lkml.org 
[lkml]   [2012]   [Apr]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id
From
Date
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.


\
 
 \ /
  Last update: 2012-04-23 09:47    [W:0.099 / U:0.648 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site