The vma->exec_list is still the only means we have for both reserving an
object in execbuf, and for constructing the eviction list. So during the
construction of the eviction list, we must treat anything already on the
exec_list as being pinned.

Yes, this sharing of two semantically different lists will be fixed! But
in the meantime, we have the issue that this is tripping up CI since we
started using i915_gem_gtt_reserve_node() + i915_gem_evict_for_node()
from the regular execbuf reservation path in commit 606fec95
("drm/i915: Prefer random replacement before eviction search"):

[  108.424063] kernel BUG at drivers/gpu/drm/i915/i915_vma.h:254!
[  108.424072] invalid opcode: 0000 [#1] PREEMPT SMP
[  108.424079] Modules linked in: snd_hda_intel i915 intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core mei_me snd_pcm lpc_ich mei sdhci_pci sdhci mmc_core e1000e ptp pps_core [last unloaded: i915]
[  108.424132] CPU: 1 PID: 6865 Comm: gem_cs_tlb Tainted: G     U          4.10.0-rc3-CI-CI_DRM_2049+ #1
[  108.424143] Hardware name: Hewlett-Packard HP EliteBook 8440p/172A, BIOS 68CCU Ver. F.24 09/13/2013
[  108.424154] task: ffff88012ae22600 task.stack: ffffc90000a14000
[  108.424220] RIP: 0010:i915_gem_evict_for_node+0x237/0x410 [i915]
[  108.424229] RSP: 0018:ffffc90000a17a58 EFLAGS: 00010202
[  108.424237] RAX: 0000000000005871 RBX: ffff88012d1ad778 RCX: 0000000000000000
[  108.424246] RDX: 000000007ffff000 RSI: ffffc90000a17a68 RDI: ffff880127e694d8
[  108.424255] RBP: ffffc90000a17aa0 R08: ffffc90000a17a68 R09: 0000000000000000
[  108.424264] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000080000000
[  108.424273] R13: ffffc90000a17a68 R14: ffff880127e694d8 R15: ffffffffa0387330
[  108.424283] FS:  00007f8236e3d8c0(0000) GS:ffff880137c40000(0000) knlGS:0000000000000000
[  108.424293] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  108.424305] CR2: 00007f82347a2000 CR3: 000000012c866000 CR4: 00000000000006e0
[  108.424317] Call Trace:
[  108.424368]  i915_gem_gtt_reserve+0x67/0x80 [i915]
[  108.424424]  __i915_vma_do_pin+0x248/0x620 [i915]
[  108.424487]  ? __i915_vma_do_pin+0x162/0x620 [i915]
[  108.424540]  i915_gem_execbuffer_reserve_vma.isra.8+0x153/0x1f0 [i915]
[  108.424591]  i915_gem_execbuffer_reserve.isra.9+0x40e/0x440 [i915]
[  108.424643]  i915_gem_do_execbuffer.isra.15+0x6d9/0x1b20 [i915]
[  108.424696]  i915_gem_execbuffer2+0xc0/0x250 [i915]
[  108.424712]  drm_ioctl+0x200/0x450
[  108.424760]  ? i915_gem_execbuffer+0x330/0x330 [i915]
[  108.424776]  do_vfs_ioctl+0x90/0x6e0
[  108.424789]  ? up_read+0x1a/0x40
[  108.424800]  ? trace_hardirqs_on_caller+0x122/0x1b0
[  108.424813]  SyS_ioctl+0x3c/0x70
[  108.424828]  entry_SYSCALL_64_fastpath+0x1c/0xb1
[  108.424839] RIP: 0033:0x7f8235867357
[  108.424848] RSP: 002b:00007ffdc14504c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[  108.424866] RAX: ffffffffffffffda RBX: 00007ffdc1450600 RCX: 00007f8235867357
[  108.424878] RDX: 00007ffdc14505a0 RSI: 0000000040406469 RDI: 0000000000000003
[  108.424890] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000022
[  108.424903] R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000002
[  108.424915] R13: 0000000000419101 R14: 00007ffdc1450600 R15: 00007ffdc14505f0
[  108.424928] Code: 45 b8 8b 4d c0 4c 89 f2 48 89 de ff d0 49 8b 07 4c 8b 45 b8 48 85 c0 75 dd 65 ff 0d d4 a1 c8 5f 0f 84 47 01 00 00 e9 0d fe ff ff <0f> 0b 45 31 f6 4c 8b 65 c8 49 8b 04 24 4d 39 ec 49 8d 9c 24 28
[  108.425055] RIP: i915_gem_evict_for_node+0x237/0x410 [i915] RSP: ffffc90000a17a58

Fixes: 172ae5b4 ("drm/i915: Fix i915_gem_evict_for_vma (soft-pinning)")
Fixes: 606fec95 ("drm/i915: Prefer random replacement before eviction search")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111182132.19174-1-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>