linux-kernel - inotify_add_watch() returning ENOSPC in 2.6.24 [watch descriptor leak?]

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Date:	Tue, 5 Feb 2008 20:49:42 -0500
From:	"Clem Taylor" <clem.taylor@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: inotify_add_watch() returning ENOSPC in 2.6.24 [watch descriptor leak?]

I'm trying to move a MIPS based embedded system from 2.6.16.16 to
2.6.24. Most things seem to be working, but I'm having troubles with
inotify. The code is using inotify to detect a file written to /tmp
(tmpfs). The writer creates a file with a temporary name and then
rename()s the tmp file over the file I'm monitoring.

With 2.6.16.16, everything works fine, but with 2.6.24, the inotify
process runs for a while (~100 events) and then inotify_add_watch()
returns ENOSPC. Once this happens, I can't add new watches, even if I
kill the process and restart it. fs.inotify.max_user_instances and
fs.inotify.max_user_watches are both 128, so I'd imagine I'm hitting
this limit. For some reason the watches aren't getting cleaned up
(even after the process is killed).

In a loop, the code is doing:
    wd = inotify_add_watch(fd, file, IN_CLOSE_WRITE|IN_DELETE_SELF|IN_ONESHOT);
    blocking read on notify fd

Has something changed in the inotify() API since 2.6.16.16, or could
this be a leak?

                                      --Clem
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