Merge tag 'core-rcu-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Thomas Gleixner:
"RCU, LKMM and KCSAN updates collected by Paul McKenney.

RCU:
-

Merge tag 'core-rcu-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Thomas Gleixner:
"RCU, LKMM and KCSAN updates collected by Paul McKenney.

RCU:
- Avoid cpuinfo-induced IPI pileups and idle-CPU IPIs

- Lockdep-RCU updates reducing the need for __maybe_unused

- Tasks-RCU updates

- Miscellaneous fixes

- Documentation updates

- Torture-test updates

KCSAN:
- updates for selftests, avoiding setting watchpoints on NULL pointers

- fix to watchpoint encoding

LKMM:
- updates for documentation along with some updates to example-code
litmus tests"

* tag 'core-rcu-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
srcu: Take early exit on memory-allocation failure
rcu/tree: Defer kvfree_rcu() allocation to a clean context
rcu: Do not report strict GPs for outgoing CPUs
rcu: Fix a typo in rcu_blocking_is_gp() header comment
rcu: Prevent lockdep-RCU splats on lock acquisition/release
rcu/tree: nocb: Avoid raising softirq for offloaded ready-to-execute CBs
rcu,ftrace: Fix ftrace recursion
rcu/tree: Make struct kernel_param_ops definitions const
rcu/tree: Add a warning if CPU being onlined did not report QS already
rcu: Clarify nocb kthreads naming in RCU_NOCB_CPU config
rcu: Fix single-CPU check in rcu_blocking_is_gp()
rcu: Implement rcu_segcblist_is_offloaded() config dependent
list.h: Update comment to explicitly note circular lists
rcu: Panic after fixed number of stalls
x86/smpboot: Move rcu_cpu_starting() earlier
rcu: Allow rcu_irq_enter_check_tick() from NMI
tools/memory-model: Label MP tests' producers and consumers
tools/memory-model: Use "buf" and "flag" for message-passing tests
tools/memory-model: Add types to litmus tests
tools/memory-model: Add a glossary of LKMM terms
...

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Merge branch 'lkmm.2020.11.06a' into HEAD

lkmm.2020.11.06a: Linux-kernel memory model (LKMM) updates.

tools/memory-model: Label MP tests' producers and consumers

This commit adds comments that label the MP tests' producer and consumer
processes, and also that label the "exists" clause as the bad out

tools/memory-model: Label MP tests' producers and consumers

This commit adds comments that label the MP tests' producer and consumer
processes, and also that label the "exists" clause as the bad outcome.

Reported-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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tools/memory-model: Add types to litmus tests

This commit adds type information for global variables in the litmus
tests in order to allow easier use with klitmus7.

Signed-off-by: Paul E. McKenney

tools/memory-model: Add types to litmus tests

This commit adds type information for global variables in the litmus
tests in order to allow easier use with klitmus7.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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Merge tag 'v4.20' into for-linus

Sync with mainline to get linux/overflow.h among other things.

Merge tag 'v4.20' into next

Merge with mainline to bring in the new APIs.

Merge drm/drm-next into drm-intel-next-queued

We need a backmerge to get DP_DPCD_REV_14 before we push other
i915 changes to dinq that could break compilation.

Signed-off-by: Rodrigo Vivi <rodrigo.

Merge drm/drm-next into drm-intel-next-queued

We need a backmerge to get DP_DPCD_REV_14 before we push other
i915 changes to dinq that could break compilation.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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Merge tag 'v4.18-rc2' of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux into fbdev-for-next

Linux 4.18-rc2

Merge tag 'v4.18-rc2' into next-general

Merge to Linux 4.18-rc2 for security subsystem developers.

Merge branch 'linus' into x86/urgent

Required to queue a dependent fix.

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

- Lots of tidying up changes all across the map for Linux's fo

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:

- Lots of tidying up changes all across the map for Linux's formal
memory/locking-model tooling, by Alan Stern, Akira Yokosawa, Andrea
Parri, Paul E. McKenney and SeongJae Park.

Notable changes beyond an overall update in the tooling itself is the
tidying up of spin_is_locked() semantics, which spills over into the
kernel proper as well.

- qspinlock improvements: the locking algorithm now guarantees forward
progress whereas the previous implementation in mainline could starve
threads indefinitely in cmpxchg() loops. Also other related cleanups
to the qspinlock code (Will Deacon)

- misc smaller improvements, cleanups and fixes all across the locking
subsystem

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
locking/rwsem: Simplify the is-owner-spinnable checks
tools/memory-model: Add reference for 'Simplifying ARM concurrency'
tools/memory-model: Update ASPLOS information
MAINTAINERS, tools/memory-model: Update e-mail address for Andrea Parri
tools/memory-model: Fix coding style in 'lock.cat'
tools/memory-model: Remove out-of-date comments and code from lock.cat
tools/memory-model: Improve mixed-access checking in lock.cat
tools/memory-model: Improve comments in lock.cat
tools/memory-model: Remove duplicated code from lock.cat
tools/memory-model: Flag "cumulativity" and "propagation" tests
tools/memory-model: Add model support for spin_is_locked()
tools/memory-model: Add scripts to test memory model
tools/memory-model: Fix coding style in 'linux-kernel.def'
tools/memory-model: Model 'smp_store_mb()'
tools/memory-order: Update the cheat-sheet to show that smp_mb__after_atomic() orders later RMW operations
tools/memory-order: Improve key for SELF and SV
tools/memory-model: Fix cheat sheet typo
tools/memory-model: Update required version of herdtools7
tools/memory-model: Redefine rb in terms of rcu-fence
tools/memory-model: Rename link and rcu-path to rcu-link and rb
...

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tools/memory-model: Add model support for spin_is_locked()

This commit first adds a trivial macro for spin_is_locked() to
linux-kernel.def.

It also adds cat code for enumerating all possible matche

tools/memory-model: Add model support for spin_is_locked()

This commit first adds a trivial macro for spin_is_locked() to
linux-kernel.def.

It also adds cat code for enumerating all possible matches of lock
write events (set LKW) with islocked events returning true (set RL,
for Read from Lock), and unlock write events (set UL) with islocked
events returning false (set RU, for Read from Unlock). Note that this
intentionally does not model uniprocessor kernels (CONFIG_SMP=n) built
with CONFIG_DEBUG_SPINLOCK=n, in which spin_is_locked() unconditionally
returns zero.

It also adds a pair of litmus tests demonstrating the minimal ordering
provided by spin_is_locked() in conjunction with spin_lock(). Will Deacon
noted that this minimal ordering happens on ARMv8:
https://lkml.kernel.org/r/20180226162426.GB17158@arm.com

Notice that herd7 installations strictly older than version 7.49
do not handle the new constructs.

Signed-off-by: Luc Maranget <luc.maranget@inria.fr>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Maranget <Luc.Maranget@inria.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1526340837-12222-10-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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