Re: [PATCH 01/12] uprobes: split THPs before trying replace them

From: Kirill A. Shutemov
Date: Tue Jan 24 2017 - 17:22:36 EST

On Tue, Jan 24, 2017 at 01:28:49PM -0800, Andrew Morton wrote:
> On Tue, 24 Jan 2017 19:28:13 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> > For THPs page_check_address() always fails. It's better to split them
> > first before trying to replace.
> So what does this mean. uprobes simply fails to work when trying to
> place a probe into a THP memory region?

Looks like we can end up with endless retry loop in uprobe_write_opcode().

> How come nobody noticed (and reported) this when using the feature?

I guess it's not often used for anon memory.

Kirill A. Shutemov