Re: [PATCH] uprobes: Skip breakpoint installation on non executable vmas

On Thu, Aug 6, 2026 at 8:35 AM Oleg Nesterov [off-list ref] wrote:

On 08/06, Sumanth Korikkar wrote:

quoted

On Thu, Aug 06, 2026 at 01:01:11PM +0200, Oleg Nesterov wrote:

quoted

But your change in install_breakpoint() essentually reverts that commit?
If uprobe_register() -> register_for_each_vma() finds a VM_MAYEXEC vma
without VM_EXEC valid_vma() will return true, but then install_breakpoint()
will fail anyway.

Initially non exec vma will be ignored via uprobe_register(),
install_breakpoint() will reject non vma mappings initially.

As far as I understand,  if mprotect(PROT_EXEC) is performed later by a
process, it adds VM_EXEC flag to vma and calls vma_complete() via
vma_modify_flags(). uprobe_mmap() will then call install_breakpoint()
and now it should succeed because VM_EXEC is set.

Heh, I am stupid the 2nd time in the same thread ;)

Sumanth, thanks for correcting me! It seems that I forgot everything about
these code paths.

Then this change makes more sense, but the VM_EXEC check needs the comment
to explain this all.

However, I personally still don't think it's worth "fixing". But I leave the
decision to Andrii and Jiri who (unlike me) understand how USDT's are used.

I agree, I don't see what needs to be fixed here.

Oleg.