Re: possible (ext4 related?) memory leak in kernel 2.6.26

[ Reply-to set to linux-ext4@xxxxxxxxxxxxxxx ]

On Tue, Sep 30, 2008 at 10:27:29PM +0200, Quentin Godfroy wrote:
Hi lists,
I'd like to report the following problem : after ~ 10 days' uptime on a
Debian 2.6.26-1-686 kernel, my system becomes extremely sluggish and
unresponsive and the OOM-killer starts targeting even innocent processes like
identd or rsync (when the swap is disabled). The machine is low on RAM (192
MB) but this has never been a problem before. As for the slowness, strace
shows that the brk() syscall takes ages to complete; the blocking processes
are in the D state (and for some reason the kernel gives no wchan info).

Config has nothing unusual except that all fs are ext4, which I am begining
to suspect may be the culprit, as every night some process stat()s and
read()s something like 850,000 files, which is maybe fs-stressing; also,
umounting then remounting /home makes the 'buffers' drop from 127304 to
55920 and partially solves the problem.

Free reports a large and constantly growing 'buffers' figure (more than
50% of the available memory). No userland processes seems to be consuming
lare amounts of memory (sum of RSS in 'ps aux' is about 30 megs), and the
overall system is mostly idle.

for instance, the following command reports

$ free ; dpkg -l '*' >/dev/null; dmesg | tail -n 2
total used free shared buffers cached
Mem: 190356 178920 11436 0 126104 12520
-/+ buffers/cache: 40296 150060
Swap: 0 0 0
/* Waits a minute or so */
Killed
[811245.911859] Out of memory: kill process 6639 (dpkg-query) score 7292 or a child
[811245.911972] Killed process 6639 (dpkg-query)


Can you send the output of /proc/meminfo and /proc/slabinfo?

- Ted
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