Hi Ravi,
On 08/06, Ravi Bangoria wrote:
>
> >> +static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm)
> >> +{
> >> + struct delayed_uprobe *du;
> >> +
> >> + if (delayed_uprobe_check(uprobe, mm))
> >> + return 0;
> >> +
> >> + du = kzalloc(sizeof(*du), GFP_KERNEL);
> >> + if (!du)
> >> + return -ENOMEM;
> >> +
> >> + du->uprobe = uprobe;
> >> + du->mm = mm;
> >
> > I am surprised I didn't notice this before...
> >
> > So
> > du->mm = mm;
> >
> > is fine, mm can't go away, uprobe_clear_state() does
> > delayed_uprobe_remove(NULL,mm).
> >
> > But
> > du->uprobe = uprobe;
> >
> > doesn't look right, uprobe can go away and it can be freed, its memory can
> > be reused.
> > We can't rely on remove_breakpoint(),
>
>
> I'm sorry. I didn't get this. How can uprobe go away without calling
> uprobe_unregister()
> -> rergister_for_each_vma()
> -> remove_breakpoint()
> And remove_breakpoint() will get called
assuming that _unregister() will find the same vma with the probed insn. But
as I said, the application can munmap the probed page/vma.
No?
> > Also. delayed_uprobe_add() should check the list and avoid duplicates.
> > Otherwise the
> > trivial
> >
> > for (;;)
> > munmap(mmap(uprobed_file));
> >
> > will eat the memory until uprobe is unregistered.
>
>
> I'm already calling delayed_uprobe_check(uprobe, mm) from
> delayed_uprobe_add().
Oops ;)
Oleg.
