Re: [Bugme-new] [Bug 12754] New: inotify doesn't free memory allocated to watches

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 24 Feb 2009 23:23:37 +0000
Al Viro <viro@ZenIV.linux.org.uk> wrote:

> On Tue, Feb 24, 2009 at 09:38:00PM +0000, Al Viro wrote:
> > On Tue, Feb 24, 2009 at 01:05:23PM -0800, Andrew Morton wrote:
> > 
> > > > We have webcams that take photos every 5 minutes.  I run a daemon
> > > > that detects the creation of a new webcam photo then makes a thumbnail
> > > > of it.  Eventually it stopped working.  I figured out that I could
> > > > not create new watches:  inotify_add_watch reported "No space left on device".
> > > > I create all the watches with the ONESHOT parameter so they are deleted
> > > > as soon as they are triggered.  When I make it display the watch number
> > > > it's always 3.  A new watch is added only when the old watch has been
> > > > triggered.  inotify isn't recovering the memory from deleted watches.
> 
> IN_ONESHOT means that they will be *removed* as they are triggered.  You still
> have to call put_inotify_watch() from your ->handle_event() when you get
> IN_ONESHOT in the mask.  IOW, check your ->handle_event(); unless it does
> that put_inotify_watch(), you are leaking.

y:/usr/src/linux-2.6.29-rc6> grep -rl inotify_operations .
./Documentation/filesystems/inotify.txt
./kernel/audit.c
./kernel/audit_tree.c
./fs/notify/inotify/inotify_user.c
./fs/notify/inotify/inotify.c
./include/linux/inotify.h

I assume it's inotify_dev_queue_event()?

        if (mask & IN_IGNORED || w->mask & IN_ONESHOT)
                put_inotify_watch(w); /* final put */