We run a debian 2.6.26-2-amd64 x86_64 GNU/Linux on a server with 128 Gb. Recently it our available memory became rather low. Looking at the /proc/meminfo showed that the Slab was using 88Gb, which is counted in the used memory off course.

1. Is this a problem? I suspect that memory will be freed when necessary, but I don't know if that could have unwanted side effects.
2. Why would Slab need that much memory? Is there a clear cause for that?
3. can we avoid this to happen in the future?
4. How can we free this memory?

thank you in advance

> cat /proc/meminfo
MemTotal:     132304500 kB
MemFree:      26669388 kB
Buffers:        237504 kB
Cached:       11881136 kB
SwapCached:         48 kB
Active:        5244640 kB
Inactive:     11714308 kB
SwapTotal:     5751228 kB
SwapFree:      5750436 kB
Dirty:              24 kB
Writeback:           0 kB
AnonPages:     4840256 kB
Mapped:         163968 kB
Slab:         88314840 kB
SReclaimable: 88275644 kB
SUnreclaim:      39196 kB
PageTables:      80852 kB
NFS_Unstable:        0 kB
Bounce:              0 kB
WritebackTmp:        0 kB
CommitLimit:  71903476 kB
Committed_AS:  6818332 kB
VmallocTotal: 34359738367 kB
VmallocUsed:    505724 kB
VmallocChunk: 34359231963 kB