[RFC] fs, proc: Introduce the /proc/<pid>/map_files/ directory v2

Cyrill Gorcunov gorcunov at gmail.com
Wed Aug 24 08:22:22 PDT 2011


On Wed, Aug 24, 2011 at 09:05:21AM -0600, Zan Lynx wrote:
> On 8/24/2011 2:53 AM, Cyrill Gorcunov wrote:
> > From: Pavel Emelyanov <xemul at parallels.com>
> > 
> > This one behaves similarly to the /proc/<pid>/fd/ one - it contains symlinks
> > one for each mapping with file, the name of a symlink is vma->vm_start, the
> > target is the file. Opening a symlink results in a file that point exactly
> > to the same inode as them vma's one.
> > 
> > This thing is aimed to help checkpointing processes.
> > 
> > For example the ls -l of some arbitrary /proc/<pid>/map_files/
> > 
> >  | lr-x------ 1 cyrill cyrill 64 Aug  9 15:25 0x3d73a00000 -> /lib64/ld-2.5.so
> [snip]
> 
> Just curious: How do these symlinks work when the process reading a
> /proc file is in a chroot or a different namespace?
> 
> For example, a chroot environment might have independent copies of
> /lib64/ld-2.5.so and a bind mount of /proc. Does the symlink then point
> to the wrong file?

To be fair, I personally didn't tried such scenario but it should be
the same behaviour as for /proc/$pid/fd since data is taken from
a task pointed by pid. I'll check though, good question.

	Cyrill


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