Messages in this thread | | | Subject | Re: BUG: mmapfile/writev spurious zero bytes (x86_64/not i386, bisected, reproducable) | From | Andi Kleen <> | Date | Tue, 17 Jun 2008 22:58:17 +0200 |
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Linus Torvalds <torvalds@linux-foundation.org> writes:
> > So I'm starting to think the bug is all in there, not in the VM itself. > See arch/x86/lib/copy_user_nocache.S.
The x86-64 copy_*_user functions were always designed to return errors both ways (as in both for load and for store). That's needed because the loops are shared for copy_to_user and copy_from_user. That's normally ok because when you do _to_user you shouldn't fault on the loads and vice versa. If a caller does that it's buggy.
-Andi
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