Re: mdadm memory leak?

[David Kowis <dkowis@shlrm.org>]

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Neil Brown wrote:
>>  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME
>>152098 151909  99%    0.02K    673      226      2692K fasync_cache
>>24867  24846  99%    0.05K    307       81      1228K buffer_head
>>12432   8306  66%    0.27K    888       14      3552K radix_tree_node
>>  7308   6876  94%    0.13K    252       29      1008K dentry_cache
>>  6303   5885  93%    0.36K    573       11      2292K reiser_inode_cache
> 
> 
> So you have about 16 megabytes used by the slab cache, none of the big
> users 'md' related. 
> 16M doesn't sound like a big deal, so I suspect this isn't the source
> of the leak. 
>  From a separate Email I see:
> 
>>Mem:    773984k total,   765556k used,     8428k free,    65812k buffers
>>Swap:  2755136k total,        0k used,  2755136k free,   526632k cached
> 
> The fact that swap isn't being touched at all suggests that you aren't
> currently running low on memory.
> The fact the free is low doesn't directly indicate a problem.  Linux
> uses free memory to cache files.  It will discard then from the cache
> if it needs more memory.
> The fact that the OOM killer is hiting obviously is a problem.  Maybe
> you need to report this on linux-kernel was an OOM problem.
> 
I've let my computer run for a while longer, and it's eaten more memory than before. I'll paste the relevant parts. I'm not sure this is a
kernel thing, since I didn't have this problem before setting up a mirrored RAID array using mdadm.

from slabtop:
 Active / Total Objects (% used)    : 80755 / 86856 (93.0%)
 Active / Total Slabs (% used)      : 2974 / 2975 (100.0%)
 Active / Total Caches (% used)     : 76 / 140 (54.3%)
 Active / Total Size (% used)       : 11445.72K / 12330.93K (92.8%)
 Minimum / Average / Maximum Object : 0.01K / 0.14K / 128.00K

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME
 44469  44441  99%    0.05K    549       81      2196K buffer_head
  8946   8192  91%    0.27K    639       14      2556K radix_tree_node
  6960   4720  67%    0.13K    240       29       960K dentry_cache
  3510   3510 100%    0.09K     78       45       312K vm_area_struct
  3179   2522  79%    0.36K    289       11      1156K reiser_inode_cache
  3050   2477  81%    0.06K     50       61       200K size-64
  2782   2713  97%    0.04K     26      107       104K sysfs_dir_cache
  2405   2378  98%    0.29K    185       13       740K inode_cache
  2142   2142 100%    0.03K     18      119        72K size-32
  1860   1817  97%    0.12K     60       31       240K size-128
   875    875 100%    0.16K     35       25       140K filp

from free:
             total       used       free     shared    buffers     cached
Mem:        773900     765416       8484          0      75680     450004
- -/+ buffers/cache:     239732     534168
Swap:      2755136     118568    2636568


Something's digesting memory and not giving it back.
I'm now running 2.6.12.1 instead of 2.6.11.12 in the hopes that something was fixed, but no.

Thanks,
- --
David Kowis

ISO Team Lead - www.sourcemage.org
SourceMage GNU/Linux

One login to rule them all, one login to find them. One login to bring them all, and in the web bind them.
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