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It looks that GuC log functionality is not fully functional yet and
causes issues when enabled by auto(-1) modparam on debug builds.
For example, but not limited to:
[ 30.062893] ======================================================
[ 30.062894] WARNING: possible circular locking dependency detected
[ 30.062895] 4.15.0-rc8-CI-CI_DRM_3648+ #1 Tainted: G U
[ 30.062896] ------------------------------------------------------
[ 30.062897] debugfs_test/1268 is trying to acquire lock:
[ 30.062898] (&dev->struct_mutex){+.+.}, at: [<00000000e4213449>] i915_mutex_lock_interruptible+0x47/0x130 [i915]
[ 30.062921]
but task is already holding lock:
[ 30.062921] (&mm->mmap_sem){++++}, at: [<00000000dd7adc93>] __do_page_fault+0x106/0x560
[ 30.062924]
which lock already depends on the new lock.
References: 0ed8795353 ("drm/i915/guc: Redefine guc_log_level modparam values")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104693
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104694
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104695
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Saarinen <jani.saarinen@intel.com>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Cc: Marta Lofstedt <marta.lofstedt@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180119124926.29844-1-michal.wajdeczko@intel.com
Reviewed-by: Michal Winiarski <michal.winiarski@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.