[Intel-gfx] [PATCH] drm/i915: More vma fixups around unbind/destroy
Daniel Vetter
daniel at ffwll.ch
Mon Aug 26 11:27:05 CEST 2013
On Mon, Aug 26, 2013 at 11:23:47AM +0200, Daniel Vetter wrote:
> The important bugfix here is that we must not unlink the vma when
> we keep it around as a placeholder for the execbuf code. Since then we
> won't find it again when execbuf gets interrupt and restarted and
> create a 2nd vma. And since the code as-is isn't fit yet to deal with
> more than one vma, hilarity ensues.
>
> Specifically the dma map/unmap of the sg table isn't adjusted for
> multiple vmas yet and will blow up like this:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> IP: [<ffffffffa008fb37>] i915_gem_gtt_finish_object+0x73/0xc8 [i915]
> PGD 56bb5067 PUD ad3dd067 PMD 0
> Oops: 0000 [#1] SMP
> Modules linked in: tcp_lp ppdev parport_pc lp parport ipv6 dm_mod dcdbas snd_hda_codec_hdmi pcspkr snd_hda_codec_realtek serio_raw i2c_i801 iTCO_wdt iTCO_vendor_support snd_hda_intel snd_hda_codec lpc_ich snd_hwdep mfd_core snd_pcm snd_page_alloc snd_timer snd soundcore acpi_cpufreq i915 video button drm_kms_helper drm mperf freq_table
> CPU: 1 PID: 16650 Comm: fbo-maxsize Not tainted 3.11.0-rc4_nightlytop_d93f59_debug_20130814_+ #6957
> Hardware name: Dell Inc. OptiPlex 9010/03JR84, BIOS A01 05/04/2012
> task: ffff8800563b3f00 ti: ffff88004bdf4000 task.ti: ffff88004bdf4000
> RIP: 0010:[<ffffffffa008fb37>] [<ffffffffa008fb37>] i915_gem_gtt_finish_object+0x73/0xc8 [i915]
> RSP: 0018:ffff88004bdf5958 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: ffff8801135e0000 RCX: ffff8800ad3bf8e0
> RDX: ffff8800ad3bf8e0 RSI: 0000000000000000 RDI: ffff8801007ee780
> RBP: ffff88004bdf5978 R08: ffff8800ad3bf8e0 R09: 0000000000000000
> R10: ffffffff86ca1810 R11: ffff880036a17101 R12: ffff8801007ee780
> R13: 0000000000018001 R14: ffff880118c4e000 R15: ffff8801007ee780
> FS: 00007f401a0ce740(0000) GS:ffff88011e280000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000008 CR3: 000000005635c000 CR4: 00000000001407e0
> Stack:
> ffff8801007ee780 ffff88005c253180 0000000000018000 ffff8801135e0000
> ffff88004bdf59a8 ffffffffa0088e55 0000000000000011 ffff8801007eec00
> 0000000000018000 ffff880036a17101 ffff88004bdf5a08 ffffffffa0089026
> Call Trace:
> [<ffffffffa0088e55>] i915_vma_unbind+0xdf/0x1ab [i915]
> [<ffffffffa0089026>] __i915_gem_shrink+0x105/0x177 [i915]
> [<ffffffffa0089452>] i915_gem_object_get_pages_gtt+0x108/0x309 [i915]
> [<ffffffffa0085ba9>] i915_gem_object_get_pages+0x61/0x90 [i915]
> [<ffffffffa008f22b>] ? gen6_ppgtt_insert_entries+0x103/0x125 [i915]
> [<ffffffffa008a113>] i915_gem_object_pin+0x1fa/0x5df [i915]
> [<ffffffffa008cdfe>] i915_gem_execbuffer_reserve_object.isra.6+0x8d/0x1bc [i915]
> [<ffffffffa008d156>] i915_gem_execbuffer_reserve+0x229/0x367 [i915]
> [<ffffffffa008dbf6>] i915_gem_do_execbuffer.isra.12+0x4dc/0xf3a [i915]
> [<ffffffff810fc823>] ? might_fault+0x40/0x90
> [<ffffffffa008eb89>] i915_gem_execbuffer2+0x187/0x222 [i915]
> [<ffffffffa000971c>] drm_ioctl+0x308/0x442 [drm]
> [<ffffffffa008ea02>] ? i915_gem_execbuffer+0x3ae/0x3ae [i915]
> [<ffffffff817db156>] ? __do_page_fault+0x3dd/0x481
> [<ffffffff8112fdba>] vfs_ioctl+0x26/0x39
> [<ffffffff811306a2>] do_vfs_ioctl+0x40e/0x451
> [<ffffffff817deda7>] ? sysret_check+0x1b/0x56
> [<ffffffff8113073c>] SyS_ioctl+0x57/0x87
> [<ffffffff8135bbfe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> [<ffffffff817ded82>] system_call_fastpath+0x16/0x1b
> Code: 48 c7 c6 84 30 0e a0 31 c0 e8 d0 e9 f7 ff bf c6 a7 00 00 e8 07 af 2c e1 41 f6 84 24 03 01 00 00 10 75 44 49 8b 84 24 08 01 00 00 <8b> 50 08 48 8b 30 49 8b 86 b0 04 00 00 48 89 c7 48 81 c7 98 00
