linux - server running out of memory

itemprop="text">

src="https://i.stack.imgur.com/LylvG.jpg" alt="enter image description here">the
server is running out of memory and get to the point where it starts killing the
process, the total PSS memory(actual memory used from the Resident memory) consumed by
top using applications is less than the total memory on the system, i want to find out
where this extra memory usage is happening? any ideas, below are the output from
meminfo,smem,free -m,

any suggestions will be
really appreciated???

cat
            /proc/meminfo

MemTotal: 5976008 kB
MemFree: 138768
            kB

Buffers: 2292 kB
Cached: 57444
            kB
SwapCached: 85980 kB
Active: 324332 kB
Inactive: 121836
            kB
Active(anon): 309264 kB
Inactive(anon): 77992
            kB
Active(file): 15068 kB
Inactive(file): 43844
            kB
Unevictable: 0 kB

Mlocked: 0 kB
SwapTotal:
            8159224 kB
SwapFree: 6836184 kB
Dirty: 572 kB
Writeback: 0
            kB
AnonPages: 372160 kB
Mapped: 13976 kB
Shmem: 472
            kB
Slab: 328216 kB
SReclaimable: 92544
            kB

SUnreclaim: 235672 kB
KernelStack: 4824
            kB
PageTables: 14732 kB
NFS_Unstable: 0 kB
Bounce: 0
            kB
WritebackTmp: 0 kB
CommitLimit: 8159224
            kB
Committed_AS: 4940480 kB
VmallocTotal: 34359738367
            kB
VmallocUsed: 102424 kB

VmallocChunk: 34359584392
            kB
HardwareCorrupted: 0 kB
AnonHugePages: 0
            kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd:
            0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k:
            6384 kB
DirectMap2M: 2080768 kB

DirectMap1G: 4194304
            kB

SMEM usage:

30971 root python
            /usr/local/scripts/s 2432 660 860 1204
23296 root /usr/bin/spamd -d -c -m5 -H
            58296 1460 1564 1868
 2763 ufc csrv -c /home/ufc/ufclient/ 116000 12768 12792
            13084
55819 root /usr/bin/python /bin/smem 0 22356 22988 24364
 2101
            root clamd 189228 41224 41280 41700
32914 root /opt/safesquid/safesquid/sa
            831120 5808 138619 271844



[root@server
            sysadmin]# free -m
 total used free shared buffers cached
Mem: 5835
            5695 140 0 1 19
-/+ buffers/cache: 5674 161
Swap: 7967 1315
            6652

UPDATE:

The
server is back normal now, but the memory usage is exponential and it keeps going up
until after 7 hours the application gets
killed

Out of memory: Kill process
            14585 (safesquid) score 81 or sacrifice child
Killed process 16141, UID 500,
            (python) total-vm:79284kB, anon-rss:2656kB,
            file-rss:680kB



 top - 21:58:16 up 16 days,
            11:10, 1 user, load average: 0.46, 0.74,
 0.78 Tasks: 243 total, 1 running,
            242 sleeping, 0 stopped, 0 zombie Cpu(s): 5.7%us, 5.8%sy, 0.0%ni, 88.3%id, 0.1%wa,
            0.0%hi, 

 0.1%si, 0.0%st Mem: 5976008k total, 5830648k used,
            145360k free, 35724k buffers Swap: 8159224k total, 445384k used, 7713840k free, 3684540k
            cached


PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+
            COMMAND 
4960 ssquid 20 0 1000m 534m 3068 S 20.6 9.2 90:19.40 safesquid
            
2101 clamav 20 0 4153m 85m 1672 S 2.0 1.5 536:42.26 clamd 
23333
            root 20 0 244m 50m 1940 S 0.0 0.9 2:10.84 spamd 
2763 ufc 20 0 1628m 32m 25m S
            1.0 0.5 399:12.74 csrv 
61303 root 20 0 97876 4380 3304 S 0.0 0.1 0:00.28 sshd
            
23296 root 20 0 227m 3424 928 S 0.0 0.1 0:07.87
            spamd

the
box is running rulespace,clam and safesquid
proxy.

In the memory graph, the big drop is when
the application got killed, and i restarted the safesquid
service...

itemprop="text">

class="normal">Answer

@David
Schwartz: I am pretty sure the kernel OOM killer kills the process. And yes we need to
know which process is being killed.

I am pretty
sure the process that's being killed is misbehaving in some way (or crashing), as a
result it's using up most available memory at which point the kernel's OOM killer
decides to finish it off. For example, this kind of behaviour was rampant (in my case) a
decade or so ago when mozilla/firefox was more prone to leaking memory than it is now.
It'd just use more and more and suddenly it just disappeared... you get the
idea.