From 4f2a572eda67aecb1e7e4fc26cc985fb8158f6e8 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sat, 28 Sep 2019 09:25:46 +0100 Subject: [PATCH] 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 Cc: Tvrtko Ursulin Cc: Daniel Vetter Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190928082546.3473-1-chris@chris-wilson.co.uk (cherry picked from commit a4311745bba9763e3c965643d4531bd5765b0513) Signed-off-by: Rodrigo Vivi --- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 7 +++++++ drivers/gpu/drm/i915/gem/i915_gem_object.h | 6 ++++++ drivers/gpu/drm/i915/gem/i915_gem_object_types.h | 3 ++- drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 1 + drivers/gpu/drm/i915/i915_gem.c | 3 +++ 5 files changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 91051e1780217d..05289edbafe34b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -364,6 +364,7 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf) return VM_FAULT_OOM; case -ENOSPC: case -EFAULT: + case -ENODEV: /* bad object, how did you get here! */ return VM_FAULT_SIGBUS; default: WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret); @@ -475,10 +476,16 @@ i915_gem_mmap_gtt(struct drm_file *file, if (!obj) return -ENOENT; + if (i915_gem_object_never_bind_ggtt(obj)) { + ret = -ENODEV; + goto out; + } + ret = create_mmap_offset(obj); if (ret == 0) *offset = drm_vma_node_offset_addr(&obj->base.vma_node); +out: i915_gem_object_put(obj); return ret; } diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h index 5efb9936e05b51..ddf3605bea8eb4 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h @@ -152,6 +152,12 @@ i915_gem_object_is_proxy(const struct drm_i915_gem_object *obj) return obj->ops->flags & I915_GEM_OBJECT_IS_PROXY; } +static inline bool +i915_gem_object_never_bind_ggtt(const struct drm_i915_gem_object *obj) +{ + return obj->ops->flags & I915_GEM_OBJECT_NO_GGTT; +} + static inline bool i915_gem_object_needs_async_cancel(const struct drm_i915_gem_object *obj) { diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h index ede0eb4218a81b..646859fea2246f 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h @@ -32,7 +32,8 @@ struct drm_i915_gem_object_ops { #define I915_GEM_OBJECT_HAS_STRUCT_PAGE BIT(0) #define I915_GEM_OBJECT_IS_SHRINKABLE BIT(1) #define I915_GEM_OBJECT_IS_PROXY BIT(2) -#define I915_GEM_OBJECT_ASYNC_CANCEL BIT(3) +#define I915_GEM_OBJECT_NO_GGTT BIT(3) +#define I915_GEM_OBJECT_ASYNC_CANCEL BIT(4) /* Interface between the GEM object and its backing storage. * get_pages() is called once prior to the use of the associated set diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c index 11b231c187c500..6b3b50f0f6d98b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c @@ -702,6 +702,7 @@ i915_gem_userptr_dmabuf_export(struct drm_i915_gem_object *obj) static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = { .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE | I915_GEM_OBJECT_IS_SHRINKABLE | + I915_GEM_OBJECT_NO_GGTT | I915_GEM_OBJECT_ASYNC_CANCEL, .get_pages = i915_gem_userptr_get_pages, .put_pages = i915_gem_userptr_put_pages, diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 95e7c52cf8edc4..d0f94f239919e1 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -969,6 +969,9 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, lockdep_assert_held(&obj->base.dev->struct_mutex); + if (i915_gem_object_never_bind_ggtt(obj)) + return ERR_PTR(-ENODEV); + if (flags & PIN_MAPPABLE && (!view || view->type == I915_GGTT_VIEW_NORMAL)) { /* If the required space is larger than the available