negative power of two even if I doubt the compiler can make much use of it. > Okay I suppose: it seems rather laboured to me, I think I'd have just > moved the VM_BUG_ON into rmv_page_order() if I'd done the patch; but > since I was too lazy to do it, I'd better be grateful for yours! Ok the reason I didn't move the VM_BUG_ON is to be stricter in case there are more usages of __ClearPageBuddy in the future. I guess it's not so important, but when I initially implemented it, it wasn't entirely obvious it would work safe with memory hotplug, compaction and all other bits using PageBuddy, so... -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>