> RIP [<ffffffffa008fb37>] i915_gem_gtt_finish_object+0x73/0xc8 [i915]
> RSP <ffff88004bdf5958>
> CR2: 0000000000000008
>
> As a consequence we need to change the "only one vma for now" check in
> vma_unbind - since vma_destroy isn't always called the obj->vma_list
> might not be empty. Instead check that the vma list is singular at the
> beginning of vma_unbind. This is also more symmetric with bind_to_vm.
>
> v2:
> - Add a paranoid WARN to mark_free in the eviction code to make sure
> we never try to evict a vma used by the execbuf code right now.
> - Move the check for a temporary execbuf vma into vma_destroy -
> otherwise the failure path cleanup in bind_to_vm will blow up.
>
> Our first attempting at fixing this was
>
> commit 1be81a2f2cfd8789a627401d470423358fba2d76
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date: Tue Aug 20 12:56:40 2013 +0100
>
> drm/i915: Don't destroy the vma placeholder during execbuffer reservation
>
> Squash with this when merging!
>
> v3: Improvements suggested in Chris' review:
> - Move the WARN_ON in vma_destroy that checks for vmas with an drm_mm
> allocation before the early return.
> - Bail out if we hit the WARN in mark_free to hopefully make the
> kernel survive for long enough to capture it.
>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Ben Widawsky <ben at bwidawsk.net>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=68298
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=68171
> Tested-by: lu hua <huax.lu at intel.com> (v2)
> Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
This fixes the igt/gem_evict_everything|alignment testcases.
-Daniel
> ---
> drivers/gpu/drm/i915/i915_gem.c | 10 ++++++----
> drivers/gpu/drm/i915/i915_gem_evict.c | 3 +++
> 2 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 17042e5..d9eee14 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2618,6 +2618,9 @@ int i915_vma_unbind(struct i915_vma *vma)
> drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
> int ret;
>
> + /* For now we only ever use 1 vma per object */
> + WARN_ON(!list_is_singular(&obj->vma_list));
> +
> if (list_empty(&vma->vma_link))
> return 0;
>
> @@ -2666,9 +2669,7 @@ destroy:
> i915_gem_vma_destroy(vma);
>
> /* Since the unbound list is global, only move to that list if
> - * no more VMAs exist.
> - * NB: Until we have real VMAs there will only ever be one */
> - WARN_ON(!list_empty(&obj->vma_list));
> + * no more VMAs exist. */
> if (list_empty(&obj->vma_list))
> list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);
>
> @@ -4171,12 +4172,13 @@ i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
> void i915_gem_vma_destroy(struct i915_vma *vma)
> {
> WARN_ON(vma->node.allocated);
> - list_del(&vma->vma_link);
>
> /* Keep the vma as a placeholder in the execbuffer reservation lists */
> if (!list_empty(&vma->exec_list))
> return;
>
> + list_del(&vma->vma_link);
> +
> kfree(vma);
> }
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
> index 91b7001..cc8974f 100644
> --- a/drivers/gpu/drm/i915/i915_gem_evict.c
> +++ b/drivers/gpu/drm/i915/i915_gem_evict.c
> @@ -37,6 +37,9 @@ mark_free(struct i915_vma *vma, struct list_head *unwind)
> if (vma->obj->pin_count)
> return false;
>
> + if (WARN_ON(!list_empty(&vma->exec_list)))
> + return false;
> +
> list_add(&vma->exec_list, unwind);
> return drm_mm_scan_add_block(&vma->node);
> }
> --
> 1.8.4.rc3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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