Re: [tip:perf/core] x86, 64-bit: Fix copy_[to/from]_user() checks forthe userspace address limit

From: Linus Torvalds
Date: Wed May 18 2011 - 16:55:12 EST


On Wed, May 18, 2011 at 1:43 PM, tip-bot for Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> As reported in BZ #30352:
>
>  https://bugzilla.kernel.org/show_bug.cgi?id=30352
>
> there's a kernel bug related to reading the last allowed page on x86_64.

Btw, I think this message is very misleading.

It has nothing what-so-ever to do with "the last allowed page".

It is not about pages at all. It's about bytes. It's the very last
byte of the address space. The fact that the *test*program* uses mmap
and then sends a single page is totally irrelevant both for the kernel
and for the patch itself.

Linus
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