Re: [PATCH] Fix do_mlock so page alignment is to hugepage boundries when needed

On Wed, 17 May 2006, Eric Paris wrote:

This patch still solves the problem of the kernel currently being more
restrictive on what we accept from userspace for the length of the mlock
if it is a hugepage rather than a regular page.  With a regular page we
will round the value from userspace and happily go about our business of
mlocking.  For a hugepage it just rejects it if userspace doesn't align
it themselves.  This allows the kernel to do the same work for hugepages
that it does for normal pages.

You do have a point that there's an inconsistency there.  But we could
argue a long time what's inconsistent with what - I'd say it's mlock
being inconsistent with mprotect, munmap, msync, madvise, etc.  I
don't see an outright reason to change from the current behaviour.

You do realize that there's almost no point in mlocking a hugepage area
anyway?  (I wrote that first without the "almost", but now with hugepage
faulting, it does provide another way to fault in all the pages at once.)

Hugh