[kbuild-all] Re: [mlankhorst:locking-rework 61/63] drivers/gpu/drm/i915/gem/i915_gem_userptr.c:315 i915_gem_object_userptr_submit_init() error: double locked 'i915->mm.notifier_lock' (orig line 270)

tree: git://people.freedesktop.org/~mlankhorst/linux locking-rework head: a7bb9c136fffddfb2e1c5132deb1682c0d1f9fc9 commit: d2902d100d21d7af1cea25975007e7ac4e03ab4c [61/63] drm/i915: Keep userpointer bindings if seqcount is unchanged config: i386-randconfig-m021-20201013 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; Reported-by: Dan Carpenter <dan.carpenter(a)oracle.com&gt; New smatch warnings: drivers/gpu/drm/i915/gem/i915_gem_userptr.c:315 i915_gem_object_userptr_submit_init() error: double locked 'i915->mm.notifier_lock' (orig line 270) vim +315 drivers/gpu/drm/i915/gem/i915_gem_userptr.c f53270c47078c8 Maarten Lankhorst 2020-07-10 250 int i915_gem_object_userptr_submit_init(struct drm_i915_gem_object *obj) f53270c47078c8 Maarten Lankhorst 2020-07-10 251 { f53270c47078c8 Maarten Lankhorst 2020-07-10 252 struct drm_i915_private *i915 = to_i915(obj->base.dev); f53270c47078c8 Maarten Lankhorst 2020-07-10 253 const unsigned long num_pages = obj->base.size >> PAGE_SHIFT; f53270c47078c8 Maarten Lankhorst 2020-07-10 254 struct page **pvec; f53270c47078c8 Maarten Lankhorst 2020-07-10 255 unsigned int gup_flags = 0; f53270c47078c8 Maarten Lankhorst 2020-07-10 256 unsigned long notifier_seq; f53270c47078c8 Maarten Lankhorst 2020-07-10 257 int pinned, ret; f53270c47078c8 Maarten Lankhorst 2020-07-10 258 f53270c47078c8 Maarten Lankhorst 2020-07-10 259 if (obj->userptr.notifier.mm != current->mm) f53270c47078c8 Maarten Lankhorst 2020-07-10 260 return -EFAULT; f53270c47078c8 Maarten Lankhorst 2020-07-10 261 f53270c47078c8 Maarten Lankhorst 2020-07-10 262 ret = i915_gem_object_lock_interruptible(obj, NULL); f53270c47078c8 Maarten Lankhorst 2020-07-10 263 if (ret) f53270c47078c8 Maarten Lankhorst 2020-07-10 264 return ret; f53270c47078c8 Maarten Lankhorst 2020-07-10 265 d2902d100d21d7 Maarten Lankhorst 2020-10-01 266 /* optimistically try to preserve current pages while unlocked */ d2902d100d21d7 Maarten Lankhorst 2020-10-01 267 if (i915_gem_object_has_pages(obj) && d2902d100d21d7 Maarten Lankhorst 2020-10-01 268 !mmu_interval_check_retry(&obj->userptr.notifier, d2902d100d21d7 Maarten Lankhorst 2020-10-01 269 obj->userptr.notifier_seq)) { d2902d100d21d7 Maarten Lankhorst 2020-10-01 @270 ret = mutex_lock_interruptible(&i915->mm.notifier_lock); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This code looks intentional, but I don't 100% understand it so I'm just going to forward the zero day bot warning. d2902d100d21d7 Maarten Lankhorst 2020-10-01 271 if (!ret) { d2902d100d21d7 Maarten Lankhorst 2020-10-01 272 if (obj->userptr.pvec && d2902d100d21d7 Maarten Lankhorst 2020-10-01 273 !mmu_interval_read_retry(&obj->userptr.notifier, d2902d100d21d7 Maarten Lankhorst 2020-10-01 274 obj->userptr.notifier_seq)) { d2902d100d21d7 Maarten Lankhorst 2020-10-01 275 obj->userptr.page_ref++; d2902d100d21d7 Maarten Lankhorst 2020-10-01 276 mutex_unlock(&i915->mm.notifier_lock); Unlocked.