Another stack trace from another instance:

20:34:16  [    2.425540] systemd-udevd[95]: starting version 204
20:34:16  [    2.576097] ------------[ cut here ]------------
20:34:16  [    2.576111] WARNING: CPU: 0 PID: 98 at /build/buildd/linux-3.16.0/mm/vmalloc.c:128 vmap_page_range_noflush+0x2d1/0x370()
20:34:16  [    2.576115] Modules linked in:
20:34:16  [    2.576120] CPU: 0 PID: 98 Comm: systemd-udevd Not tainted 3.16.0-6-generic #11-Ubuntu
20:34:16  [    2.576123]  0000000000000009 ffff88000316fb98 ffffffff81755538 0000000000000000
20:34:16  [    2.576128]  ffff88000316fbd0 ffffffff8106bb0d ffff88000400df68 0000000000000001
20:34:16  [    2.576132]  ffff880003393900 ffffffffc01ed000 0000000000000000 ffff88000316fbe0
20:34:16  [    2.576136] Call Trace:
20:34:16  [    2.576147]  [<ffffffff81755538>] dump_stack+0x45/0x56
20:34:16  [    2.576152]  [<ffffffff8106bb0d>] warn_slowpath_common+0x7d/0xa0
20:34:16  [    2.576156]  [<ffffffff8106bbea>] warn_slowpath_null+0x1a/0x20
20:34:16  [    2.576159]  [<ffffffff81197c31>] vmap_page_range_noflush+0x2d1/0x370
20:34:16  [    2.576163]  [<ffffffff81197cfe>] map_vm_area+0x2e/0x40
20:34:16  [    2.576167]  [<ffffffff8119a058>] __vmalloc_node_range+0x188/0x280
20:34:16  [    2.576175]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576178]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576183]  [<ffffffff8104f294>] module_alloc+0x74/0xd0
20:34:16  [    2.576187]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576190]  [<ffffffff810e92b4>] module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576194]  [<ffffffff810e9a6c>] layout_and_allocate+0x74c/0xc70
20:34:16  [    2.576198]  [<ffffffff810ea063>] load_module+0xd3/0x1b70
20:34:16  [    2.576202]  [<ffffffff811cfeb1>] ? vfs_read+0xf1/0x170
20:34:16  [    2.576206]  [<ffffffff810e7aa1>] ? copy_module_from_fd.isra.46+0x121/0x180
20:34:16  [    2.576209]  [<ffffffff810ebc76>] SyS_finit_module+0x86/0xb0
20:34:16  [    2.576217]  [<ffffffff8175de7f>] tracesys+0xe1/0xe6
20:34:16  [    2.576220] ---[ end trace 0f39a359bc0e983c ]---
20:34:16  [    2.576223] vmalloc: allocation failure, allocated 20480 of 24576 bytes
20:34:16  [    2.576226] systemd-udevd: page allocation failure: order:0, mode:0xd2
20:34:16  [    2.576229] CPU: 0 PID: 98 Comm: systemd-udevd Tainted: G        W     3.16.0-6-generic #11-Ubuntu
20:34:16  [    2.576232]  ffffffff81a88bc0 ffff88000316fc08 ffffffff81755538 00000000000000d2
20:34:16  [    2.576236]  ffff88000316fc90 ffffffff811642bf ffffffff81a88bc0 ffff88000316fc28
20:34:16  [    2.576239]  00003fff00000018 ffff88000316fca0 ffff88000316fc40 0000000000000163
20:34:16  [    2.576246] Call Trace:
20:34:16  [    2.576249]  [<ffffffff81755538>] dump_stack+0x45/0x56
20:34:16  [    2.576254]  [<ffffffff811642bf>] warn_alloc_failed+0xdf/0x130
20:34:16  [    2.576257]  [<ffffffff8119a118>] __vmalloc_node_range+0x248/0x280
20:34:16  [    2.576261]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576264]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576267]  [<ffffffff8104f294>] module_alloc+0x74/0xd0
