On Fri, Sep 26, 2014 at 10:51:54AM +0100, Tvrtko Ursulin wrote: > > On 09/26/2014 10:31 AM, Chris Wilson wrote: > >If we fail to create our mmu notification, we report the error back and > >currently store the error inside the i915_mm_struct. This not only causes > >subsequent registerations of the same mm to fail (an issue if the first > >was interrupted by a signal and needed to be restarted) but also causes > >us to eventually try and free the error pointer. > > > >[ 73.419599] BUG: unable to handle kernel NULL pointer dereference at 000000000000004c > >[ 73.419831] IP: [<ffffffff8114af33>] mmu_notifier_unregister+0x23/0x130 > >[ 73.420065] PGD 8650c067 PUD 870bb067 PMD 0 > >[ 73.420319] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC > >[ 73.420580] CPU: 0 PID: 42 Comm: kworker/0:1 Tainted: G W 3.17.0-rc6+ #1561 > >[ 73.420837] Hardware name: Intel Corporation SandyBridge Platform/LosLunas CRB, BIOS ASNBCPT1.86C.0075.P00.1106281639 06/28/2011 > >[ 73.421405] Workqueue: events __i915_mm_struct_free__worker > >[ 73.421724] task: ffff880088a81220 ti: ffff880088168000 task.ti: ffff880088168000 > >[ 73.422051] RIP: 0010:[<ffffffff8114af33>] [<ffffffff8114af33>] mmu_notifier_unregister+0x23/0x130 > >[ 73.422410] RSP: 0018:ffff88008816bd50 EFLAGS: 00010286 > >[ 73.422765] RAX: 0000000000000003 RBX: ffff880086485400 RCX: 0000000000000000 > >[ 73.423137] RDX: ffff88016d80ee90 RSI: ffff880086485400 RDI: 0000000000000044 > >[ 73.423513] RBP: ffff88008816bd70 R08: 0000000000000001 R09: 0000000000000000 > >[ 73.423895] R10: 0000000000000320 R11: 0000000000000001 R12: 0000000000000044 > >[ 73.424282] R13: ffff880166e5f008 R14: ffff88016d815200 R15: ffff880166e5f040 > >[ 73.424682] FS: 0000000000000000(0000) GS:ffff88016d800000(0000) knlGS:0000000000000000 > >[ 73.425099] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >[ 73.425537] CR2: 000000000000004c CR3: 0000000087f5f000 CR4: 00000000000407f0 > >[ 73.426157] Stack: > >[ 73.426597] ffff880088a81248 ffff880166e5f038 fffffffffffffffc ffff880166e5f008 > >[ 73.427096] ffff88008816bd98 ffffffff814a75f2 ffff880166e5f038 ffff8800880f8a28 > >[ 73.427603] ffff88016d812ac0 ffff88008816be00 ffffffff8106321a ffffffff810631af > >[ 73.428119] Call Trace: > >[ 73.428606] [<ffffffff814a75f2>] __i915_mm_struct_free__worker+0x42/0x80 > >[ 73.429116] [<ffffffff8106321a>] process_one_work+0x1ba/0x610 > >[ 73.429632] [<ffffffff810631af>] ? process_one_work+0x14f/0x610 > >[ 73.430153] [<ffffffff810636db>] worker_thread+0x6b/0x4a0 > >[ 73.430671] [<ffffffff8108d67d>] ? trace_hardirqs_on+0xd/0x10 > >[ 73.431501] [<ffffffff81063670>] ? process_one_work+0x610/0x610 > >[ 73.432030] [<ffffffff8106a206>] kthread+0xf6/0x110 > >[ 73.432561] [<ffffffff8106a110>] ? __kthread_parkme+0x80/0x80 > >[ 73.433100] [<ffffffff8169c22c>] ret_from_fork+0x7c/0xb0 > >[ 73.433644] [<ffffffff8106a110>] ? __kthread_parkme+0x80/0x80 > >[ 73.434194] Code: 0f 1f 84 00 00 00 00 00 66 66 66 66 90 8b 46 4c 85 c0 0f 8e 10 01 00 00 55 48 89 e5 41 55 41 54 53 48 89 f3 49 89 fc 48 83 ec 08 <48> 83 7f 08 00 0f 84 b1 00 00 00 48 c7 c7 40 e6 ac 82 e8 26 65 > >[ 73.435942] RIP [<ffffffff8114af33>] mmu_notifier_unregister+0x23/0x130 > >[ 73.437017] RSP <ffff88008816bd50> > >[ 73.437704] CR2: 000000000000004c > > > >Fixes regression from commit ad46cb533d586fdb256855437af876617c6cf609 > >Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >Date: Thu Aug 7 14:20:40 2014 +0100 > > > > drm/i915: Prevent recursive deadlock on releasing a busy userptr > > > >Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84207 > >Testcase: igt/gem_render_copy_redux > >Testcase: igt/gem_userptr_blits/create-destroy-sync > >Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >Cc: Jacek Danecki <jacek.danecki@xxxxxxxxx> > >Cc: "Gong, Zhipeng" <zhipeng.gong@xxxxxxxxx> > >Cc: Jacek Danecki <jacek.danecki@xxxxxxxxx> > >Cc: "Ursulin, Tvrtko" <tvrtko.ursulin@xxxxxxxxx> > >Cc: stable@xxxxxxxxxxxxxxx > >--- > > drivers/gpu/drm/i915/i915_gem_userptr.c | 24 ++++++++++++++++-------- > > 1 file changed, 16 insertions(+), 8 deletions(-) > > > >diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c > >index 903a875..ecd5c84 100644 > >--- a/drivers/gpu/drm/i915/i915_gem_userptr.c > >+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c > >@@ -293,15 +293,23 @@ i915_gem_userptr_release__mmu_notifier(struct drm_i915_gem_object *obj) > > static struct i915_mmu_notifier * > > i915_mmu_notifier_find(struct i915_mm_struct *mm) > > { > >- if (mm->mn == NULL) { > >- down_write(&mm->mm->mmap_sem); > >- mutex_lock(&to_i915(mm->dev)->mm_lock); > >- if (mm->mn == NULL) > >- mm->mn = i915_mmu_notifier_create(mm->mm); > >- mutex_unlock(&to_i915(mm->dev)->mm_lock); > >- up_write(&mm->mm->mmap_sem); > >+ struct i915_mmu_notifier *mn = mm->mn; > >+ > >+ mn = mm->mn; > >+ if (mn) > >+ return mn; > >+ > >+ down_write(&mm->mm->mmap_sem); > >+ mutex_lock(&to_i915(mm->dev)->mm_lock); > >+ if ((mn = mm->mn) == NULL) { > >+ mn = i915_mmu_notifier_create(mm->mm); > >+ if (!IS_ERR(mn)) > >+ mm->mn = mn; > > } > >- return mm->mn; > >+ mutex_unlock(&to_i915(mm->dev)->mm_lock); > >+ up_write(&mm->mm->mmap_sem); > >+ > >+ return mn; > > } > > > > static int > > > > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Queued for dinf (to give it a bit more vetting time), thanks for the patch and review. -Daniel > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html