Subject: Concurrency issue in /proc?
From: Patrick LeBoutillier <patrick.leboutillier@gmail.com>
Date: Tue, 29 Jun 2010 08:17:01 -0400

 Tue, 29 Jun 2010 08:17:01 -0400
Hi all,

I'm running kernel 2.6.32.6 with patch 2.3.0.36.28 and I think there's
a concurrency issue in the /proc /filesystem.
Don't know if that makes a difference, but I'm also using Jacques' tools.

On a multicore (8 cores) server, if I run the following script:

while /bin/true ; do
        ls -ld /proc/self > /dev/null
done

twice in parallel (i.e. sh test.sh & sh test.sh) inside a guest, I get
a lot of errors like this:

ls: cannot read symbolic link /proc/self: No such file or directory
ls: cannot read symbolic link /proc/self: No such file or directory
ls: /proc/self: No such file or directory
ls: cannot read symbolic link /proc/self: No such file or directory
ls: cannot read symbolic link /proc/self: No such file or directory
ls: cannot read symbolic link /proc/self: No such file or directory
ls: /proc/self: No such file or directory

However, if I run the same script directly in the root server, I can't
reproduce the issue.

Here's how the various procs are mounted:
none on /proc type proc (rw)                       # root /proc
none on /vtmp/test/proc type proc (rw)         # guest /proc

Does anyone have a clue on how to fix this? I looked at the patch, but
it's a bit out of
my league...


Thanks,

Patrick

-- 
=====================
Patrick LeBoutillier
Rosemère, Québec, Canada