mirror of https://gitee.com/openkylin/linux.git
drm/i915/userptr: Never allow userptr into the mappable GGTT
Daniel Vetter uncovered a nasty cycle in using the mmu-notifiers to
invalidate userptr objects which also happen to be pulled into GGTT
mmaps. That is when we unbind the userptr object (on mmu invalidation),
we revoke all CPU mmaps, which may then recurse into mmu invalidation.
We looked for ways of breaking the cycle, but the revocation on
invalidation is required and cannot be avoided. The only solution we
could see was to not allow such GGTT bindings of userptr objects in the
first place. In practice, no one really wants to use a GGTT mmapping of
a CPU pointer...
Just before Daniel's explosive lockdep patches land in v5.4-rc1, we got
a genuine blip from CI:
<4>[ 246.793958] ======================================================
<4>[ 246.793972] WARNING: possible circular locking dependency detected
<4>[ 246.793989] 5.3.0-gbd6c56f50d15-drmtip_372+ #1 Tainted: G U
<4>[ 246.794003] ------------------------------------------------------
<4>[ 246.794017] kswapd0/145 is trying to acquire lock:
<4>[ 246.794030] 000000003f565be6 (&dev->struct_mutex/1){+.+.}, at: userptr_mn_invalidate_range_start+0x18f/0x220 [i915]
<4>[ 246.794250]
but task is already holding lock:
<4>[ 246.794263] 000000001799cef9 (&anon_vma->rwsem){++++}, at: page_lock_anon_vma_read+0xe6/0x2a0
<4>[ 246.794291]
which lock already depends on the new lock.
<4>[ 246.794307]
the existing dependency chain (in reverse order) is:
<4>[ 246.794322]
-> #3 (&anon_vma->rwsem){++++}:
<4>[ 246.794344] down_write+0x33/0x70
<4>[ 246.794357] __vma_adjust+0x3d9/0x7b0
<4>[ 246.794370] __split_vma+0x16a/0x180
<4>[ 246.794385] mprotect_fixup+0x2a5/0x320
<4>[ 246.794399] do_mprotect_pkey+0x208/0x2e0
<4>[ 246.794413] __x64_sys_mprotect+0x16/0x20
<4>[ 246.794429] do_syscall_64+0x55/0x1c0
<4>[ 246.794443] entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4>[ 246.794456]
-> #2 (&mapping->i_mmap_rwsem){++++}:
<4>[ 246.794478] down_write+0x33/0x70
<4>[ 246.794493] unmap_mapping_pages+0x48/0x130
<4>[ 246.794519] i915_vma_revoke_mmap+0x81/0x1b0 [i915]
<4>[ 246.794519] i915_vma_unbind+0x11d/0x4a0 [i915]
<4>[ 246.794519] i915_vma_destroy+0x31/0x300 [i915]
<4>[ 246.794519] __i915_gem_free_objects+0xb8/0x4b0 [i915]
<4>[ 246.794519] drm_file_free.part.0+0x1e6/0x290
<4>[ 246.794519] drm_release+0xa6/0xe0
<4>[ 246.794519] __fput+0xc2/0x250
<4>[ 246.794519] task_work_run+0x82/0xb0
<4>[ 246.794519] do_exit+0x35b/0xdb0
<4>[ 246.794519] do_group_exit+0x34/0xb0
<4>[ 246.794519] __x64_sys_exit_group+0xf/0x10
<4>[ 246.794519] do_syscall_64+0x55/0x1c0
<4>[ 246.794519] entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4>[ 246.794519]
-> #1 (&vm->mutex){+.+.}:
<4>[ 246.794519] i915_gem_shrinker_taints_mutex+0x6d/0xe0 [i915]
<4>[ 246.794519] i915_address_space_init+0x9f/0x160 [i915]
<4>[ 246.794519] i915_ggtt_init_hw+0x55/0x170 [i915]
<4>[ 246.794519] i915_driver_probe+0xc9f/0x1620 [i915]
<4>[ 246.794519] i915_pci_probe+0x43/0x1b0 [i915]
<4>[ 246.794519] pci_device_probe+0x9e/0x120
<4>[ 246.794519] really_probe+0xea/0x3d0
<4>[ 246.794519] driver_probe_device+0x10b/0x120
<4>[ 246.794519] device_driver_attach+0x4a/0x50
<4>[ 246.794519] __driver_attach+0x97/0x130
<4>[ 246.794519] bus_for_each_dev+0x74/0xc0
<4>[ 246.794519] bus_add_driver+0x13f/0x210
<4>[ 246.794519] driver_register+0x56/0xe0
<4>[ 246.794519] do_one_initcall+0x58/0x300
<4>[ 246.794519] do_init_module+0x56/0x1f6
<4>[ 246.794519] load_module+0x25bd/0x2a40
<4>[ 246.794519] __se_sys_finit_module+0xd3/0xf0
<4>[ 246.794519] do_syscall_64+0x55/0x1c0
<4>[ 246.794519] entry_SYSCALL_64_after_hwframe+0x49/0xbe
<4>[ 246.794519]
-> #0 (&dev->struct_mutex/1){+.+.}:
<4>[ 246.794519] __lock_acquire+0x15d8/0x1e90
<4>[ 246.794519] lock_acquire+0xa6/0x1c0
<4>[ 246.794519] __mutex_lock+0x9d/0x9b0
<4>[ 246.794519] userptr_mn_invalidate_range_start+0x18f/0x220 [i915]
<4>[ 246.794519] __mmu_notifier_invalidate_range_start+0x85/0x110
<4>[ 246.794519] try_to_unmap_one+0x76b/0x860
<4>[ 246.794519] rmap_walk_anon+0x104/0x280
<4>[ 246.794519] try_to_unmap+0xc0/0xf0
<4>[ 246.794519] shrink_page_list+0x561/0xc10
<4>[ 246.794519] shrink_inactive_list+0x220/0x440
<4>[ 246.794519] shrink_node_memcg+0x36e/0x740
<4>[ 246.794519] shrink_node+0xcb/0x490
<4>[ 246.794519] balance_pgdat+0x241/0x580
<4>[ 246.794519] kswapd+0x16c/0x530
<4>[ 246.794519] kthread+0x119/0x130
<4>[ 246.794519] ret_from_fork+0x24/0x50
<4>[ 246.794519]
other info that might help us debug this:
<4>[ 246.794519] Chain exists of:
&dev->struct_mutex/1 --> &mapping->i_mmap_rwsem --> &anon_vma->rwsem
<4>[ 246.794519] Possible unsafe locking scenario:
<4>[ 246.794519] CPU0 CPU1
<4>[ 246.794519] ---- ----
<4>[ 246.794519] lock(&anon_vma->rwsem);
<4>[ 246.794519] lock(&mapping->i_mmap_rwsem);
<4>[ 246.794519] lock(&anon_vma->rwsem);
<4>[ 246.794519] lock(&dev->struct_mutex/1);
<4>[ 246.794519]
*** DEADLOCK ***
v2: Say no to mmap_ioctl
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111744
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111870
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190928082546.3473-1-chris@chris-wilson.co.uk
(cherry picked from commit a4311745bb)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson
