Re: [RFC PATCH v2 1/2] mm/mremap: Fix uprobe anon page be overwritten when expanding vma during mremap

[Oleg Nesterov <oleg@redhat.com>]

Hi Lehui,

On 05/28, Pu Lehui wrote:
>
> On 2025/5/27 22:23, Oleg Nesterov wrote:
> >Well, I leave this to you / Lorenzo / David, but...
> >
> >On 05/27, Pu Lehui wrote:
> >>
> >>Fixes: 78a320542e6c ("uprobes: Change valid_vma() to demand VM_MAYEXEC rather than VM_EXEC")
> >
> >I don't think that commit could cause this problem.
>
> Hi Oleg,
>
> Me too! I was test that before and after commit 78a320542e6c, so call it the
> `directly related commit`.

I feel I am totally confused...

but _may be_ you have used the initial reproducer which used PROT_NONE in

	void *addr2 = mmap(NULL, 2 * 4096, PROT_NONE, MAP_PRIVATE, fd, 0);

?

If yes. I _think_ we should have the same problem with or without 78a320542e6c,
just you need to s/PROT_NONE/PROT_EXEC/.

> In fact, I think the issue was introduced in the
> original commit 2b1444983508 ("uprobes, mm, x86: Add the ability to install
> and remove uprobes breakpoints") # v3.5-rc1.

probably yes... Damn I don't know ;)

Oleg.