As I read from http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/filesystems/proc.txt?id=HEAD#l451 (line 906)

the Shmem field in /proc/meminfo: Total memory used by shared memory (shmem) and tmpfs

tmpfs size:

/proc # df -Thk |grep -E "tmpfs|Used"
Filesystem               Type     1K-blocks    Used Available Use% Mounted on
devtmpfs                 devtmpfs   1963344       8   1963336   1% /dev
tmpfs                    tmpfs      2027904     728   2027176   1% /dev/shm
tmpfs                    tmpfs      2027904    9936   2017968   1% /run
tmpfs                    tmpfs      2027904       0   2027904   0% /sys/fs/cgroup

total (tmpfs) size: 8+ 728 + 9936 = 10672 kB

shared mem by ipc

/proc # ipcs -mu

------ Shared Memory Status --------
segments allocated 23
pages allocated 1855
pages resident  1855
pages swapped   0
Swap performance: 0 attempts     0 successes

/proc # getconf PAGESIZE
4096

-->ipcs shared mem = 1855 * 4096/1024 = 7420kB

> 7420kB (ipcs mem) + 10672 (tmpfs) = 18092 Kb

**

/proc # cat /proc/meminfo |grep Shmem
Shmem:  18096 kB  

which is different from Shmem in meminfo 4Kb could you help me about "where is 4Kb located?"

Thank you so much