BUG w kernelu CentOS 7.4

Kilka dni temu wyszedł CentOS 7.4. Długo na niego czekałem, więc czym prędzej zaaktualizowałem jedną z maszyn wirtualnych opartych na Xen-ie. Trochę się zdziwiłem, bo po restarcie serwer nie wstał, a na konsoli zobaczyłem niepokojące komunikaty”:

[ 1.970708] Call Trace:
[ 1.970725] [<ffffffff816a3d91>] dump_stack+0x19/0x1b
[ 1.970736] [<ffffffff810879c8>] __warn+0xd8/0x100
[ 1.970742] [<ffffffff81087b0d>] warn_slowpath_null+0x1d/0x20
[ 1.970748] [<ffffffff811c0781>] vmap_page_range_noflush+0x2c1/0x350
[ 1.970758] [<ffffffff811c083e>] map_vm_area+0x2e/0x40
[ 1.970765] [<ffffffff811c1590>] __vmalloc_node_range+0x170/0x270
[ 1.970774] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.970781] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.970792] [<ffffffff8105f143>] module_alloc+0x73/0xd0
[ 1.970798] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.970804] [<ffffffff810fe754>] module_alloc_update_bounds+0x14/0x70
[ 1.970811] [<ffffffff810ff2d2>] load_module+0xb02/0x29e0
[ 1.970817] [<ffffffff811c0717>] ? vmap_page_range_noflush+0x257/0x350
[ 1.970823] [<ffffffff811c083e>] ? map_vm_area+0x2e/0x40
[ 1.970829] [<ffffffff811c1590>] ? __vmalloc_node_range+0x170/0x270
[ 1.970838] [<ffffffff81101249>] ? SyS_init_module+0x99/0x110
[ 1.970846] [<ffffffff81101275>] SyS_init_module+0xc5/0x110
[ 1.970856] [<ffffffff816b4fc9>] system_call_fastpath+0x16/0x1b
[ 1.970862] ---[ end trace 2117480876ed90d2 ]---
[ 1.970869] vmalloc: allocation failure, allocated 24576 of 28672 bytes
[ 1.970874] systemd-udevd: page allocation failure: order:0, mode:0xd2
[ 1.970883] CPU: 2 PID: 225 Comm: systemd-udevd Tainted: G W
------------ 3.10.0-693.2.2.el7.x86_64 #1
[ 1.970894] 00000000000000d2 000000008cddc75d ffff8803e8587c48
ffffffff816a3d91
[ 1.970910] ffff8803e8587cd8 ffffffff81188810 ffffffff8190ea38
ffff8803e8587c68
[ 1.970923] ffffffff00000018 ffff8803e8587ce8 ffff8803e8587c88
000000008cddc75d
[ 1.970939] Call Trace:
[ 1.970946] [<ffffffff816a3d91>] dump_stack+0x19/0x1b
[ 1.970961] [<ffffffff81188810>] warn_alloc_failed+0x110/0x180
[ 1.970971] [<ffffffff811c1654>] __vmalloc_node_range+0x234/0x270
[ 1.970981] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.970989] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.970999] [<ffffffff8105f143>] module_alloc+0x73/0xd0
[ 1.971031] [<ffffffff810fe754>] ? module_alloc_update_bounds+0x14/0x70
[ 1.971038] [<ffffffff810fe754>] module_alloc_update_bounds+0x14/0x70
[ 1.971046] [<ffffffff810ff2d2>] load_module+0xb02/0x29e0
[ 1.971052] [<ffffffff811c0717>] ? vmap_page_range_noflush+0x257/0x350
[ 1.971061] [<ffffffff811c083e>] ? map_vm_area+0x2e/0x40
[ 1.971067] [<ffffffff811c1590>] ? __vmalloc_node_range+0x170/0x270
[ 1.971075] [<ffffffff81101249>] ? SyS_init_module+0x99/0x110
[ 1.971081] [<ffffffff81101275>] SyS_init_module+0xc5/0x110
[ 1.971088] [<ffffffff816b4fc9>] system_call_fastpath+0x16/0x1b
[ 1.971094] Mem-Info:
