tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 0062442ecfef0d82cd69e3e600d5006357f8d8e4 commit: 27a5dcfe73f4b696b3de8c23a560199bb1c193a4 drm/i915/gem: Remove disordered per-file request list for throttling config: i386-randconfig-m021-20201115 (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; smatch warnings: drivers/gpu/drm/i915/gem/i915_gem_throttle.c:59 i915_gem_throttle_ioctl() error: double locked 'ctx->engines_mutex' (orig line 59) vim +59 drivers/gpu/drm/i915/gem/i915_gem_throttle.c 35 int 36 i915_gem_throttle_ioctl(struct drm_device *dev, void *data, 37 struct drm_file *file) 38 { 39 const unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES; 40 struct drm_i915_file_private *file_priv = file->driver_priv; 41 struct i915_gem_context *ctx; 42 unsigned long idx; 43 long ret; 44 45 /* ABI: return -EIO if already wedged */ 46 ret = intel_gt_terminally_wedged(&to_i915(dev)->gt); 47 if (ret) 48 return ret; 49 50 rcu_read_lock(); 51 xa_for_each(&file_priv->context_xa, idx, ctx) { 52 struct i915_gem_engines_iter it; 53 struct intel_context *ce; 54 55 if (!kref_get_unless_zero(&ctx->ref)) 56 continue; 57 rcu_read_unlock(); 58 59 for_each_gem_engine(ce, 60 i915_gem_context_lock_engines(ctx), ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I don't understand why this takes the lock every iteration through the loop 61 it) { 62 struct i915_request *rq, *target = NULL; 63 64 if (!ce->timeline) 65 continue; 66 67 mutex_lock(&ce->timeline->mutex); 68 list_for_each_entry_reverse(rq, 69 &ce->timeline->requests, 70 link) { 71 if (i915_request_completed(rq)) 72 break; 73 74 if (time_after(rq->emitted_jiffies, 75 recent_enough)) 76 continue; 77 78 target = i915_request_get(rq); 79 break; 80 } 81 mutex_unlock(&ce->timeline->mutex); 82 if (!target) 83 continue; 84 85 ret = i915_request_wait(target, 86 I915_WAIT_INTERRUPTIBLE, 87 MAX_SCHEDULE_TIMEOUT); 88 i915_request_put(target); 89 if (ret < 0) 90 break; 91 } 92 i915_gem_context_unlock_engines(ctx); But only unlocks the last element 93 i915_gem_context_put(ctx); 94 95 rcu_read_lock(); 96 } 97 rcu_read_unlock(); 98 99 return ret < 0 ? ret : 0; 100 } --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org