20:34:16  [    2.576271]  [<ffffffff810e92b4>] ? module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576274]  [<ffffffff810e92b4>] module_alloc_update_bounds+0x14/0x70
20:34:16  [    2.576278]  [<ffffffff810e9a6c>] layout_and_allocate+0x74c/0xc70
20:34:16  [    2.576281]  [<ffffffff810ea063>] load_module+0xd3/0x1b70
20:34:16  [    2.576287]  [<ffffffff811cfeb1>] ? vfs_read+0xf1/0x170
20:34:16  [    2.576290]  [<ffffffff810e7aa1>] ? copy_module_from_fd.isra.46+0x121/0x180
20:34:16  [    2.576294]  [<ffffffff810ebc76>] SyS_finit_module+0x86/0xb0
20:34:16  [    2.576298]  [<ffffffff8175de7f>] tracesys+0xe1/0xe6
20:34:16  [    2.576300] Mem-Info:
20:34:16  [    2.576302] Node 0 DMA per-cpu:
20:34:16  [    2.576304] CPU    0: hi:    0, btch:   1 usd:   0
20:34:16  [    2.576306] Node 0 DMA32 per-cpu:
20:34:16  [    2.576311] CPU    0: hi:  186, btch:  31 usd: 125
20:34:16  [    2.576315] active_anon:630 inactive_anon:13 isolated_anon:0
20:34:16  [    2.576315]  active_file:975 inactive_file:4521 isolated_file:0
20:34:16  [    2.576315]  unevictable:0 dirty:0 writeback:0 unstable:0
20:34:16  [    2.576315]  free:943953 slab_reclaimable:1610 slab_unreclaimable:1090
20:34:16  [    2.576315]  mapped:836 shmem:19 pagetables:285 bounce:0
20:34:16  [    2.576315]  free_cma:16384
20:34:16  [    2.576325] Node 0 DMA free:15852kB min:32kB low:40kB high:48kB active_anon:24kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15996kB managed:15912kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:12kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
20:34:16  [    2.576338] lowmem_reserve[]: 0 3730 3730 3730
20:34:16  [    2.576342] Node 0 DMA32 free:3759960kB min:7796kB low:9744kB high:11692kB active_anon:2496kB inactive_anon:52kB active_file:3900kB inactive_file:18084kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:3923968kB managed:3822724kB mlocked:0kB dirty:0kB writeback:0kB mapped:3344kB shmem:76kB slab_reclaimable:6440kB slab_unreclaimable:4348kB kernel_stack:768kB pagetables:1140kB unstable:0kB bounce:0kB free_cma:65536kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
20:34:16  [    2.576358] lowmem_reserve[]: 0 0 0 0
20:34:16  [    2.576362] Node 0 DMA: 1*4kB (E) 3*8kB (UEM) 1*16kB (E) 2*32kB (EM) 4*64kB (UEM) 3*128kB (UEM) 3*256kB (UEM) 2*512kB (EM) 3*1024kB (UEM) 3*2048kB (EMR) 1*4096kB (M) = 15852kB
20:34:16  [    2.576379] Node 0 DMA32: 6*4kB (UM) 4*8kB (U) 7*16kB (UEM) 3*32kB (UEM) 1*64kB (U) 2*128kB (UE) 3*256kB (UM) 5*512kB (EM) 4*1024kB (UEM) 2*2048kB (UM) 915*4096kB (MRC) = 3759944kB
20:34:16  [    2.576394] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
20:34:16  [    2.576397] 5502 total pagecache pages
20:34:16  [    2.576399] 0 pages in swap cache
20:34:16  [    2.576401] Swap cache stats: add 0, delete 0, find 0/0
20:34:16  [    2.576403] Free swap  = 0kB
20:34:16  [    2.576405] Total swap = 0kB
20:34:16  [    2.576407] 984991 pages RAM
20:34:16  [    2.576411] 0 pages HighMem/MovableOnly
20:34:16  [    2.576413] 25311 pages reserved
20:34:16  [    2.576414] 0 pages hwpoisoned
20:34:16  Begin: Loading essential drivers ... done.