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Valentin Schneider ce48c457b9 cpu/hotplug: Mute hotplug lockdep during init
Since we've had:

  commit cb538267ea ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations")

we've been getting some lockdep warnings during init, such as on HiKey960:

[    0.820495] WARNING: CPU: 4 PID: 0 at kernel/cpu.c:316 lockdep_assert_cpus_held+0x3c/0x48
[    0.820498] Modules linked in:
[    0.820509] CPU: 4 PID: 0 Comm: swapper/4 Tainted: G S                4.20.0-rc5-00051-g4cae42a #34
[    0.820511] Hardware name: HiKey960 (DT)
[    0.820516] pstate: 600001c5 (nZCv dAIF -PAN -UAO)
[    0.820520] pc : lockdep_assert_cpus_held+0x3c/0x48
[    0.820523] lr : lockdep_assert_cpus_held+0x38/0x48
[    0.820526] sp : ffff00000a9cbe50
[    0.820528] x29: ffff00000a9cbe50 x28: 0000000000000000
[    0.820533] x27: 00008000b69e5000 x26: ffff8000bff4cfe0
[    0.820537] x25: ffff000008ba69e0 x24: 0000000000000001
[    0.820541] x23: ffff000008fce000 x22: ffff000008ba70c8
[    0.820545] x21: 0000000000000001 x20: 0000000000000003
[    0.820548] x19: ffff00000a35d628 x18: ffffffffffffffff
[    0.820552] x17: 0000000000000000 x16: 0000000000000000
[    0.820556] x15: ffff00000958f848 x14: 455f3052464d4d34
[    0.820559] x13: 00000000769dde98 x12: ffff8000bf3f65a8
[    0.820564] x11: 0000000000000000 x10: ffff00000958f848
[    0.820567] x9 : ffff000009592000 x8 : ffff00000958f848
[    0.820571] x7 : ffff00000818ffa0 x6 : 0000000000000000
[    0.820574] x5 : 0000000000000000 x4 : 0000000000000001
[    0.820578] x3 : 0000000000000000 x2 : 0000000000000001
[    0.820582] x1 : 00000000ffffffff x0 : 0000000000000000
[    0.820587] Call trace:
[    0.820591]  lockdep_assert_cpus_held+0x3c/0x48
[    0.820598]  static_key_enable_cpuslocked+0x28/0xd0
[    0.820606]  arch_timer_check_ool_workaround+0xe8/0x228
[    0.820610]  arch_timer_starting_cpu+0xe4/0x2d8
[    0.820615]  cpuhp_invoke_callback+0xe8/0xd08
[    0.820619]  notify_cpu_starting+0x80/0xb8
[    0.820625]  secondary_start_kernel+0x118/0x1d0

We've also had a similar warning in sched_init_smp() for every
asymmetric system that would enable the sched_asym_cpucapacity static
key, although that was singled out in:

  commit 40fa3780ba ("sched/core: Take the hotplug lock in sched_init_smp()")

Those warnings are actually harmless, since we cannot have hotplug
operations at the time they appear. Instead of starting to sprinkle
useless hotplug lock operations in the init codepaths, mute the
warnings until they start warning about real problems.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: cai@gmx.us
Cc: daniel.lezcano@linaro.org
Cc: dietmar.eggemann@arm.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: longman@redhat.com
Cc: marc.zyngier@arm.com
Cc: mark.rutland@arm.com
Link: https://lkml.kernel.org/r/1545243796-23224-2-git-send-email-valentin.schneider@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21 11:18:53 +01:00
Documentation Devicetree fixes for v5.0: 2019-01-18 06:15:28 +12:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch openrisc: remove unneeded code in arch/openrisc/Makefile 2019-01-17 23:42:59 +09:00
block block: fix kerneldoc comment for blk_attempt_plug_merge() 2019-01-09 15:29:08 -07:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto Kconfig updates for v4.21 2018-12-29 13:03:29 -08:00
drivers First 5.0 rc pull request 2019-01-18 17:17:20 +12:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs AFS fixes 2019-01-18 06:27:24 +12:00
include sched/wake_q: Document wake_q_add() 2019-01-21 11:15:36 +01:00
init kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7 2019-01-14 10:37:09 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel cpu/hotplug: Mute hotplug lockdep during init 2019-01-21 11:18:53 +01:00
lib sbitmap: Protect swap_lock from hardirq 2019-01-15 16:29:57 +12:00
mm mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one 2019-01-10 02:58:21 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-16 05:13:36 +12:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-01-16 05:13:36 +12:00
scripts kbuild: remove unused baseprereq 2019-01-14 12:19:40 +09:00
security Merge branch 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-01-17 16:54:58 +12:00
sound remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
tools tools/memory-model: Make scripts take "-j" abbreviation for "--jobs" 2019-01-21 11:07:04 +01:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Staging driver fixes for 5.0-rc2 2019-01-14 05:49:35 +12:00
Makefile kbuild: mark prepare0 as PHONY to fix external module build 2019-01-17 23:42:59 +09:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.