From 28647b52ec0e20f84eb1b5e13095134e2b371759 Mon Sep 17 00:00:00 2001 From: Michal Wajdeczko Date: Wed, 31 Jan 2018 17:32:39 +0000 Subject: [PATCH] drm/i915/guc: Don't try to create log runtime if there is no log In case of GuC initialization failure we may continue with driver load, but we wrongly assume that GuC is fully functional. This leads to the BUG as we attempt to access non-existing log vma. [26386.121085] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0 [26386.121225] IP: guc_log_runtime_create+0x23/0xe0 [i915] [26386.121763] Call Trace: [26386.121870] guc_log_late_setup+0xfd/0x140 [i915] [26386.121969] i915_driver_load+0x7ab/0x1730 [i915] [26386.122069] i915_pci_probe+0x2d/0x90 [i915] [26386.122089] pci_device_probe+0x9c/0x120 [26386.122107] driver_probe_device+0x2a9/0x490 [26386.122126] __driver_attach+0xd9/0xe0 [26386.122143] ? driver_probe_device+0x490/0x490 [26386.122158] bus_for_each_dev+0x57/0x90 [26386.122175] bus_add_driver+0x1eb/0x260 [26386.122190] ? 0xffffffffa069a000 [26386.122206] driver_register+0x52/0xc0 [26386.122220] ? 0xffffffffa069a000 [26386.122234] do_one_initcall+0x39/0x170 [26386.122252] ? kmem_cache_alloc_trace+0x1fd/0x2e0 [26386.122273] do_init_module+0x56/0x1ec [26386.122289] load_module+0x219e/0x2550 [26386.122309] ? vfs_read+0x121/0x140 [26386.122331] ? SyS_finit_module+0xa5/0xe0 [26386.122346] SyS_finit_module+0xa5/0xe0 [26386.122371] entry_SYSCALL_64_fastpath+0x22/0x8f Signed-off-by: Michal Wajdeczko Cc: Chris Wilson Cc: Michal Winiarski Cc: Daniele Ceraolo Spurio Cc: Sagar Arun Kamble Link: https://patchwork.freedesktop.org/patch/msgid/20180131173241.19704-4-michal.wajdeczko@intel.com Reviewed-by: Sagar Arun Kamble Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/intel_guc_log.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c index 3fbe93ac81dc..7b5074e2120c 100644 --- a/drivers/gpu/drm/i915/intel_guc_log.c +++ b/drivers/gpu/drm/i915/intel_guc_log.c @@ -397,6 +397,9 @@ static int guc_log_runtime_create(struct intel_guc *guc) lockdep_assert_held(&dev_priv->drm.struct_mutex); + if (!guc->log.vma) + return -ENODEV; + GEM_BUG_ON(guc_log_has_runtime(guc)); ret = i915_gem_object_set_to_wc_domain(guc->log.vma->obj, true); -- 2.30.2