Red Hat Bugzilla – Bug 159184
excessive ext3_inode_cache slab usage
Last modified: 2015-01-04 17:19:58 EST
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Description of problem:
An excessive amount of memory is being allocated to the slab for the ext3_inode_cache. On a machine with 8GB ram and no applications running, free reports 4.5GB of ram in use:
total used free shared buffers cached
Mem: 8079404 6034904 2044500 0 853652 649828
-/+ buffers/cache: 4531424 3547980
Swap: 2096472 0 2096472
The interesting part is from slabtop, though:
Active / Total Objects (% used) : 7502225 / 7509918 (99.9%)
Active / Total Slabs (% used) : 1120402 / 1120404 (100.0%)
Active / Total Caches (% used) : 93 / 131 (71.0%)
Active / Total Size (% used) : -305009.98K / -304212.66K (100.3%)
Minimum / Average / Maximum Object : 0.02K / -0.04K / 128.00K
OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
3554924 3554923 99% 0.84K 888731 4 3554924K ext3_inode_cache
3585946 3585941 99% 0.23K 210938 17 843752K dentry_cache
Note that it shows 3.5G of ram being used for the ext3_inode_cache.
I believe the memory got used when backups ran (a process that would walk the filesystem tree). But it hasn't gone down since then (24 hours). This might be related to Bug 150945, but there people were complaining about a couple hundred meg of slab usage, whereas here it's 3.5G.
Marking as "high" severity since 3.5G memory disappearing constitutes a "severe memory leak" IMHO.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. run a process that walks a large directory tree like du or updatedb
Does this memory get reclaimed if you run something that needs lots of memory ?
This could be perfectly normal, unless it doesn't get reclaimed.
An update has been released for Fedora Core 3 (kernel-2.6.12-1.1372_FC3) which
may contain a fix for your problem. Please update to this new kernel, and
report whether or not it fixes your problem.
If you have updated to Fedora Core 4 since this bug was opened, and the problem
still occurs with the latest updates for that release, please change the version
field of this bug to 'fc4'.