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Ulf Hansson 36050d8984 cpuidle: psci: Fix suspicious RCU usage The commit `eb1f00237a` ("lockdep,trace: Expose tracepoints"), started to expose us for tracepoints. This lead to the following RCU splat on an ARM64 Qcom board. [ 5.529634] WARNING: suspicious RCU usage [ 5.537307] sdhci-pltfm: SDHCI platform and OF driver helper [ 5.541092] 5.9.0-rc3 #86 Not tainted [ 5.541098] ----------------------------- [ 5.541105] ../include/trace/events/lock.h:37 suspicious rcu_dereference_check() usage! [ 5.541110] [ 5.541110] other info that might help us debug this: [ 5.541110] [ 5.541116] [ 5.541116] rcu_scheduler_active = 2, debug_locks = 1 [ 5.541122] RCU used illegally from extended quiescent state! [ 5.541129] no locks held by swapper/0/0. [ 5.541134] [ 5.541134] stack backtrace: [ 5.541143] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.9.0-rc3 #86 [ 5.541149] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT) [ 5.541157] Call trace: [ 5.568185] sdhci_msm 7864900.sdhci: Got CD GPIO [ 5.574186] dump_backtrace+0x0/0x1c8 [ 5.574206] show_stack+0x14/0x20 [ 5.574229] dump_stack+0xe8/0x154 [ 5.574250] lockdep_rcu_suspicious+0xd4/0xf8 [ 5.574269] lock_acquire+0x3f0/0x460 [ 5.574292] _raw_spin_lock_irqsave+0x80/0xb0 [ 5.574314] __pm_runtime_suspend+0x4c/0x188 [ 5.574341] psci_enter_domain_idle_state+0x40/0xa0 [ 5.574362] cpuidle_enter_state+0xc0/0x610 [ 5.646487] cpuidle_enter+0x38/0x50 [ 5.650651] call_cpuidle+0x18/0x40 [ 5.654467] do_idle+0x228/0x278 [ 5.657678] cpu_startup_entry+0x24/0x70 [ 5.661153] rest_init+0x1a4/0x278 [ 5.665061] arch_call_rest_init+0xc/0x14 [ 5.668272] start_kernel+0x508/0x540 Following the path in pm_runtime_put_sync_suspend() from psci_enter_domain_idle_state(), it seems like we end up using the RCU. Therefore, let's simply silence the splat by informing the RCU about it with RCU_NONIDLE. Note that, this is a temporary solution. Instead we should strive to avoid using RCU_NONIDLE (and similar), but rather push rcu_idle_enter\|exit() further down, closer to the arch specific code. However, as the CPU PM notifiers are also using the RCU, additional rework is needed. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>		History 2020-09-21 15:56:53 +02:00
arch	* A defconfig fix, from Daniel Díaz.	2020-09-20 15:06:43 -07:00
block	- Fix a regression in bdev partition locking (Christoph)	2020-09-11 11:55:28 -07:00
certs	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
crypto	Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6	2020-08-30 15:53:44 -07:00
Documentation	powerpc fixes for 5.9 #5	2020-09-18 11:48:25 -07:00
drivers	cpuidle: psci: Fix suspicious RCU usage	2020-09-21 15:56:53 +02:00
fs	fs/fs-writeback.c: adjust dirtytime_interval_handler definition to match prototype	2020-09-19 13:13:39 -07:00
include	* Fix lockdep's detection of "USED" <- "IN-NMI" inversions, from Peter	2020-09-20 15:25:33 -07:00
init	init: fix error check in clean_path()	2020-09-04 09:16:58 -07:00
ipc	ipc: adjust proc_ipc_sem_dointvec definition to match prototype	2020-09-05 12:14:29 -07:00
kernel	rcu/tree: Export rcu_idle_{enter,exit} to modules	2020-09-21 15:37:21 +02:00
lib	kcsan: kconfig: move to menu 'Generic Kernel Debugging Instruments'	2020-09-19 13:13:39 -07:00
LICENSES	LICENSES: Rename other to deprecated	2019-05-03 06:34:32 -06:00
mm	mm: fix wake_page_function() comment typos	2020-09-20 10:38:47 -07:00
net	NFS client bugfixes for Linux 5.9	2020-09-09 11:14:20 -07:00
samples	treewide: Use fallthrough pseudo-keyword	2020-08-23 17:36:59 -05:00
scripts	kconfig: qconf: revive help message in the info view	2020-09-20 12:58:54 +09:00
security	device_cgroup RCU warning fix from Amol Grover <frextrite@gmail.com>	2020-09-15 16:26:57 -07:00
sound	sound fixes for 5.9-rc6	2020-09-18 11:38:08 -07:00
tools	Fix noreturn detection for ignored sibling functions, from Josh	2020-09-20 15:31:04 -07:00
usr	Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2020-08-07 13:29:39 -07:00
virt	KVM: fix memory leak in kvm_io_bus_unregister_dev()	2020-09-11 13:15:11 -04:00
.clang-format	clang-format: Update with the latest for_each macro list	2020-09-01 12:53:42 +02:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	Opt out of scripts/get_maintainer.pl	2019-05-16 10:53:40 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	.gitignore: Add ZSTD-compressed files	2020-07-31 11:50:49 +02:00
.mailmap	mailmap: add older email addresses for Kees Cook	2020-09-19 13:13:38 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	CREDITS: Replace HTTP links with HTTPS ones	2020-07-23 14:53:58 -06:00
Kbuild	kbuild: rename hostprogs-y/always to hostprogs/always-y	2020-02-04 01:53:07 +09:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	MAINTAINERS: Fix Max's and Shravan's emails	2020-09-16 11:51:02 -07:00
Makefile	Linux 5.9-rc6	2020-09-20 16:33:55 -07:00
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.