This should hit the BUG inside remap_pfn_range in

commit c5158fabeaf53ed2c614c3333aaa4b3cce80f500
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Tue Jun 10 12:14:41 2014 +0100

[   27.767634] kernel BUG at mm/memory.c:2315!
[   27.767655] invalid opcode: 0000 [#1

] SMP
[   27.767679] Modules linked in: cpufreq_userspace cpufreq_powersave cpufreq_stats cpufreq_conservative binfmt_misc nfs lockd fscache sunrpc hid_generic usbhid hid x86_pkg_temp_thermal microcode i2c_i801 lpc_ich mfd_core battery acpi_cpufreq evdev processor ac loop ehci_pci xhci_hcd ehci_hcd sr_mod usbcore cdrom usb_common fan thermal
[   27.767872] CPU: 3 PID: 912 Comm: gem_mmap_gtt Not tainted 3.15.0-rc8+ #953
[   27.767903] Hardware name: Intel Corporation Shark Bay Client platform/Flathead Creek Crb, BIOS HSWLPTU1.86C.0109.R03.1301282055 01/28/2013
[   27.767956] task: ffff880448415010 ti: ffff88044d22c000 task.ti: ffff88044d22c000
[   27.767988] RIP: 0010:[<ffffffff81130734>]  [<ffffffff81130734>] remap_pfn_range+0x2a4/0x400
[   27.768033] RSP: 0000:ffff88044d22fc28  EFLAGS: 00010282
[   27.768057] RAX: 0000000000020002 RBX: 00000000000a3b57 RCX: ffff880448b73fe8
[   27.768088] RDX: 0000000000000002 RSI: ffff880000000000 RDI: ffffea000efe8158
[   27.768119] RBP: ffff88044d22fcd8 R08: 00007fc7b57fe000 R09: 00007fc7b57fe000
[   27.768150] R10: 00000000000001fd R11: 0000000000000a9a R12: ffffea000efe8128
[   27.768180] R13: 0000000000000001 R14: 00007fc7b57fd000 R15: 800000000000002f
[   27.768212] FS:  00007fc7977fc700(0000) GS:ffff88045e380000(0000) knlGS:0000000000000000
[   27.768246] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   27.768272] CR2: 00007fc7b67fd000 CR3: 000000044866c000 CR4: 00000000001407e0
[   27.768303] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   27.768333] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   27.768363] Stack:
[   27.768374]  ffff880448bbb6f8 00000000ffffffff 00007fc7b57fdfff 00007fc7b57fdfff
[   27.768414]  00007fc7b57fe000 ffff88044866c7f8 ffff8804496b08f0 00007fc7b57fdfff
[   27.768454]  fffffff8038ee35a 0000000000001000 ffff88044c208180 00007fc7b57fe000
[   27.768494] Call Trace:
[   27.768511]  [<ffffffff81365277>] i915_gem_fault+0x337/0x340
[   27.768538]  [<ffffffff8112d3c4>] __do_fault+0x34/0x70
[   27.768565]  [<ffffffff8109088e>] ? wake_up_process+0x1e/0x40
[   27.768592]  [<ffffffff8113015c>] do_shared_fault.isra.96+0x2c/0x1f0
[   27.768623]  [<ffffffff81502405>] ? rwsem_down_read_failed+0xe5/0x130
[   27.768654]  [<ffffffff810a2519>] ? __rwsem_do_wake+0x129/0x160
[   27.768682]  [<ffffffff81131085>] handle_mm_fault+0x2b5/0xb80
[   27.768712]  [<ffffffff81270a64>] ? call_rwsem_down_read_failed+0x14/0x30
[   27.768745]  [<ffffffff81036c67>] __do_page_fault+0x167/0x4c0
[   27.768774]  [<ffffffff8109a540>] ? pick_next_task_fair+0x700/0x870
[   27.768804]  [<ffffffff814ff23b>] ? __schedule+0x27b/0x860
[   27.768831]  [<ffffffff81036fec>] do_page_fault+0xc/0x10
[   27.768857]  [<ffffffff815034a2>] page_fault+0x22/0x30
[   27.768881] Code: 4d 85 ed 49 0f 44 d7 80 cc 02 49 81 c6 00 10 00 00 48 83 c3 01 48 83 c1 08 48 09 d0 48 89 41 f8 4d 39 f0 74 32 48 83 39 00 74 c4 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 48 39 37 75 63 48 8b 45 c8
[   27.769081] RIP  [<ffffffff81130734>] remap_pfn_range+0x2a4/0x400
[   27.769113]  RSP <ffff88044d22fc28>

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>