On Tue, Mar 14, 2017 at 10:21:09PM +0900, Sergey Senozhatsky wrote:
Hello,
[ 530.698622] ====================================================== [ 530.698623] WARNING: possible circular locking dependency detected [ 530.698626] 4.11.0-rc2-mm1-dbg-00167-gdb8a9941614c-dirty #222 Not tainted [ 530.698627] ------------------------------------------------------ [ 530.698628] Xorg/343 is trying to acquire lock: [ 530.698630] (&mm->mmap_sem){++++++}, at: [<ffffffffa057e085>] i915_gem_userptr_get_pages+0x60/0x29c [i915] [ 530.698702] but task is already holding lock: [ 530.698703] (&obj->mm.lock){+.+.+.}, at: [<ffffffffa0572d78>] __i915_gem_object_get_pages+0x21/0x62 [i915] [ 530.698763] which lock already depends on the new lock.
Yup, just seen it myself. This particular cycle is a non-issue, but there is another possiblity for a mmap_sem recursion in the ggtt fault handler. -Chris