Messages in this thread | | | Subject | Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id | From | Peter Zijlstra <> | Date | Mon, 23 Apr 2012 09:40:42 +0200 |
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On Mon, 2012-04-23 at 12:54 +0530, Srikar Dronamraju wrote: > * Peter Zijlstra <peterz@infradead.org> [2012-04-23 09:14:00]: > > > On Fri, 2012-04-20 at 20:37 +0200, Oleg Nesterov wrote: > > > Say, a user wants to probe /sbin/init only. What if init forks? > > > We should remove breakpoints from child->mm somehow. > > > > How is that hard? dup_mmap() only copies the VMAs, this doesn't actually > > copy the breakpoint. So the child doesn't have a breakpoint to be > > removed. > > > > Because the pages are COWED, the breakpoint gets copied over to the > child. If we dont want the breakpoints to be not visible to the child, > then we would have to remove them explicitly based on the filter (i.e if > and if we had inserted breakpoints conditionally based on filter).
I thought we didn't COW shared maps since the fault handler will fill in the pages right and only anon stuff gets copied.
> Once we add the conditional breakpoint insertion (which is tricky),
How so?
> we have > to support conditional breakpoint removal in the dup_mmap() thro the > uprobe_mmap hook (which I think is not that hard). Conditional removal > of breakpoints in fork path would just be an extension of the > conditional breakpoint insertion.
Right, I don't think that removal is particularly hard if needed.
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