[CentOS7] Page allocation failure on master node

[Dmitry Teselkin]

After successful master node deployment from CentOS7 based ISO there are error messages in /var/log/messages

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Dec 7 11:22:08 nailgun kernel: kworker/0:1: page allocation failure: order:0, mode:0x204000
Dec 7 11:22:08 nailgun kernel: CPU: 0 PID: 29 Comm: kworker/0:1 Not tainted 3.10.0-229.20.1.el7.x86_64 #1
Dec 7 11:22:08 nailgun kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Dec 7 11:22:08 nailgun kernel: Workqueue: kcopyd do_work [dm_mod]
Dec 7 11:22:08 nailgun kernel: 0000000000204000 000000001fe1b6eb ffff88003d4f34d8 ffffffff816045b6
Dec 7 11:22:08 nailgun kernel: ffff88003d4f3568 ffffffff8115c5c0 ffffea0000d8ee00 0000000000000000
Dec 7 11:22:08 nailgun kernel: ffff88003ffd9800 0000000000000000 ffff88003fc16978 000000001fe1b6eb
Dec 7 11:22:08 nailgun kernel: Call Trace:
Dec 7 11:22:08 nailgun kernel: [<ffffffff816045b6>] dump_stack+0x19/0x1b
Dec 7 11:22:08 nailgun kernel: [<ffffffff8115c5c0>] warn_alloc_failed+0x110/0x180
Dec 7 11:22:08 nailgun kernel: [<ffffffff81160d48>] __alloc_pages_nodemask+0x9a8/0xb90
Dec 7 11:22:08 nailgun kernel: [<ffffffff811ac81e>] ? __kmalloc+0x2e/0x230
Dec 7 11:22:08 nailgun kernel: [<ffffffffa008b41f>] ? __virtblk_add_req+0xdf/0x1c0 [virtio_blk]
Dec 7 11:22:08 nailgun kernel: [<ffffffff8119f3d9>] alloc_pages_current+0xa9/0x170
Dec 7 11:22:08 nailgun kernel: [<ffffffff811a94ac>] new_slab+0x2ec/0x300
Dec 7 11:22:08 nailgun kernel: [<ffffffff8160151b>] __slab_alloc+0x315/0x48f
Dec 7 11:22:08 nailgun kernel: [<ffffffffa012559c>] ? virtqueue_add_sgs+0x31c/0x59c [virtio_ring]
Dec 7 11:22:08 nailgun kernel: [<ffffffff812eda2d>] ? list_del+0xd/0x30
Dec 7 11:22:08 nailgun kernel: [<ffffffff816011eb>] ? get_partial_node.isra.48+0x1ee/0x209
Dec 7 11:22:08 nailgun kernel: [<ffffffff811ac9b8>] __kmalloc+0x1c8/0x230
Dec 7 11:22:08 nailgun kernel: [<ffffffffa012559c>] virtqueue_add_sgs+0x31c/0x59c [virtio_ring]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa008b41f>] __virtblk_add_req+0xdf/0x1c0 [virtio_blk]
Dec 7 11:22:08 nailgun kernel: [<ffffffff812b2fc6>] ? __blk_segment_map_sg+0x56/0x1b0
Dec 7 11:22:08 nailgun kernel: [<ffffffffa008b609>] virtio_queue_rq+0x109/0x280 [virtio_blk]
Dec 7 11:22:08 nailgun kernel: [<ffffffff812b6968>] __blk_mq_run_hw_queue+0x1c8/0x330
Dec 7 11:22:08 nailgun kernel: [<ffffffff812b70f5>] blk_mq_run_hw_queue+0x65/0x90
Dec 7 11:22:08 nailgun kernel: [<ffffffff812b80a8>] blk_sq_make_request+0x258/0x380
Dec 7 11:22:08 nailgun kernel: [<ffffffff812aa972>] generic_make_request+0xe2/0x130
Dec 7 11:22:08 nailgun kernel: [<ffffffff812aaa31>] submit_bio+0x71/0x150
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000ab7e>] dispatch_io+0x18e/0x360 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000a6b0>] ? dm_copy_name_and_uuid+0xc0/0xc0 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000a6e0>] ? list_get_page+0x30/0x30 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000b240>] ? dm_kcopyd_do_callback+0x40/0x40 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000ae5e>] dm_io+0x10e/0x2e0 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000a6b0>] ? dm_copy_name_and_uuid+0xc0/0xc0 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000a6e0>] ? list_get_page+0x30/0x30 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000bfa4>] run_io_job+0x124/0x200 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000b240>] ? dm_kcopyd_do_callback+0x40/0x40 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000b66d>] process_jobs+0x5d/0x100 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000be80>] ? dm_kcopyd_client_create+0x210/0x210 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffffa000b778>] do_work+0x68/0x90 [dm_mod]
Dec 7 11:22:08 nailgun kernel: [<ffffffff8108f0cb>] process_one_work+0x17b/0x470
Dec 7 11:22:08 nailgun kernel: [<ffffffff8108fe9b>] worker_thread+0x11b/0x400
Dec 7 11:22:08 nailgun kernel: [<ffffffff8108fd80>] ? rescuer_thread+0x400/0x400
Dec 7 11:22:08 nailgun kernel: [<ffffffff8109727f>] kthread+0xcf/0xe0
Dec 7 11:22:08 nailgun kernel: [<ffffffff810971b0>] ? kthread_create_on_node+0x140/0x140
Dec 7 11:22:08 nailgun kernel: [<ffffffff81614358>] ret_from_fork+0x58/0x90
Dec 7 11:22:08 nailgun kernel: [<ffffffff810971b0>] ? kthread_create_on_node+0x140/0x140
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[Ivan Suzdal (isuzdal)]

custom iso fuel-gerrit-8.0-1019-2015-12-07_14-02-04.iso include changes in boostrap_admin_node.sh which set min_free_kbytes to 65535

[Dmitry Teselkin (teselkin-d)]

According to [0] minimal hardware requirements for HW (production) master node are:
* Quad-core CPU
* 4GB RAM
* 1 gigabit network port
* 128GB SAS Disk
* IPMI access through independent management network

If there is 4 GB of ram the kernel sets vm.min_free_kbytes=67584 which is even more than in the patch provided. So we don't to do anything for production environment.

[0] https://docs.mirantis.com/openstack/fuel/fuel-7.0/planning-guide.html#system-requirements