From e9681366ea9e76ab8f75e84351f2f3ca63ee542c Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 26 Sep 2014 10:31:02 +0100 Subject: drm/i915: Do not store the error pointer for a failed userptr registration 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: [] 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:[] [] 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] [] __i915_mm_struct_free__worker+0x42/0x80 [ 73.429116] [] process_one_work+0x1ba/0x610 [ 73.429632] [] ? process_one_work+0x14f/0x610 [ 73.430153] [] worker_thread+0x6b/0x4a0 [ 73.430671] [] ? trace_hardirqs_on+0xd/0x10 [ 73.431501] [] ? process_one_work+0x610/0x610 [ 73.432030] [] kthread+0xf6/0x110 [ 73.432561] [] ? __kthread_parkme+0x80/0x80 [ 73.433100] [] ret_from_fork+0x7c/0xb0 [ 73.433644] [] ? __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 [] mmu_notifier_unregister+0x23/0x130 [ 73.437017] RSP [ 73.437704] CR2: 000000000000004c Fixes regression from commit ad46cb533d586fdb256855437af876617c6cf609 Author: Chris Wilson 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 Cc: Jacek Danecki Cc: "Gong, Zhipeng" Cc: Jacek Danecki Cc: "Ursulin, Tvrtko" Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem_userptr.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'drivers/gpu') diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index d38413997379..f5efbb836e5c 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 -- cgit v1.2.2