DR> That's not a precedent, there's a big difference between the
DR> performance of gup_fast(), where we can't spare an additional
DR> compare and branch, and walk_page_range().  VM_BUG_ON() is typically
DR> used in situations where a debug kernel has been built, including
DR> CONFIG_DEBUG_VM, and the check helps to isolate a problem that would
DR> be otherwise difficult to find.

Okay, fair enough. I was trying to stay in line with the other
conventions, knowing that the check would only be done with
CONFIG_DEBUG_VM enabled.

I'd rather just make it always do the check in walk_page_range(). Does
that sound reasonable?

-- 
Dan Smith
IBM Linux Technology Center
email: danms@us.ibm.com

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