On Mon, 22 Aug 2016, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > [ 284.922349] ====================================================== > [ 284.922355] [ INFO: possible circular locking dependency detected ] > [ 284.922361] 4.8.0-rc2+ #430 Tainted: G W > [ 284.922366] ------------------------------------------------------- > [ 284.922371] cat/1197 is trying to acquire lock: > [ 284.922376] (&dev->filelist_mutex){+.+...}, at: [<ffffffffa0055ba2>] i915_ppgtt_info+0x82/0x390 [i915] > [ 284.922423] > [ 284.922423] but task is already holding lock: > [ 284.922429] (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0055b55>] i915_ppgtt_info+0x35/0x390 [i915] > [ 284.922465] > [ 284.922465] which lock already depends on the new lock. > [ 284.922465] > [ 284.922471] > [ 284.922471] the existing dependency chain (in reverse order) is: > [ 284.922477] > -> #1 (&dev->struct_mutex){+.+.+.}: > [ 284.922493] [<ffffffff81087710>] lock_acquire+0x60/0x80 > [ 284.922505] [<ffffffff8143e96f>] mutex_lock_nested+0x5f/0x360 > [ 284.922520] [<ffffffffa004f877>] print_context_stats+0x37/0xf0 [i915] > [ 284.922549] [<ffffffffa00535f5>] i915_gem_object_info+0x265/0x490 [i915] > [ 284.922581] [<ffffffff81144491>] seq_read+0xe1/0x3b0 > [ 284.922592] [<ffffffff811f77b3>] full_proxy_read+0x83/0xb0 > [ 284.922604] [<ffffffff8111ba03>] __vfs_read+0x23/0x110 > [ 284.922616] [<ffffffff8111c9b9>] vfs_read+0x89/0x110 > [ 284.922626] [<ffffffff8111dbf4>] SyS_read+0x44/0xa0 > [ 284.922636] [<ffffffff81442be9>] entry_SYSCALL_64_fastpath+0x1c/0xac > [ 284.922648] > -> #0 (&dev->filelist_mutex){+.+...}: > [ 284.922667] [<ffffffff810871fc>] __lock_acquire+0x10fc/0x1270 > [ 284.922678] [<ffffffff81087710>] lock_acquire+0x60/0x80 > [ 284.922689] [<ffffffff8143e96f>] mutex_lock_nested+0x5f/0x360 > [ 284.922701] [<ffffffffa0055ba2>] i915_ppgtt_info+0x82/0x390 [i915] > [ 284.922729] [<ffffffff81144491>] seq_read+0xe1/0x3b0 > [ 284.922739] [<ffffffff811f77b3>] full_proxy_read+0x83/0xb0 > [ 284.922750] [<ffffffff8111ba03>] __vfs_read+0x23/0x110 > [ 284.922761] [<ffffffff8111c9b9>] vfs_read+0x89/0x110 > [ 284.922771] [<ffffffff8111dbf4>] SyS_read+0x44/0xa0 > [ 284.922781] [<ffffffff81442be9>] entry_SYSCALL_64_fastpath+0x1c/0xac > [ 284.922793] > [ 284.922793] other info that might help us debug this: > [ 284.922793] > [ 284.922809] Possible unsafe locking scenario: > [ 284.922809] > [ 284.922818] CPU0 CPU1 > [ 284.922825] ---- ---- > [ 284.922831] lock(&dev->struct_mutex); > [ 284.922842] lock(&dev->filelist_mutex); > [ 284.922854] lock(&dev->struct_mutex); > [ 284.922865] lock(&dev->filelist_mutex); > [ 284.922875] > [ 284.922875] *** DEADLOCK *** > [ 284.922875] > [ 284.922888] 3 locks held by cat/1197: > [ 284.922895] #0: (debugfs_srcu){......}, at: [<ffffffff811f7730>] full_proxy_read+0x0/0xb0 > [ 284.922919] #1: (&p->lock){+.+.+.}, at: [<ffffffff811443e8>] seq_read+0x38/0x3b0 > [ 284.922942] #2: (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0055b55>] i915_ppgtt_info+0x35/0x390 [i915] > [ 284.922983] Do we have a regressing commit reference? BR, Jani. > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_debugfs.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c > index 5193b0447066..c5ef132f8b51 100644 > --- a/drivers/gpu/drm/i915/i915_debugfs.c > +++ b/drivers/gpu/drm/i915/i915_debugfs.c > @@ -2291,10 +2291,13 @@ static int i915_ppgtt_info(struct seq_file *m, void *data) > struct drm_device *dev = node->minor->dev; > struct drm_i915_private *dev_priv = to_i915(dev); > struct drm_file *file; > + int ret; > > - int ret = mutex_lock_interruptible(&dev->struct_mutex); > + mutex_lock(&dev->filelist_mutex); > + ret = mutex_lock_interruptible(&dev->struct_mutex); > if (ret) > - return ret; > + goto out_unlock; > + > intel_runtime_pm_get(dev_priv); > > if (INTEL_INFO(dev)->gen >= 8) > @@ -2302,7 +2305,6 @@ static int i915_ppgtt_info(struct seq_file *m, void *data) > else if (INTEL_INFO(dev)->gen >= 6) > gen6_ppgtt_info(m, dev); > > - mutex_lock(&dev->filelist_mutex); > list_for_each_entry_reverse(file, &dev->filelist, lhead) { > struct drm_i915_file_private *file_priv = file->driver_priv; > struct task_struct *task; > @@ -2310,19 +2312,19 @@ static int i915_ppgtt_info(struct seq_file *m, void *data) > task = get_pid_task(file->pid, PIDTYPE_PID); > if (!task) { > ret = -ESRCH; > - goto out_unlock; > + goto out_rpm; > } > seq_printf(m, "\nproc: %s\n", task->comm); > put_task_struct(task); > idr_for_each(&file_priv->context_idr, per_file_ctx, > (void *)(unsigned long)m); > } > -out_unlock: > - mutex_unlock(&dev->filelist_mutex); > > +out_rpm: > intel_runtime_pm_put(dev_priv); > mutex_unlock(&dev->struct_mutex); > - > +out_unlock: > + mutex_unlock(&dev->filelist_mutex); > return ret; > } -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx