drm/i915: Add mmap lock around vma_lookup() in the mman selftest.
Add mmap_read_lock/unlock around vma_lookup(). The core code requires
this for lookups. Since we only check if the return value is NULL,
we can immediately unlock.
This fixes the following splat in the selftes:
i915: Running i915_gem_mman_live_selftests/igt_mmap
------------[ cut here ]------------
WARNING: CPU: 3 PID: 5654 at include/linux/mmap_lock.h:164 find_vma+0x4e/0xb0
Modules linked in: i915(+) vgem fuse snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio mei_hdcp x86_pkg_temp_thermal coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_intel_dspcfg snd_hda_codec snd_hwdep e1000e snd_hda_core ptp snd_pcm ttm mei_me pps_core i2c_i801 prime_numbers i2c_smbus mei [last unloaded: i915]
CPU: 3 PID: 5654 Comm: i915_selftest Tainted: G U 5.15.0-rc1-CI-Trybot_7984+ #1
Hardware name: Micro-Star International Co., Ltd. MS-7B54/Z370M MORTAR (MS-7B54), BIOS 1.00 10/31/2017
RIP: 0010:find_vma+0x4e/0xb0
Code: de 48 89 ef e8 d3 94 fe ff 48 85 c0 74 34 48 83 c4 08 5b 5d c3 48 8d bf 28 01 00 00 be ff ff ff ff e8 d6 46 8b 00 85 c0 75 c8 <0f> 0b 48 8b 85 b8 00 00 00 48 85 c0 75 c6 48 89 ef e8 12 26 87 00
RSP: 0018:
ffffc900013df980 EFLAGS:
00010246
RAX:
0000000000000000 RBX:
00007f9df2b80000 RCX:
0000000000000000
RDX:
0000000000000001 RSI:
ffffffff822e314c RDI:
ffffffff8233c83f
RBP:
ffff88811bafc840 R08:
ffff888107d0ddb8 R09:
00000000fffffffe
R10:
0000000000000001 R11:
00000000ffbae7ba R12:
0000000000000000
R13:
0000000000000000 R14:
ffff88812a710000 R15:
ffff888114fa42c0
FS:
00007f9def9d4c00(0000) GS:
ffff888266580000(0000) knlGS:
0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
CR2:
00007f799627fe50 CR3:
000000011bbc2006 CR4:
00000000003706e0
DR0:
0000000000000000 DR1:
0000000000000000 DR2:
0000000000000000
DR3:
0000000000000000 DR6:
00000000fffe0ff0 DR7:
0000000000000400
Call Trace:
__igt_mmap+0xe0/0x490 [i915]
igt_mmap+0xd2/0x160 [i915]
? __trace_bprintk+0x6e/0x80
__i915_subtests.cold.7+0x42/0x92 [i915]
? i915_perf_selftests+0x20/0x20 [i915]
? __i915_nop_setup+0x10/0x10 [i915]
__run_selftests.part.3+0x10d/0x172 [i915]
i915_live_selftests.cold.5+0x1f/0x47 [i915]
i915_pci_probe+0x93/0x1d0 [i915]
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/issues/4129
Link: https://patchwork.freedesktop.org/patch/msgid/20210915105946.394412-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Matthew Auld <matthew.auld@intel.com>