[ 1.971103] active_anon:875 inactive_anon:2049 isolated_anon:0
[ 1.971103] active_file:791 inactive_file:8841 isolated_file:0
[ 1.971103] unevictable:0 dirty:0 writeback:0 unstable:0
[ 1.971103] slab_reclaimable:1732 slab_unreclaimable:1629
[ 1.971103] mapped:1464 shmem:2053 pagetables:480 bounce:0
[ 1.971103] free:4065966 free_pcp:763 free_cma:0
[ 1.971131] Node 0 DMA free:15912kB min:12kB low:12kB high:16kB
active_anon:0kB 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:0kB kernel_stack:0kB
pagetables:0kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB
free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
[ 1.971217] lowmem_reserve[]: 0 4063 16028 16028
[ 1.971226] Node 0 DMA32 free:4156584kB min:4104kB low:5128kB
high:6156kB active_anon:952kB inactive_anon:1924kB active_file:0kB
inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB
present:4177920kB managed:4162956kB mlocked:0kB dirty:0kB writeback:0kB
mapped:4kB shmem:1928kB slab_reclaimable:240kB slab_unreclaimable:504kB
kernel_stack:32kB pagetables:592kB unstable:0kB bounce:0kB
free_pcp:1760kB local_pcp:288kB free_cma:0kB writeback_tmp:0kB
pages_scanned:0 all_unreclaimable? no
[ 1.971264] lowmem_reserve[]: 0 0 11964 11964
[ 1.971273] Node 0 Normal free:12091564kB min:12088kB low:15108kB
high:18132kB active_anon:2352kB inactive_anon:6272kB active_file:3164kB
inactive_file:35364kB unevictable:0kB isolated(anon):0kB
isolated(file):0kB present:12591104kB managed:12251788kB mlocked:0kB
dirty:0kB writeback:0kB mapped:5852kB shmem:6284kB
slab_reclaimable:6688kB slab_unreclaimable:6012kB kernel_stack:880kB
pagetables:1328kB unstable:0kB bounce:0kB free_pcp:1196kB
local_pcp:152kB free_cma:0kB writeback_tmp:0kB pages_scanned:0
all_unreclaimable? no
[ 1.971309] lowmem_reserve[]: 0 0 0 0
[ 1.971316] Node 0 DMA: 0*4kB 1*8kB (U) 0*16kB 1*32kB (U) 2*64kB (U)
1*128kB (U) 1*256kB (U) 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) =
15912kB
[ 1.971343] Node 0 DMA32: 7*4kB (M) 18*8kB (UM) 7*16kB (EM) 3*32kB
(EM) 1*64kB (E) 2*128kB (UM) 1*256kB (E) 4*512kB (UM) 4*1024kB (UEM)
4*2048kB (EM) 1011*4096kB (M) = 4156348kB
[ 1.971377] Node 0 Normal: 64*4kB (UEM) 10*8kB (UEM) 6*16kB (EM)
3*32kB (EM) 3*64kB (UE) 3*128kB (UEM) 1*256kB (E) 2*512kB (UE) 0*1024kB
1*2048kB (M) 2951*4096kB (M) = 12091728kB
[ 1.971413] Node 0 hugepages_total=0 hugepages_free=0
hugepages_surp=0 hugepages_size=2048kB
[ 1.971425] 11685 total pagecache pages
[ 1.971430] 0 pages in swap cache
[ 1.971437] Swap cache stats: add 0, delete 0, find 0/0
[ 1.971444] Free swap = 0kB
[ 1.971451] Total swap = 0kB
[ 1.971456] 4196255 pages RAM
[ 1.971462] 0 pages HighMem/MovableOnly
[ 1.971467] 88591 pages reserved
Problem dotyczy kerneli z serii 3.10.0-693.*.el7.x86_64 i maszyn klienckich korzystających z wirtualizacji Xen. Najprostszym wyjściem jest edycji pliku „/boot/grub/menu.lst” i zmiana opcji „default” z 0 na 1. Aby jednak w ogóle odpalić maszynę, trzeba w oknie wyboru kernela, ustawić jeden z poprzednich.