sendto system call fails with error "No buffer space available", error code "ENOMEM". It seems to be failure of kmalloc within sendto. When I read about it, I learned that it could fail due nonavailability of contiguous memory. However, system has got enough free memory. I am not sure why kmalloc would fail. 

PS: I am running application in embedded hardware.

Error message when sendto failed:

```
MYAPP: page allocation failure. order:5, mode:0x4d0
[<c002b2a8>] (unwind_backtrace+0x0/0xcc) from [<c0063de0>] (__alloc_pages_internal+0x39c/0x3bc)

[<c0063de0>] (__alloc_pages_internal+0x39c/0x3bc) from [<c0294f40>] (cache_alloc_refill+0x264/0x514)

[<c0294f40>] (cache_alloc_refill+0x264/0x514) from [<c007a7e0>] (__kmalloc+0x84/0xd8)

[<c007a7e0>] (__kmalloc+0x84/0xd8) from [<c0213f88>] (__alloc_skb+0x44/0xf4)

[<c0213f88>] (__alloc_skb+0x44/0xf4) from [<c020fa2c>] (sock_alloc_send_pskb+0x94/0x2f8)

[<c020fa2c>] (sock_alloc_send_pskb+0x94/0x2f8) from [<c020fca8>] (sock_alloc_send_skb+0x18/0x1c)

[<c020fca8>] (sock_alloc_send_skb+0x18/0x1c) from [<c0273830>] (unix_dgram_sendmsg+0x168/0x44c)

[<c0273830>] (unix_dgram_sendmsg+0x168/0x44c) from [<c020d47c>] (sock_sendmsg+0xac/0xcc)

[<c020d47c>] (sock_sendmsg+0xac/0xcc) from [<c020e3fc>] (sys_sendto+0xb0/0xd4)

[<c020e3fc>] (sys_sendto+0xb0/0xd4) from [<c0025c00>] (ret_fast_syscall+0x0/0x2c)

Mem-info:

Normal per-cpu:

CPU    0: hi:   18, btch:   3 usd:   0

Active_anon:3321 active_file:194 inactive_anon:3324

inactive_file:2449 unevictable:173 dirty:0 writeback:0 unstable:0

free:4348 slab:929 mapped:1186 pagetables:115 bounce:0

Normal free:17392kB min:1016kB low:1268kB high:1524kB active_anon:13284kB inactive_anon:13296kB active_file:776kB inactive_file:9796kB unevictable:692kB present:65024kB pages_scanned:0 all_unreclaimable? no

lowmem_reserve[]: 0 0

Normal: 418*4kB 1251*8kB 347*16kB 3*32kB 1*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 17392kB

2876 total pagecache pages

16384 pages of RAM

4485 free pages

1097 reserved pages

929 slab pages

1401 pages shared

0 pages swap cached

```