On Mon, 13 Feb 2012, Dan Smith wrote: > DR> It doesn't "ensure" anything without CONFIG_DEBUG_VM enabled, which > DR> isn't the default. > > Are you proposing a change in verbiage or a stronger check? A > VM_BUG_ON() seemed on par with other checks, such as the one in > get_user_pages_fast(). > That's not a precedent, there's a big difference between the performance of gup_fast(), where we can't spare an additional compare and branch, and walk_page_range(). VM_BUG_ON() is typically used in situations where a debug kernel has been built, including CONFIG_DEBUG_VM, and the check helps to isolate a problem that would be otherwise difficult to find. If that fits the criteria, fine, but it doesn't "ensure" walk_page_range() always has start and end addresses that are page aligned, so the changelog needs to be modified to describe why an error in this path wouldn't be evident. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>