Comment 5 for bug 1809879

Kernel trace triggered by this test:
[ 385.822256] ------------[ cut here ]------------
[ 385.822262] WARNING: CPU: 1 PID: 1487 at /build/linux-pWDSBu/linux-3.13.0/mm/page_alloc.c:2552 __alloc_pages_nodemask+0x455/0xb90()
[ 385.822263] Modules linked in: ib_iser rdma_cm iw_cm ib_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi dm_crypt x86_pkg_temp_thermal coretemp kvm_intel kvm joydev lpc_ich shpchp mac_hid btrfs xor raid6_pq libcrc32c crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel igb aes_x86_64 hid_generic lrw i915_bdw dca gf128mul intel_ips glue_helper usbhid ptp ablk_helper drm_kms_helper cryptd ahci hid drm pps_core libahci i2c_algo_bit video
[ 385.822286] CPU: 1 PID: 1487 Comm: btrfs Not tainted 3.13.0-164-generic #214-Ubuntu
[ 385.822287] Hardware name: Intel Corporation S1200RP/S1200RP, BIOS S1200RP.86B.03.02.0003.070120151022 07/01/2015
[ 385.822288] 0000000000000000 ffff8804551916d8 ffffffff8173c0c8 0000000000000000
[ 385.822290] 0000000000000009 ffff880455191710 ffffffff8106db6d 0000000000124050
[ 385.822292] 0000000000000000 0000000000104050 0000000000000000 0000000000000000
[ 385.822294] Call Trace:
[ 385.822298] [<ffffffff8173c0c8>] dump_stack+0x64/0x80
[ 385.822301] [<ffffffff8106db6d>] warn_slowpath_common+0x7d/0xa0
[ 385.822303] [<ffffffff8106dc4a>] warn_slowpath_null+0x1a/0x20
[ 385.822305] [<ffffffff81161bd5>] __alloc_pages_nodemask+0x455/0xb90
[ 385.822317] [<ffffffffa02dfa4d>] ? generic_bin_search.constprop.35+0x8d/0x1a0 [btrfs]
[ 385.822320] [<ffffffff811a1e53>] alloc_pages_current+0xa3/0x160
[ 385.822323] [<ffffffff8115c92e>] __get_free_pages+0xe/0x50
[ 385.822325] [<ffffffff81179abe>] kmalloc_order_trace+0x2e/0xc0
[ 385.822327] [<ffffffff811afc3f>] __kmalloc_track_caller+0x23f/0x260
[ 385.822336] [<ffffffffa0363e67>] ? fs_path_ensure_buf+0x67/0x1c0 [btrfs]
[ 385.822338] [<ffffffff81173d7f>] krealloc+0x4f/0xa0
[ 385.822345] [<ffffffffa0363e67>] fs_path_ensure_buf+0x67/0x1c0 [btrfs]
[ 385.822352] [<ffffffffa0363ff3>] fs_path_prepare_for_add+0x33/0xa0 [btrfs]
[ 385.822359] [<ffffffffa0364ae0>] fs_path_add_path+0x20/0x50 [btrfs]
[ 385.822365] [<ffffffffa0364fdb>] get_cur_path+0x6b/0x140 [btrfs]
[ 385.822371] [<ffffffffa0365340>] send_utimes+0xd0/0x190 [btrfs]
[ 385.822378] [<ffffffffa03662ce>] finish_inode_if_needed+0x1fe/0x4e0 [btrfs]
[ 385.822384] [<ffffffffa0367e35>] changed_cb+0x55/0x9f0 [btrfs]
[ 385.822392] [<ffffffffa0324e5c>] ? read_extent_buffer+0xbc/0x110 [btrfs]
[ 385.822399] [<ffffffffa0319d89>] ? btrfs_get_token_32+0x59/0xe0 [btrfs]
[ 385.822406] [<ffffffffa03255f1>] ? memcmp_extent_buffer+0xc1/0x120 [btrfs]
[ 385.822411] [<ffffffffa02e4fb3>] btrfs_compare_trees+0x783/0x960 [btrfs]
[ 385.822418] [<ffffffffa0367de0>] ? process_extent+0x1180/0x1180 [btrfs]
[ 385.822424] [<ffffffffa0369078>] btrfs_ioctl_send+0x8a8/0xc90 [btrfs]
[ 385.822432] [<ffffffffa0337579>] btrfs_ioctl+0x1129/0x2770 [btrfs]
[ 385.822434] [<ffffffff810ad752>] ? enqueue_task_fair+0x422/0x6d0
[ 385.822436] [<ffffffff810a4cc5>] ? sched_clock_cpu+0xb5/0x100
[ 385.822439] [<ffffffff8109b8d0>] ? enqueue_task+0x40/0x70
[ 385.822441] [<ffffffff810a1ba0>] ? wake_up_new_task+0x110/0x1a0
[ 385.822444] [<ffffffff811dc653>] do_vfs_ioctl+0x2e3/0x4d0
[ 385.822446] [<ffffffff811dc8c1>] SyS_ioctl+0x81/0xa0
[ 385.822448] [<ffffffff8174d37c>] system_call_fastpath+0x26/0x2b
[ 385.822449] ---[ end trace 5634bd9ec366973a ]---