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@xxxxxxxxxxxxxxxxxx> > 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@xxxxxxxxxxxxxxxxxx> > Cc: Ben Widawsky <ben@xxxxxxxxxxxx> > 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@xxxxxxxxx> (v2) > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> 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 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
