Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id

[Oleg Nesterov]

On 04/14, Peter Zijlstra wrote:
>
> On Fri, 2012-04-06 at 00:20 +0200, Oleg Nesterov wrote:
> > Hello.
> >
> > Not for inclusion yet, only for the early review.
> >
> > I didn't even try to test these changes, and I am not expert
> > in this area. And even _if_ this code is correct, I need to
> > re-split these changes anyway, update the changelogs, etc.
> >
> > Questions:
> >
> > 	- does it make sense?
>
> Maybe, upside is reclaiming that int from task_struct, downside is that
> down_write :/ It would be very good not to have to do that.

Yes, down_write() is pessimization, I agree.

> Nor do I
> really see how that works.
>
> > 	- can it work or I missed something "in general" ?
>
> So we insert in the rb-tree before we take mmap_sem, this means we can
> hit a non-uprobe int3 and still find a uprobe there, no?

Yes, but unless I miss something this is "off-topic", this
can happen with or without these changes. If find_uprobe()
succeeds we assume that this bp was inserted by uprobe.

Perhaps uprobe_register() should not "ignore" -EXIST from
install_breakpoint()->is_swbp_insn(), or perhaps we can
add UPROBE_SHARED_BP.

Oleg.

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