Pull WW mutex support from Ingo Molnar:
"This tree adds support for wound/wait style locks, which the graphics
guys would like to make use of in the TTM graphics subsystem.
Wound/wait mutexes are used when other multiple lock acquisitions of a
similar type can be done in an arbitrary order. The deadlock handling
used here is called wait/wound in the RDBMS literature: The older
tasks waits until it can acquire the contended lock. The younger
tasks needs to back off and drop all the locks it is currently
holding, ie the younger task is wounded.
See this LWN.net description of W/W mutexes:
https://lwn.net/Articles/548909/
The comments there outline specific usecases for this facility (which
have already been implemented for the DRM tree).
Also see Documentation/ww-mutex-design.txt for more details"
* 'core-mutexes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking-selftests: Handle unexpected failures more strictly
mutex: Add more w/w tests to test EDEADLK path handling
mutex: Add more tests to lib/locking-selftest.c
mutex: Add w/w tests to lib/locking-selftest.c
mutex: Add w/w mutex slowpath debugging
mutex: Add support for wound/wait style locks
arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
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