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Patrick Wang 69732d2151 rcu: Avoid tracing a few functions executed in stop machine 
commit 48f8070f5d upstream.

Stop-machine recently started calling additional functions while waiting:

----------------------------------------------------------------
Former stop machine wait loop:
do {
    cpu_relax(); => macro
    ...
} while (curstate != STOPMACHINE_EXIT);
-----------------------------------------------------------------
Current stop machine wait loop:
do {
    stop_machine_yield(cpumask); => function (notraced)
    ...
    touch_nmi_watchdog(); => function (notraced, inside calls also notraced)
    ...
    rcu_momentary_dyntick_idle(); => function (notraced, inside calls traced)
} while (curstate != MULTI_STOP_EXIT);
------------------------------------------------------------------

These functions (and the functions that they call) must be marked
notrace to prevent them from being updated while they are executing.
The consequences of failing to mark these functions can be severe:

  rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
  rcu: 	1-...!: (0 ticks this GP) idle=14f/1/0x4000000000000000 softirq=3397/3397 fqs=0
  rcu: 	3-...!: (0 ticks this GP) idle=ee9/1/0x4000000000000000 softirq=5168/5168 fqs=0
  	(detected by 0, t=8137 jiffies, g=5889, q=2 ncpus=4)
  Task dump for CPU 1:
  task:migration/1     state:R  running task     stack:    0 pid:   19 ppid:     2 flags:0x00000000
  Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
  Call Trace:
  Task dump for CPU 3:
  task:migration/3     state:R  running task     stack:    0 pid:   29 ppid:     2 flags:0x00000000
  Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
  Call Trace:
  rcu: rcu_preempt kthread timer wakeup didn't happen for 8136 jiffies! g5889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
  rcu: 	Possible timer handling issue on cpu=2 timer-softirq=594
  rcu: rcu_preempt kthread starved for 8137 jiffies! g5889 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=2
  rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
  rcu: RCU grace-period kthread stack dump:
  task:rcu_preempt     state:I stack:    0 pid:   14 ppid:     2 flags:0x00000000
  Call Trace:
    schedule+0x56/0xc2
    schedule_timeout+0x82/0x184
    rcu_gp_fqs_loop+0x19a/0x318
    rcu_gp_kthread+0x11a/0x140
    kthread+0xee/0x118
    ret_from_exception+0x0/0x14
  rcu: Stack dump where RCU GP kthread last ran:
  Task dump for CPU 2:
  task:migration/2     state:R  running task     stack:    0 pid:   24 ppid:     2 flags:0x00000000
  Stopper: multi_cpu_stop+0x0/0x18c <- stop_machine_cpuslocked+0x128/0x174
  Call Trace:

This commit therefore marks these functions notrace:
 rcu_preempt_deferred_qs()
 rcu_preempt_need_deferred_qs()
 rcu_preempt_deferred_qs_irqrestore()

[ paulmck: Apply feedback from Neeraj Upadhyay. ]

Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Ronald Monthero <debug.penguin32@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-12-08 08:48:02 +01:00
arch parisc: Drop the HP-UX ENOSYM and EREMOTERELEASE error codes 2023-12-08 08:48:02 +01:00
block blk-core: use pr_warn_ratelimited() in bio_check_ro() 2023-11-20 11:08:29 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 16:56:18 +00:00
Documentation Documentation: sysctl: align cells in second content column 2023-10-25 11:58:54 +02:00
drivers Input: xpad - add HyperX Clutch Gladiate Support 2023-12-08 08:48:02 +01:00
fs btrfs: make error messages more clear when getting a chunk map 2023-12-08 08:48:02 +01:00
include proc: sysctl: prevent aliased sysctls from getting passed to init 2023-12-03 07:31:24 +01:00
init proc: sysctl: prevent aliased sysctls from getting passed to init 2023-12-03 07:31:24 +01:00
io_uring io_uring: fix off-by one bvec index 2023-12-03 07:31:26 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel rcu: Avoid tracing a few functions executed in stop machine 2023-12-08 08:48:02 +01:00
lib parisc: Drop the HP-UX ENOSYM and EREMOTERELEASE error codes 2023-12-08 08:48:02 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: kmem: drop __GFP_NOFAIL when allocating objcg vectors 2023-11-28 16:56:35 +00:00
net vlan: move dev_put into vlan_dev_uninit 2023-12-08 08:48:02 +01:00
samples samples/hw_breakpoint: fix building without module unloading 2023-09-23 11:10:01 +02:00
scripts randstruct: Fix gcc-plugin performance mode to stay in group 2023-11-28 16:56:26 +00:00
security KEYS: trusted: Rollback init_trusted() consistently 2023-11-28 16:56:30 +00:00
sound ALSA: hda/realtek: Add supported ALC257 for ChromeOS 2023-12-08 08:48:01 +01:00
tools parisc: Drop the HP-UX ENOSYM and EREMOTERELEASE error codes 2023-12-08 08:48:02 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:22:40 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 iio: stx104: Move to addac subdirectory 2023-08-26 14:23:27 +02:00
Makefile Linux 5.15.141 2023-12-03 07:31:26 +01:00
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.