[Intel-gfx] [PATCH] drm/i915/selftests: Disable shrinker across mmap-exhaustion

[Chris Wilson]

Quoting Mika Kuoppala (2018-10-11 14:56:42)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > For mmap-exhaustion, we deliberately put the system under a large amount
> > of pressure to ensure that we are able to reap mmap-offsets from dead
> > objects. If background activity does that reaping for us, that defeats
> > the purpose of the test and in some cases will fail our sanity checks
> > (because of the fake activity we use to prevent the idle worker).
> >
> 
> mark_obj_busy will both pin and mark the object as active. And we
> have disabled the retire worker. So how can an active object
> end up being purged?

The shrinker.

<3> [390.421056] i915_gem_wait_for_idle:3426 GEM_BUG_ON(i915->gt.active_requests)
<4> [390.421904] ------------[ cut here ]------------
<2> [390.421907] kernel BUG at drivers/gpu/drm/i915/i915_gem.c:3426!
<4> [390.421921] invalid opcode: 0000 [#1] PREEMPT SMP PTI
<4> [390.421927] CPU: 1 PID: 51 Comm: kswapd0 Tainted: G     U            4.19.0-rc7-CI-Trybot_3063+ #1
<4> [390.421930] Hardware name: Intel Corp. Geminilake/GLK RVP2 LP4SD (07), BIOS GELKRVPA.X64.0062.B30.1708222146 08/22/2017
<4> [390.422030] RIP: 0010:i915_gem_wait_for_idle.part.25+0x205/0x210 [i915]
<4> [390.422034] Code: 3a 3b 6d e0 48 8b 35 aa b8 1d 00 49 c7 c0 0a 9a b4 a0 b9 62 0d 00 00 48 c7 c2 90 fc b2 a0 48 c7 c7 00 65 a2 a0 e8 8b ca 73 e0 <0f> 0b 66 0f 1f 84 00 00 00 00 00 49 89 fa 31 c0 48 89 f7 b9 14 00
<4> [390.422037] RSP: 0018:ffffc900003a7b78 EFLAGS: 00010286
<4> [390.422041] RAX: 000000000000000e RBX: 000000000000000a RCX: 0000000000000000
<4> [390.422043] RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff88017b1efa38
<4> [390.422046] RBP: ffff88006c53b1d0 R08: 00000000001b1b25 R09: ffff88017b344000
<4> [390.422048] R10: 0000000000000000 R11: ffff88017b1efa38 R12: 0000005ac6b50a70
<4> [390.422051] R13: ffff88006c530000 R14: ffff88006c53b270 R15: 0000000000000002
<4> [390.422054] FS:  0000000000000000(0000) GS:ffff88017ba80000(0000) knlGS:0000000000000000
<4> [390.422057] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
<4> [390.422059] CR2: 00007f5016f07228 CR3: 0000000005210000 CR4: 0000000000340ee0
<4> [390.422061] Call Trace:
<4> [390.422124]  i915_gem_shrink+0x486/0x5b0 [i915]
<4> [390.422136]  ? shrink_node+0xe2/0x450
<4> [390.422197]  ? i915_gem_shrinker_scan+0x10e/0x130 [i915]
<4> [390.422256]  i915_gem_shrinker_scan+0x10e/0x130 [i915]
<4> [390.422263]  do_shrink_slab+0x13e/0x3d0
<4> [390.422269]  shrink_slab+0x228/0x2c0
<4> [390.422275]  shrink_node+0xe2/0x450
<4> [390.422281]  kswapd+0x2f8/0x8f0
<4> [390.422289]  ? mem_cgroup_shrink_node+0x290/0x290
<4> [390.422294]  kthread+0x119/0x130
<4> [390.422298]  ? kthread_park+0x80/0x80
<4> [390.422305]  ret_from_fork+0x3a/0x50
-Chris