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Bug#452931: marked as done (linux-image-2.6.18-5-686: too much memory for EXT3 inode-cache in slab)

Your message dated Sat, 25 Jul 2009 16:01:30 +0200
with message-id <20090725140130.GA28550@galadriel.inutil.org>
and subject line Re: linux-image-2.6.18-5-686: too much memory for EXT3 inode-cache in slab
has caused the Debian Bug report #452931,
regarding linux-image-2.6.18-5-686: too much memory for EXT3 inode-cache in slab
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

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-- 
452931: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=452931
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: linux-image-2.6.18-5-686
Version: 2.6.18.dfsg.1-13etch4
Severity: important

On two very different systems (a desktop system and one running a
database application) running debian kernel 2.6.18-5 I'm observing the
following behaviour:

System accumulates *large* amounts of slab-memory in EXT3 Inode-Cache,
example-output from the command "slabtop":

 Active / Total Objects (% used)    : 1559187 / 1578880 (98.8%)
 Active / Total Slabs (% used)      : 135874 / 135878 (100.0%)
 Active / Total Caches (% used)     : 94 / 140 (67.1%)
 Active / Total Size (% used)       : 529040.32K / 531151.94K (99.6%)
 Minimum / Average / Maximum Object : 0.01K / 0.34K / 128.00K

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
907400 905957  99%    0.49K 113425        8    453700K ext3_inode_cache
565964 565089  99%    0.13K  19516       29     78064K dentry_cache
 62064  56390  90%    0.05K    862       72      3448K buffer_head
  7756   7752  99%    0.27K    554       14      2216K radix_tree_node
  6313   2673  42%    0.06K    107       59       428K size-64

As you can see, this system has accumulated more that 400MB of
Slab-Memory (on a system with 1GB of memory, i.e. half of the whole
memory of the system just for caching inodes!). This memory is not
freed, even in an out-of-memory situation, the system rather invokes the
out-of-memory-killer (OOM-Killer) before freeing this memory.

The only way I can reclaim this memory is running

echo 2 > /proc/sys/vm/drop_caches

After issuing this command, slab-usage goes back to sane values:

 Active / Total Objects (% used)    : 87942 / 117616 (74.8%)
 Active / Total Slabs (% used)      : 3532 / 3542 (99.7%)
 Active / Total Caches (% used)     : 96 / 140 (68.6%)
 Active / Total Size (% used)       : 10961.59K / 13940.84K (78.6%)
 Minimum / Average / Maximum Object : 0.01K / 0.12K / 128.00K

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
 61632  52088  84%    0.05K    856       72      3424K buffer_head
  8874   2227  25%    0.13K    306       29      1224K dentry_cache
  8302   7748  93%    0.27K    593       14      2372K radix_tree_node
  6254   2533  40%    0.06K    106       59       424K size-64
  3780   3752  99%    0.04K     45       84       180K sysfs_dir_cache
  2806   2790  99%    0.08K     61       46       244K vm_area_struct
  2712   2647  97%    0.03K     24      113        96K size-32
  2028    892  43%    0.02K     12      169        48K dm_io
  1696    568  33%    0.49K    212        8       848K ext3_inode_cache

On the desktop-system the time until the inode-cache is using so much
memory takes several days. On the database server I'm doing a nightly
backup that copies 200000 files -- after the copying the inode-cache is
using more than 400MB of memory as in the above output of slabtop.

Is this a bug present in upstream-kernels too or something seen only in
debians build?

Is anybody else seeing this?

-- System Information:
Debian Release: 4.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-5-686
Locale: LANG=en_US.ISO-8859-15, LC_CTYPE=en_US.ISO-8859-15 (charmap=ISO-8859-15)

Versions of packages linux-image-2.6.18-5-686 depends on:
ii  coreutils                     5.97-5.3   The GNU core utilities
ii  debconf [debconf-2.0]         1.5.11     Debian configuration management sy
ii  initramfs-tools [linux-initra 0.85h      tools for generating an initramfs
ii  module-init-tools             3.3-pre4-2 tools for managing Linux kernel mo

Versions of packages linux-image-2.6.18-5-686 recommends:
pn  libc6-i686                    <none>     (no description available)

-- debconf information:
  linux-image-2.6.18-5-686/postinst/create-kimage-link-2.6.18-5-686: true
  linux-image-2.6.18-5-686/postinst/old-system-map-link-2.6.18-5-686: true
  linux-image-2.6.18-5-686/preinst/elilo-initrd-2.6.18-5-686: true
  linux-image-2.6.18-5-686/postinst/bootloader-test-error-2.6.18-5-686:
  linux-image-2.6.18-5-686/postinst/depmod-error-2.6.18-5-686: false
* linux-image-2.6.18-5-686/preinst/already-running-this-2.6.18-5-686:
  linux-image-2.6.18-5-686/preinst/bootloader-initrd-2.6.18-5-686: true
  linux-image-2.6.18-5-686/postinst/old-dir-initrd-link-2.6.18-5-686: true
  linux-image-2.6.18-5-686/postinst/old-initrd-link-2.6.18-5-686: true
  linux-image-2.6.18-5-686/preinst/failed-to-move-modules-2.6.18-5-686:
  linux-image-2.6.18-5-686/preinst/abort-install-2.6.18-5-686:
  linux-image-2.6.18-5-686/prerm/would-invalidate-boot-loader-2.6.18-5-686: true
  linux-image-2.6.18-5-686/postinst/bootloader-error-2.6.18-5-686:
  linux-image-2.6.18-5-686/preinst/lilo-initrd-2.6.18-5-686: true
  linux-image-2.6.18-5-686/preinst/overwriting-modules-2.6.18-5-686: true
  shared/kernel-image/really-run-bootloader: true
  linux-image-2.6.18-5-686/postinst/depmod-error-initrd-2.6.18-5-686: false
  linux-image-2.6.18-5-686/prerm/removing-running-kernel-2.6.18-5-686: true
  linux-image-2.6.18-5-686/preinst/initrd-2.6.18-5-686:
  linux-image-2.6.18-5-686/preinst/lilo-has-ramdisk:
  linux-image-2.6.18-5-686/postinst/kimage-is-a-directory:
  linux-image-2.6.18-5-686/preinst/abort-overwrite-2.6.18-5-686:

--- End Message ---
--- Begin Message --- 
On Sat, Nov 22, 2008 at 02:31:06PM +0100, Moritz Muehlenhoff wrote:
> On Mon, Nov 26, 2007 at 09:08:19AM +0100, Ralf Schlatterbeck wrote:
> > Package: linux-image-2.6.18-5-686
> > Version: 2.6.18.dfsg.1-13etch4
> > Severity: important
> > 
> > On two very different systems (a desktop system and one running a
> > database application) running debian kernel 2.6.18-5 I'm observing the
> > following behaviour:
> 
> Does this error still occur with more recent kernel versions?
> 
> If you're running Etch, could you try to reproduce this bug
> with the 2.6.24 based kernel added in 4.0r4?
> http://packages.qa.debian.org/l/linux-2.6.24.html


No further feedback, closing the bug.

If anyone reencounters the problem, please reopen this bug.

Cheers,
        Moritz

--- End Message ---
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