Rodrigo Vivi
parent
0336ab5808
commit
4f2a572eda
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@ -364,6 +364,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
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return VM_FAULT_OOM;
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case -ENOSPC:
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case -EFAULT:
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case -ENODEV: /* bad object, how did you get here! */
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return VM_FAULT_SIGBUS;
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default:
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WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret);
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@ -475,10 +476,16 @@ i915_gem_mmap_gtt(struct drm_file *file,
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if (!obj)
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return -ENOENT;
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if (i915_gem_object_never_bind_ggtt(obj)) {
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ret = -ENODEV;
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goto out;
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}
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ret = create_mmap_offset(obj);
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if (ret == 0)
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*offset = drm_vma_node_offset_addr(&obj->base.vma_node);
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out:
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i915_gem_object_put(obj);
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return ret;
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}
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@ -152,6 +152,12 @@ i915_gem_object_is_proxy(const struct drm_i915_gem_object *obj)
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return obj->ops->flags & I915_GEM_OBJECT_IS_PROXY;
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}
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static inline bool
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i915_gem_object_never_bind_ggtt(const struct drm_i915_gem_object *obj)
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{
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return obj->ops->flags & I915_GEM_OBJECT_NO_GGTT;
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}
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static inline bool
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i915_gem_object_needs_async_cancel(const struct drm_i915_gem_object *obj)
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{
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@ -32,7 +32,8 @@ struct drm_i915_gem_object_ops {
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#define I915_GEM_OBJECT_HAS_STRUCT_PAGE BIT(0)
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#define I915_GEM_OBJECT_IS_SHRINKABLE BIT(1)
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#define I915_GEM_OBJECT_IS_PROXY BIT(2)
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#define I915_GEM_OBJECT_ASYNC_CANCEL BIT(3)
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#define I915_GEM_OBJECT_NO_GGTT BIT(3)
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#define I915_GEM_OBJECT_ASYNC_CANCEL BIT(4)
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/* Interface between the GEM object and its backing storage.
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* get_pages() is called once prior to the use of the associated set
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@ -702,6 +702,7 @@ i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj)
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static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = {
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.flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE |
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I915_GEM_OBJECT_IS_SHRINKABLE |
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I915_GEM_OBJECT_NO_GGTT |
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I915_GEM_OBJECT_ASYNC_CANCEL,
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.get_pages = i915_gem_userptr_get_pages,
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.put_pages = i915_gem_userptr_put_pages,
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@ -969,6 +969,9 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
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lockdep_assert_held(&obj->base.dev->struct_mutex);
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if (i915_gem_object_never_bind_ggtt(obj))
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return ERR_PTR(-ENODEV);
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if (flags & PIN_MAPPABLE &&
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(!view || view->type == I915_GGTT_VIEW_NORMAL)) {
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/* If the required space is larger than the available
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