Re: Unexpected behaviour of idr_get_empty_slot() on parisc

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Fri, 2010-01-15 at 10:26 -0600, James Bottomley wrote:
> On Sun, 2010-01-03 at 18:50 -0500, Kyle McMartin wrote:
> > On Sun, Jan 03, 2010 at 11:23:25PM +0000, Ben Hutchings wrote:
> > > Ryan Niebur reported in <http://bugs.debian.org/561880> that on a
> > > PA-RISC system running Linux 2.6.32 the following test case for inotify:
> > > 
> > 
> > I bet this is because classic RCU is removed, and tree RCU was
> > insufficiently tested on crap platforms before the removal.
> > 
> > I'll try to re-add it and we can see if it's an RCU problem or something
> > nastier.
> 
> Apparently it's a feature of kernels beyond 2.6.30 (this exact
> behaviour).  Suspect the bug report is incomplete and the i386 machine
> was running 2.6.29 or lower.
> 
> Red Hat has been getting complaints about it so they're looking to
> revert to the old 2.6.29 behaviour as well.  The actual commit that
> caused the behaviour change is
> 
> commit 63c882a05416e18de6fb59f7dd6da48f3bbe8273
> Author: Eric Paris <eparis@redhat.com>
> Date:   Thu May 21 17:02:01 2009 -0400
> 
>     inotify: reimplement inotify using fsnotify

Just to close this out, the fix (for all architectures) is now upstream:

commit 9e572cc9877ee6c43af60778f6b8d5ba0692d935
Author: Eric Paris <eparis@redhat.com>
Date:   Fri Jan 15 12:12:24 2010 -0500

    inotify: do not reuse watch descriptors

James