core-rcu-2021-02-17

 - Documentation updates.

 - Miscellaneous fixes.

 - kfree_rcu() updates: Addition of mem_dump_obj() to provide allocator return
   addresses to more easily locate bugs.  This has a couple of RCU-related commits,
   but is mostly MM.  Was pulled in with akpm's agreement.

 - Per-callback-batch tracking of numbers of callbacks,
   which enables better debugging information and smarter
   reactions to large numbers of callbacks.

 - The first round of changes to allow CPUs to be runtime switched from and to
   callback-offloaded state.

 - CONFIG_PREEMPT_RT-related changes.

 - RCU CPU stall warning updates.

 - Addition of polling grace-period APIs for SRCU.

 - Torture-test and torture-test scripting updates, including a "torture everything"
   script that runs rcutorture, locktorture, scftorture, rcuscale, and refscale.
   Plus does an allmodconfig build.

 - nolibc fixes for the torture tests

Signed-off-by: Ingo Molnar <mingo@kernel.org>