9da397e5d4
commit 55702ec9603ebeffb15e6f7b113623fe1d8872f4 upstream.
rcutree_report_cpu_starting() must be called before
clockevents_register_device() to avoid the following lockdep splat triggered by
calling list_add() when CONFIG_PROVE_RCU_LIST=y:
WARNING: suspicious RCU usage
...
-----------------------------
kernel/locking/lockdep.c:3680 RCU-list traversed in non-reader section!!
other info that might help us debug this:
RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1
no locks held by swapper/1/0.
...
Call Trace:
[<ffffffff8012a434>] show_stack+0x64/0x158
[<ffffffff80a93d98>] dump_stack_lvl+0x90/0xc4
[<ffffffff801c9e9c>] __lock_acquire+0x1404/0x2940
[<ffffffff801cbf3c>] lock_acquire+0x14c/0x448
[<ffffffff80aa4260>] _raw_spin_lock_irqsave+0x50/0x88
[<ffffffff8021e0c8>] clockevents_register_device+0x60/0x1e8
[<ffffffff80130ff0>] r4k_clockevent_init+0x220/0x3a0
[<ffffffff801339d0>] start_secondary+0x50/0x3b8
raw_smp_processor_id() is required in order to avoid calling into lockdep
before RCU has declared the CPU to be watched for readers.
See also commit 29368e093921 ("x86/smpboot: Move rcu_cpu_starting() earlier"),
commit de5d9dae150c ("s390/smp: move rcu_cpu_starting() earlier") and commit
99f070b62322 ("powerpc/smp: Call rcu_cpu_starting() earlier").
Signed-off-by: Stefan Wiehler <stefan.wiehler@nokia.com>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.