Update:
Moved that VE on another HN vith a new kernel, same distribution (CentOS 5.4 x86_64) with 24 GB of RAM
uname -a
Linux zzzzzz 2.6.18-164.2.1.el5.028stab066.10 #1 SMP Sat Dec 12 18:52:53 MSK 2009 x86_64 x86_64 x86_64 GNU/Linux
/proc/meminfo
MemTotal: 24624960 kB
MemFree: 288368 kB
Buffers: 1713548 kB
Cached: 20170624 kB
SwapCached: 0 kB
Active: 5424216 kB
Inactive: 17507444 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 24624960 kB
LowFree: 288368 kB
SwapTotal: 2097144 kB
SwapFree: 2096976 kB
Dirty: 1052500 kB
Writeback: 140 kB
AnonPages: 1048552 kB
Mapped: 174452 kB
Slab: 1310100 kB
PageTables: 27180 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 14409624 kB
Committed_AS: 7696144 kB
VmallocTotal: 34359738364 kB
VmallocUsed: 286208 kB
VmallocChunk: 34359451720 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 2048 kB
VE reports:
/proc/meminfo
MemTotal: 4613120 kB
MemTotal: 4613120 kB
MemFree: 2745300 kB
Buffers: 0 kB
Cached: 0 kB
SwapCached: 0 kB
Active: 0 kB
Inactive: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 4613120 kB
LowFree: 2745300 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 0 kB
Mapped: 0 kB
Slab: 0 kB
PageTables: 0 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 0 kB
Committed_AS: 0 kB
VmallocTotal: 0 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 2048 kB
/proc/user_beancounters
resource held maxheld barrier limit failcnt
kmemsize 32875448 47104131 95000000 95000000 0
lockedpages 0 7 256 256 0
privvmpages 540234 824747 1310720 1310720 0
shmpages 2576 2912 21504 21504 0
dummy 0 0 0 0 0
numproc 186 248 880 880 0
physpages 148452 256702 0 9223372036854775807 0
vmguarpages 0 0 524288 9223372036854775807 0
oomguarpages 148452 256702 26112 9223372036854775807 0
numtcpsock 149 278 1000 1000 0
numflock 6 30 188 206 0
numpty 1 1 16 16 0
numsiginfo 0 49 384 384 0
tcpsndbuf 1231840 3433336 8800000 11360000 0
tcprcvbuf 1245280 1990232 10000000 12560000 0
othersockbuf 148384 798960 2831155 3752755 0
dgramrcvbuf 0 133424 330000 330000 0
numothersock 87 122 360 360 0
dcachesize 2986196 3179234 6446000 11520000 0
numfile 6381 9414 30000 30000 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
dummy 0 0 0 0 0
numiptent 29 29 128 128 0
1310720 4K-pages equals exactly 5G (or 5242880 kB), instead of the 4613120 kB reported by /proc/meminfo.
Problem NOT solved...